Patent Application
20150344888
1. Field
Inhibitors of USP30 and methods of using inhibitors of USP30 are provided. In some embodiments, methods of treating conditions involving mitochondrial defects are provided.
2. Background
Mitophagy is a specialized autophagy pathway that eliminates mitochondria through degradation by lysosomes. As such, it removes mitochondria during normal cellular turnover of organelles, during maturation of erythrocytes, and following fertilization to eliminate sperm-derived mitochondria. Mitophagy also mediates the clearance of damaged mitochondria, an important aspect of mitochondria quality control. Defective or excess mitochondria, if left uncleared, may become an aberrant source of oxidative stress and compromise healthy mitochondria through mitochondrial fusion. In yeast, selective blockade of mitophagy causes increased production of reactive oxygen species (ROS) by excess mitochondria and loss of mitochondrial DNA (mt-DNA). Impaired mitochondria quality control could also affect key biosynthetic pathways, ATP production, and Ca2+ buffering, and disturb overall cellular homeostasis.
Parkinson's disease (PD), the second most common neurodegenerative disorder after Alzheimer's disease (AD), is characterized most prominently by loss of dopaminergic neurons in the substantia nigra. Although the pathogenic mechanisms of PD are not clear, several lines of evidence suggest that mitochondrial dysfunction is central to PD. MPTP, a mitochondrial toxin, damages dopamine neurons and produces clinical parkinsonism in humans. Epidemiologic evidence links PD with exposure to pesticides such as rotenone (a complex I inhibitor) and paraquat (an oxidative stressor). Consistent with mitochondrial impairment, reduced complex I activity and high levels of mt-DNA mutations have been found in substantia nigra from PD patients. Similarly, functional and morphological changes in mitochondria are present in genetic models of PD. Perhaps most compellingly, early-onset familial PD can be caused by mutations in Parkin ubiquitin-ligase and PINK1 serine/threonine protein kinase, both of which function to maintain healthy mitochondria through regulating mitochondrial dynamics and quality control.
Genetic studies in flies established that PINK1 acts upstream of Parkin to maintain proper mitochondria morphology and function. PINK1 recruits Parkin from the cytoplasm to the surface of damaged mitochondria, leading to Parkin-mediated ubiquitination of mitochondrial outer membrane proteins and removal of damaged mitochondria by mitophagy. PD-associated mutations in either PINK1 or Parkin impair Parkin recruitment, mitochondrial ubiquitination and mitophagy. Parkin regulates multiple aspects of mitochondrial function such as mitochondrial dynamics and trafficking, and may also influence mitochondria biogenesis. The degradation of a broad range of outer mitochondrial membrane proteins on damaged mitochondria appears to be affected by Parkin. Among these mitochondria associated proteins, MIRO, a component of the mitochondria-kinesin motor adaptor complex, may be a shared substrate of both Parkin and PINK-1.
Parkin expression and/or activity can be impaired through genetic mutations in familial PD or by phosphorylation in sporadic PD. In the context of the inherently high mitochondrial oxidative stress in substantia nigra dopamine neurons, loss of Parkin-mediated mitochondrial quality control could explain the greater susceptibility of substantia nigra neurons to neurodegeneration. Promoting clearance of damaged mitochondria and enhancing mitochondrial quality control could be beneficial in PD.
In some embodiments, methods of increasing mitophagy in a cell are provided. In some embodiments, the method comprises contacting the cell with an inhibitor of USP30.
In some embodiments, methods of increasing mitochondrial ubiquitination in a cell are provided. In some embodiments, methods of increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, at least ten, at least eleven, at least twelve, at least thirteen, or fourteen proteins selected from Tom20, MIRO, MUL1, ASNS, FKBP8, TOM70, MAT2B, PRDX3, IDE, VDAC1, VDAC2, VDAC3, IP05, PSD13, UBP13, and PTH2 in a cell are provided. In some embodiments, the method comprises contacting the cell with an inhibitor of USP30.
In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, or three amino acids selected from K56, K61, and K68 of Tom 20. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, or eight amino acids selected from K153, K187, K330, K427, K512, K535, K567, and K572 of MIRO. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, or three amino acids selected from K273, K299, and K52 of MUL1. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, or nine amino acids selected from K147, K168, K176, K221, K244, K275, K478, K504, and K556 of ASNS. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, or eight amino acids selected from K249, K271, K273, K284, K307, K317, K334, and K340 of FKBP8. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten amino acids selected from K78, K120, K123, K126, K129, K148, K168, K170, K178, K185, K204, K230, K233, K245, K275, K278, K312, K326, K349, K359, K441, K463, K470, K471, K494, K501, K524, K536, K563, K570, K599, K600, and K604 of TOM70. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, or four amino acids selected from K209, K245, K316, and K326 of MAT2B. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, or five amino acids selected from K83, K91, K166, K241, and K253 of PRDX3. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, or six amino acids selected from K558, K657, K854, K884, K929, and K933 of IDE. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, or seven amino acids selected from K20, K53, K61, K109, K110, K266, and K274 of VDAC1. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, or six amino acids selected from K31, K64, K120, K121, K277, and K285 of VDAC2. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, or eight amino acids selected from K20, K53, K61, K109, K110, K163, K266, and K274 of VDAC3. In some embodiments, the method comprises increasing ubiquitination of at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten amino acids selected from K238, K353, K436, K437, K548, K556, K613, K678, K690, K705, K775, and K806 of IP05. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten amino acids selected from K2, K32, K99, K115, K122, K132, K161, K186, K313, K321, K347, K350, and K361 of PSD13. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten amino acids selected from K18, K190, K259, K326, K328, K401, K405, K414, K418, K435, K586, K587, and K640 of UBP13. In some embodiments, the method comprises increasing ubiquitination of at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, or nine amino acids selected from 47, 76, 81, 95, 106, 119, 134, 171, 177 of PTH2.
In some embodiments, the cell is under oxidative stress. In some embodiments, methods of reducing oxidative stress in a cell are provided. In some embodiments, a method comprises contacting the cell with an inhibitor of USP30.
In some embodiments, the cell comprises a pathogenic mutation in Parkin, a pathogenic mutation in PINK1, or a pathogenic mutation in Parkin and a pathogenic mutation in PINK1. Nonlimiting exemplary pathogenic mutations in Parkin are shown in Table 1. Thus, in some embodiments, the pathogenic mutation in Parkin is selected from the mutations in Table 1. Nonlimiting exemplary pathogenic mutations in PINK1 are shown in Table 2. In some embodiments, the pathogenic mutation in PINK1 selected from the mutations in Table 2.
In various embodiments, the cell is selected from a neuron, a cardiac cell, and a muscle cell. In some such embodiments, the cell is ex vivo or in vitro. Alternatively, in some such embodiments, the cell is comprised in a subject.
In some embodiments, methods of treating conditions involving mitochondrial defects in a subject are provided. In some embodiments, the method comprises administering to the subject an effective amount of an inhibitor of USP30. In some embodiments, the condition involving a mitochondrial defect is selected from a condition involving a mitophagy defect, a condition involving a mutation in mitochondrial DNA, a condition involving mitochondrial oxidative stress, a condition involving a defect in mitochondrial shape or morphology, a condition involving a defect in mitochondrial membrane potential, and a condition involving a lysosomal storage defect.
In some embodiments, the condition involving a mitochondrial defect is selected from a neurodegenerative disease; mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome; Leber's hereditary optic neuropathy (LHON); neuropathy, ataxia, retinitis pigmentosa-maternally inherited Leigh syndrome (NARP-MILS); Danon disease; ischemic heart disease leading to myocardial infarction; multiple sulfatase deficiency (MSD); mucolipidosis II (ML II); mucolipidosis III (ML III); mucolipidosis IV (ML IV); GM1-gangliosidosis (GM1); neuronal ceroid-lipofuscinoses (NCL1); Alpers disease; Barth syndrome; Beta-oxidation defects; carnitine-acyl-carnitine deficiency; carnitine deficiency; creatine deficiency syndromes; co-enzyme Q10 deficiency; complex I deficiency; complex II deficiency; complex III deficiency; complex IV deficiency; complex V deficiency; COX deficiency; chronic progressive external ophthalmoplegia syndrome (CPEO); CPT I deficiency; CPT II deficiency; glutaric aciduria type II; Kearns-Sayre syndrome; lactic acidosis; long-chain acyl-CoA dehydrongenase deficiency (LCHAD); Leigh disease or syndrome; lethal infantile cardiomyopathy (LIC); Luft disease; glutaric aciduria type II; medium-chain acyl-CoA dehydrongenase deficiency (MCAD); myoclonic epilepsy and ragged-red fiber (MERRF) syndrome; mitochondrial recessive ataxia syndrome; mitochondrial cytopathy; mitochondrial DNA depletion syndrome; myoneurogastointestinal disorder and encephalopathy; Pearson syndrome; pyruvate carboxylase deficiency; pyruvate dehydrogenase deficiency; POLG mutations; medium/short-chain 3-hydroxyacyl-CoA dehydrogenase (M/SCHAD) deficiency; and very long-chain acyl-CoA dehydrongenase (VLCAD) deficiency.
In some embodiments, methods of treating neurodegenerative diseases are provided. In some embodiments, the method comprises administering to a subject an effective amount of an inhibitor of USP30.
In some embodiments, the neurodegenerative disease is selected from Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS), Huntington's disease, ischemia, stroke, dementia with Lewy bodies, and frontotemporal dementia.
In some embodiments, methods of treating Parkinson's disease are provided. In some embodiments, the method comprises administering to a subject an effective amount of an inhibitor of USP30.
In some embodiments, methods of treating conditions involving cells undergoing oxidative stress are provided. In some embodiments, the method comprises administering to a subject an effective amount of an inhibitor of USP30.
In some embodiments involving treatment of a subject, the subject comprises a pathogenic mutation in Parkin, a pathogenic mutation in PINK1, or a pathogenic mutation in Parkin and a pathogenic mutation in PINK1 in at least a portion of the subject's cells. In some embodiments, the pathogenic mutation in Parkin is selected from the mutations in Table 1. In some embodiments, the pathogenic mutation in PINK1 is selected from the mutations in Table 2.
In some embodiments, the inhibitor of USP30 is administered orally, intramuscularly, intravenously, intraarterially, intraperitoneally, or subcutaneously. In some embodiments, the method comprises administering at least one additional therapeutic agent. In some embodiments, the at least one additional therapeutic agent is selected from levodopa, a dopamine agonist, a monoamino oxygenase (MAO) B inhibitor, a catechol O-methyltransferase (COMT) inhibitor, an anticholinergic, amantadine, riluzole, a cholinesterase inhibitor, memantine, tetrabenazine, an antipsychotic, clonazepam, diazepam, an antidepressant, and an anti-convulsant.
In any of the methods described herein, the inhibitor of USP30 may be an inhibitor of USP30 expression. Nonlimiting exemplary inhibitors of USP30 expression include antisense oligonucleotides and short interfering RNAs (siRNAs). In any of the methods described herein, the inhibitor of USP30 may be an inhibitor of USP30 activity. Nonlimiting exemplary inhibitors of USP30 activity include antibodies, peptides, peptibodies, aptamers, and small molecules.
In some embodiments, a peptide inhibitor of USP30 comprises the amino acid sequence:
wherein:
X1 is selected from L, M, A, S, and V;
X2 is selected from Y, D, E, I, L, N, and S;
X3 is selected from F, I, and Y;
X4 is selected from F, I, and Y;
X5 is selected from D and E;
X6 is selected from L, M, V, and P;
X7 is selected from S, N, D, A, and T;
X8 is selected from Y, D, F, N, and W;
X9 is selected from G, D, and E;
X10 is selected from Y and F;
X10 is selected from L, V, M, Q, and W; and
X12 is selected from F, L, C, V, and Y.
In some embodiments, a peptide inhibitor of USP30 peptide comprises an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 95%, or 100% identical to an amino acid sequence selected from SEQ ID NOs: 1 to 22. In some embodiments, the peptide inhibits USP30 with an IC50 of less than 10 μM. In some embodiments, the IC50 of a peptide inhibitor of USP30 for at least one, at least two, or at least three peptidases selected from USP7, USP5, UCHL3, and USP2 is greater than 20 μM, greater than 30 μM, greater than 40 μM, or greater than 50 μM.
In some embodiments, an antisense oligonucleotide comprises a nucleotide sequence that is at least at least 80%, at least 85%, at least 90%, at least 95%, or 100% complementary to a region of USP30 mRNA and/or a region of USP30 pre-mRNA. In some embodiments, the region of USP30 mRNA or region of USP30 pre-mRNA is at least at least 10, at least 15, at least 20, at least 25, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, or at least 100 nucleotides long. In some embodiments, the antisense oligonucleotide is 10 to 500 nucleotides long, or 10 to 400 nucleotides long, or 10 to 300 nucleotides long, or 10 to 200 nucleotides long, or 10 to 100 nucleotides long, or 15 to 100 nucleotides long, or 10 to 50 nucleotides long, or 15 to 50 nucleotides long. An antisense oligonucleotide may comprise one or more non-nucleotide components.
In some embodiments, an siRNA comprises a nucleotide sequence that is at least at least 80%, at least 85%, at least 90%, at least 95%, or 100% identical to a region of USP30 mRNA and/or a region of USP30 pre-mRNA. In some embodiments, the region of USP30 mRNA or region of USP30 pre-mRNA is at least at least 10, at least 15, at least 20, or at least 25 nucleotides long. In some embodiments, the siRNA is 10 to 200 nucleotides long, or 10 to 100 nucleotides long, or 15 to 100 nucleotides long, or 10 to 60 nucleotides long, or 15 to 60 nucleotides long, or 10 to 50 nucleotides long, or 15 to 50 nucleotides long, or 10 to 30 nucleotides long, or 15 to 30 nucleotides long. In some embodiments, an siRNA is an shRNA.
An embodiment of the present invention is an inhibitor of USP30 for the treatment of a condition involving a mitochondrial defect in a subject. In a particular embodiment the condition involving a mitochondrial defect is selected from a condition involving a mitophagy defect, a condition involving a mutation in mitochondrial DNA, a condition involving mitochondrial oxidative stress, a condition involving a defect in mitochondrial shape or morphology, a condition involving a defect in mitochondrial membrane potential, and a condition involving a lysosomal storage defect. in another particular embodiment the condition involving a mitochondrial defect is selected from a neurodegenerative disease; mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome; Leber's hereditary optic neuropathy (LHON); neuropathy, ataxia, retinitis pigmentosa-maternally inherited Leigh syndrome (NARP-MILS); Danon disease; ischemic heart disease leading to myocardial infarction; multiple sulfatase deficiency (MSD); mucolipidosis II (ML II); mucolipidosis III (ML III); mucolipidosis IV (ML IV); GM1-gangliosidosis (GM1); neuronal ceroid-lipofuscinoses (NCL1); Alpers disease; Barth syndrome; Beta-oxidation defects; carnitine-acyl-carnitine deficiency; carnitine deficiency; creatine deficiency syndromes; co-enzyme Q10 deficiency; complex I deficiency; complex II deficiency; complex III deficiency; complex IV deficiency; complex V deficiency; COX deficiency; chronic progressive external ophthalmoplegia syndrome (CPEO); CPT I deficiency; CPT II deficiency; glutaric aciduria type II; Kearns-Sayre syndrome; lactic acidosis; long-chain acyl-CoA dehydrongenase deficiency (LCHAD); Leigh disease or syndrome; lethal infantile cardiomyopathy (LIC); Luft disease; glutaric aciduria type II; medium-chain acyl-CoA dehydrongenase deficiency (MCAD); myoclonic epilepsy and ragged-red fiber (MERRF) syndrome; mitochondrial recessive ataxia syndrome; mitochondrial cytopathy; mitochondrial DNA depletion syndrome; myoneurogastointestinal disorder and encephalopathy; Pearson syndrome; pyruvate carboxylase deficiency; pyruvate dehydrogenase deficiency; POLG mutations; medium/short-chain 3-hydroxyacyl-CoA dehydrogenase (M/SCHAD) deficiency; and very long-chain acyl-CoA dehydrongenase (VLCAD) deficiency. In a more particular embodiment the neurodegenerative disease is selected from Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS), Huntington's disease, ischemia, stroke, dementia with Lewy bodies, and frontotemporal dementia.
Another embodiment of the present invention is an inhibitor of USP30 for the treatment of a neurodegenerative disease in a subject comprising administering to the subject. In a particular embodiment, the neurodegenerative disease is selected from Parkinson's disease, Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis (ALS), ischemia, stroke, dementia with Lewy bodies, and frontotemporal dementia.
Also an embodiment of the present invention is an inhibitor of USP30 for the treatment of Parkinson's disease in a subject.
In another embodiment of the present invention, the inhibitor of USP30 is administered orally, intramuscularly, intravenously, intraarterially, intraperitoneally, or subcutaneously.
In a particular embodiment of the present invention. the inhibitor of USP30 for the use in a treatment as described herein is combined with at least one additional therapeutic agent. in a further particular embodiment, the at least one additional therapeutic agent is selected from levodopa, a dopamine agonist, a monoamino oxygenase (MAO) B inhibitor, a catechol O-methyltransferase (COMT) inhibitor, an anticholinergic, amantadine, riluzole, a cholinesterase inhibitor, memantine, tetrabenazine, an antipsychotic, clonazepam, diazepam, an antidepressant, and an anti-convulsant.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
The present inventors have identified USP30, a mitochondria-localized deubiquitinase (DUB) as an atagonist of Parkin-mediated mitophagy. USP30, through its deubiquitinase activity, counteracts ubiquitination and degradation of damaged mitochondria, and inhibition of USP30 rescues mitophagy defects caused by mutant Parkin. Further, USP30 inhibition of USP30 decreases oxidative stress and provides protection against the mitochondrial toxin, rotenone. Since damaged mitochondria are more likely to accumulate Parkin, USP30 inhibition should preferentially clear unhealthy mitochondria. In addition to neurons (such as substantia nigra neurons, which are especially vulnerable to mitochondria dysfunction in Parkinson's disease), long-lived metabolically active cells such as cardiomyocytes also rely on an efficient mitochondria quality control system. In this context, Parkin has been shown to protect cardiomyocytes against ischemia/reperfusion injury through activating mitophagy and clearing damaged mitochondria in response to ischemic stress. Thus, inhibitors of USP30 are provided for us in treating a conditions involving mitochondrial defects, including neurological conditions, cardiac conditions, and systemic conditions.
An “inhibitor” refers to an agent capable of blocking, neutralizing, inhibiting, abrogating, reducing and/or interfering with one or more of the activities of a target and/or reducing the expression of the target protein (or the expression of nucleic acids encoding the target protein) Inhibitors include, but are not limited to, antibodies, polypeptides, peptides, nucleic acid molecules, short interfering RNAs (siRNAs) and other inhibitory RNAs, small molecules (e.g., small inorganic molecules), polysaccharides, polynucleotides, antisense oligonucleotides, aptamers, and peptibodies. An inhibitor may decrease the activity and/or expression of a target protein by at least 10% (e.g., by at least 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or even 100% decrease) as compared to the expression and/or activity of the target protein that is untreated with the inhibitor.
An “inhibitor of USP30” refers to an agent capable of blocking, neutralizing, inhibiting, abrogating, reducing and/or interfering with one or more of the activities of USP30 and/or reducing the expression of USP30 (or the expression of nucleic acids encoding USP30). In some embodiments, an inhibitor of USP30 reduces the deubiquitinase activity of USP30. In some embodiments, an inhibitor of USP30 reduces deubiquitinase activity by at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or 100%. Deubiquitinase activity may be reduced by an inhibitor by any mechanism, including, but not limited to, interfering with the active site of USP30, interfering with target recognition, altering the conformation of USP30, interfering with proper subcellular localization of USP30, etc. In some embodiments, an inhibitor of USP30 inhibits USP30 expression, which may be expression as the mRNA (e.g., it inhibits transcription of the USP30 gene to produce USP30 mRNA) and/or protein level (e.g., it inhibits translation of the USP30 mRNA to produce USP30 protein). In some embodiments, an inhibitor of USP30 expression reduces the level of USP30 protein by at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or 100%.
The terms “mitophagy” and “mitochondrial degradation” are used interchangeably to refer to the regulated degradation of mitochondria through the lysosomal machinery of a cell.
A “condition involving a mitochondrial defect” refers to a condition involving a defect or defects in mitochondrial function, mitochondrial shape/morphology, mitochondrial membrane potential, and/or mitophagy in a cell population. Conditions involving a mitochondrial defect include, but are not limited to, conditions involving a defect in mitophagy, such that mitophagy occurs in the cell population at a slower rate or to a lesser extent than in a normal cell population. In some embodiments, the defect in mitophagy is accompanied by other mitochondrial defects such that the decreased mitophagy results in the increased presence of defective mitochondria. Conditions involving a mitochondrial defect also include, but are not limited to, conditions involving mutations in mitochondrial DNA that result in altered mitochondrial function. Conditions involving a mitochondrial defect also include conditions involving mitochondrial oxidative stress, in which increased levels of reactive oxygen species (ROS) and/or reactive nitrogen species (RNS) in a cell are associated with protein aggregation and/or mitochondrial dysfunction. Mitochondrial oxidative stress may result in mitochondrial dysfunction, or mitochondrial dysfunction may result in oxidative stress. Conditions involving a mitochondrial defect also include, but are not limited to, conditions involving defects in mitochondrial shape/morphology and conditions involving defects in mitochondrial membrane potential. Exemplary conditions involving mitochondrial defects include, but are not limited to, neurodegenerative diseases (such as Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis (ALS), Alzheimer's disease, ischemia, stroke, dementia with Lewy bodies, and frontotemporal dementia); mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome; Leber's hereditary optic neuropathy (LHON); neuropathy, ataxia, retinitis pigmentosa-maternally inherited Leigh syndrome (NARP-MILS); Danon disease; myoclonic epilepsy with ragged red fibers (MERFF) syndrome; ischemic heart disease leading to myocardial infarction; multiple sulfatase deficiency (MSD); mucolipidosis II (ML II); mucolipidosis III (ML III); mucolipidosis IV (ML IV); GM1-gangliosidosis (GM1); neuronal ceroid-lipofuscinoses (NCL1); Alpers disease; Barth syndrome; Beta-oxidation defects; carnitine-acyl-carnitine deficiency; carnitine deficiency; creatine deficiency syndromes; co-enzyme Q10 deficiency; complex I deficiency; complex II deficiency; complex III deficiency; complex IV deficiency; complex V deficiency; COX deficiency; chronic progressive external ophthalmoplegia syndrome (CPEO); CPT I deficiency; CPT II deficiency; glutaric aciduria type II; Kearns-Sayre syndrome; lactic acidosis; long-chain acyl-CoA dehydrongenase deficiency (LCHAD); Leigh disease or syndrome; lethal infantile cardiomyopathy (LIC); Luft disease; glutaric aciduria type II; medium-chain acyl-CoA dehydrongenase deficiency (MCAD); myoclonic epilepsy and ragged-red fiber (MERRF) syndrome; mitochondrial recessive ataxia syndrome; mitochondrial cytopathy; mitochondrial DNA depletion syndrome; myoneurogastointestinal disorder and encephalopathy; Pearson syndrome; pyruvate carboxylase deficiency; pyruvate dehydrogenase deficiency; POLG mutations; medium/short-chain 3-hydroxyacyl-CoA dehydrogenase (M/SCHAD) deficiency; and very long-chain acyl-CoA dehydrongenase (VLCAD) deficiency.
A “pathogenic mutation” in Parkin or PINK1 refers to a mutation or mutations in the respective protein or gene that results in reduced activity in a cell, and may involve loss of function and/or gain of function (such as dominant negative mutations, for example, Parkin Q311stop). Such reduced activity in a cell may include, but is not limited to, reduced enzymatic activity (such as reduced ubiquitination or kinase activity), reduced activity due to the presence of a dominant negative mutant protein, reduced binding to another cellular factor, reduced activity due to subcellular localization changes, and/or reduced activity due to reduced levels of protein in the cell or in a cellular compartment. In some embodiments, a pathogenic mutation in Parkin and/or PINK1 results in reduced ubiquitination of mitochondria, which may result in reduced mitophagy. Pathogenic mutations may also occur outside of the coding region of the protein, e.g., in an intron (affecting, for example, splicing), the promoter, the 5′ untranslated region, the 3′ untranslated region, etc. Further, Parkin mutations may involve substitutions, deletions, insertions, duplications, etc., or any combination of those. Nonlimiting exemplary pathogenic mutations in Parkin are shown in Table 1. Nonlimiting exemplary pathogenic mutations in PINK1 protein are shown in Table 2. Databases of Parkinson's disease mutations are publicly available, such as Parkinson Disease Mutation Database, http://www.molgen.ua.ac.be/PDmutDB/.
The term “oxidative stress” refers to an increase in reactive oxygen species (ROS) and/or reactive nitrogen species (RNS) in a cell. In some embodiments, oxidative stress leads to protein aggregation and/or mitochondrial dysfunction. In some embodiments, mitochondrial dysfunction leads to oxidative stress.
The term “USP30,” as used herein, refers to any native USP30 (“ubiquitin specific peptidase 30” or “ubiquitin specific protease 30”) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed USP30 as well as any form of USP30 that results from processing in the cell. The term also encompasses naturally occurring variants of USP30, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human USP30 is shown in SEQ ID NO: 26 (Table 4).
The term “Parkin” as used herein, refers to any native Parkin from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed Parkin as well as any form of Parkin that results from processing in the cell. The term also encompasses naturally occurring variants of Parkin, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human Parkin is shown in SEQ ID NO: 29 (Table 4).
The term “PINK1” as used herein, refers to any native PINK1 (PTEN-induced putative kinase protein 1) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed PINK1 as well as any form of PINK1 that results from processing in the cell. The term also encompasses naturally occurring variants of PINK1, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human PINK1 is shown in SEQ ID NO: 30 (Table 4).
The term “Tom20” as used herein, refers to any native Tom20 from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed Tom20 as well as any form of Tom20 that results from processing in the cell. The term also encompasses naturally occurring variants of Tom20, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human Tom20 is shown in SEQ ID NO: 27 (Table 4).
The terms “MIRO1” and “MIRO” as used herein, refer to any native MIRO1 (mitochondrial Rho GTPase 1) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed MIRO1 as well as any form of MIRO1 that results from processing in the cell. The term also encompasses naturally occurring variants of MIRO1, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human MIRO1 is shown in SEQ ID NO: 28 (Table 4).
The term “MUL1” as used herein, refers to any native MUL1 (mitochondrial ubiquitin ligase activator of NFκB) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed MUL1 as well as any form of MUL1 that results from processing in the cell. The term also encompasses naturally occurring variants of MUL1, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human MUL1 is shown in SEQ ID NO: 32 (Table 4).
The term “ASNS” as used herein, refers to any native ASNS (asparagine synthetase [glutamine hydrolyzing]) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed ASNS as well as any form of ASNS that results from processing in the cell. The term also encompasses naturally occurring variants of ASNS, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human ASNS is shown in SEQ ID NO: 33 (Table 4).
The term “FKBP8” as used herein, refers to any native FKBP8 (FK506 binding protein 8) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed ASNS as well as any form of FKBP8 that results from processing in the cell. The term also encompasses naturally occurring variants of FKBP8, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human FKBP8 is shown in SEQ ID NO: 34 (Table 4).
The term “TOM70” as used herein, refers to any native TOM70 (translocase of outer membrane 70 kDa subunit) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed TOM70 as well as any form of TOM70 that results from processing in the cell. The term also encompasses naturally occurring variants of TOM70, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human TOM70 is shown in SEQ ID NO: 35 (Table 4).
The term “MAT2B” as used herein, refers to any native MAT2B (methionine adenosyltransferase 2 subunit beta) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed MAT2B as well as any form of MAT2B that results from processing in the cell. The term also encompasses naturally occurring variants of MAT2B, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human MAT2B is shown in SEQ ID NO: 36 (Table 4).
The term “PRDX3” as used herein, refers to any native PRDX3 (peroxiredoxin III) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed PRDX3 as well as any form of PRDX3 that results from processing in the cell. The term also encompasses naturally occurring variants of PRDX3, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human PRDX3 is shown in SEQ ID NO: 37 (Table 4).
The term “IDE” as used herein, refers to any native IDE (insulin degrading enzyme) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed IDE as well as any form of IDE that results from processing in the cell. The term also encompasses naturally occurring variants of IDE, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human IDE is shown in SEQ ID NO: 38 (Table 4).
The term “VDAC1” as used herein, refers to any native VDAC1 (voltage-dependent anion selective channel protein 1) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed VDAC1 as well as any form of VDAC1 that results from processing in the cell. The term also encompasses naturally occurring variants of VDAC1, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human VDAC1 is shown in SEQ ID NO: 39 (Table 4).
The term “VDAC2” as used herein, refers to any native VDAC2 (voltage-dependent anion selective channel protein 2) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed VDAC2 as well as any form of VDAC2 that results from processing in the cell. The term also encompasses naturally occurring variants of VDAC2, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human VDAC2 is shown in SEQ ID NO: 44 (Table 4).
The term “VDAC3” as used herein, refers to any native VDAC3 (voltage-dependent anion selective channel protein 3) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed VDAC3 as well as any form of VDAC3 that results from processing in the cell. The term also encompasses naturally occurring variants of VDAC3, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human VDAC3 is shown in SEQ ID NO: 45 (Table 4).
The term “IP05” as used herein, refers to any native IP05 (importin 5) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed IP05 as well as any form of IP05 that results from processing in the cell. The term also encompasses naturally occurring variants of IP05, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human IP05 is shown in SEQ ID NO: 40 (Table 4).
The term “PTH2” as used herein, refers to any native PTH2 (peptidyl-tRNA hydrolase 2, mitochondrial) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed PTH2 as well as any form of PTH2 that results from processing in the cell. The term also encompasses naturally occurring variants of PTH2, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human PTH2 is shown in SEQ ID NO: 41 (Table 4).
The term “PSD13” as used herein, refers to any native PSD13 (26S proteasome non-ATPase regulatory subunit 13) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed PSD13 as well as any form of PSD13 that results from processing in the cell. The term also encompasses naturally occurring variants of PSD13, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human PSD13 is shown in SEQ ID NO: 42 (Table 4).
The term “UBP13” as used herein, refers to any native UBP13 (ubiquitin carboxyl-terminal hydrolase 13) from any vertebrate source, including mammals such as primates (e.g. humans) and rodents (e.g., mice and rats), unless otherwise indicated. The term encompasses “full-length,” unprocessed UBP13 as well as any form of UBP13 that results from processing in the cell. The term also encompasses naturally occurring variants of UBP13, e.g., splice variants or allelic variants. The amino acid sequence of an exemplary human UBP13 is shown in SEQ ID NO: 43 (Table 4).
The term “package insert” is used to refer to instructions customarily included in commercial packages of therapeutic products, that contain information about the indications, usage, dosage, administration, combination therapy, contraindications and/or warnings concerning the use of such therapeutic products.
An “individual” or “subject” is a mammal. Mammals include, but are not limited to, domesticated animals (e.g., cows, sheep, cats, dogs, and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In certain embodiments, the individual or subject is a human.
“Percent (%) amino acid sequence identity” with respect to a reference polypeptide sequence is defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the reference polypeptide sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared. For purposes herein, however, % amino acid sequence identity values are generated using the sequence comparison computer program ALIGN-2. The ALIGN-2 sequence comparison computer program was authored by Genentech, Inc., and the source code has been filed with user documentation in the U.S. Copyright Office, Washington D.C., 20559, where it is registered under U.S. Copyright Registration No. TXU510087. The ALIGN-2 program is publicly available from Genentech, Inc., South San Francisco, Calif., or may be compiled from the source code. The ALIGN-2 program should be compiled for use on a UNIX operating system, including digital UNIX V4.0D. All sequence comparison parameters are set by the ALIGN-2 program and do not vary.
In situations where ALIGN-2 is employed for amino acid sequence comparisons, the % amino acid sequence identity of a given amino acid sequence A to, with, or against a given amino acid sequence B (which can alternatively be phrased as a given amino acid sequence A that has or comprises a certain % amino acid sequence identity to, with, or against a given amino acid sequence B) is calculated as follows:
100 times the fraction X/Y
where X is the number of amino acid residues scored as identical matches by the sequence alignment program ALIGN-2 in that program's alignment of A and B, and where Y is the total number of amino acid residues in B. It will be appreciated that where the length of amino acid sequence A is not equal to the length of amino acid sequence B, the % amino acid sequence identity of A to B will not equal the % amino acid sequence identity of B to A. Unless specifically stated otherwise, all % amino acid sequence identity values used herein are obtained as described in the immediately preceding paragraph using the ALIGN-2 computer program.
The term “pharmaceutical formulation” refers to a preparation which is in such form as to permit the biological activity of an active ingredient contained therein to be effective, and which contains no additional components which are unacceptably toxic to a subject to which the formulation would be administered.
A “pharmaceutically acceptable carrier” refers to an ingredient in a pharmaceutical formulation, other than an active ingredient, which is nontoxic to a subject. A pharmaceutically acceptable carrier includes, but is not limited to, a buffer, excipient, stabilizer, or preservative.
As used herein, “treatment” (and grammatical variations thereof such as “treat” or “treating”) refers to clinical intervention in an attempt to alter the natural course of the individual being treated, and can be performed either for prophylaxis or during the course of clinical pathology. Desirable effects of treatment include, but are not limited to, preventing occurrence or recurrence of disease, alleviation of symptoms, diminishment of any direct or indirect pathological consequences of the disease, preventing metastasis, decreasing the rate of disease progression, amelioration or palliation of the disease state, and remission or improved prognosis. In some embodiments, antibodies of the invention are used to delay development of a disease or to slow the progression of a disease.
Administration “in combination with” one or more further therapeutic agents includes simultaneous (concurrent) and consecutive administration, in any order.
An “effective amount” of an agent, e.g., a pharmaceutical formulation, refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic or prophylactic result.
The term “vector,” as used herein, refers to a nucleic acid molecule capable of propagating another nucleic acid to which it is linked. The term includes the vector as a self-replicating nucleic acid structure as well as the vector incorporated into the genome of a host cell into which it has been introduced. Certain vectors are capable of directing the expression of nucleic acids to which they are operatively linked. Such vectors are referred to herein as “expression vectors.”
The terms “host cell,” “host cell line,” and “host cell culture” are used interchangeably and refer to cells into which exogenous nucleic acid has been introduced, including the progeny of such cells. Host cells include “transformants” and “transformed cells,” which include the primary transformed cell and progeny derived therefrom without regard to the number of passages. Progeny may not be completely identical in nucleic acid content to a parent cell, but may contain mutations. Mutant progeny that have the same function or biological activity as screened or selected for in the originally transformed cell are included herein.
In various aspects, the invention is based, in part, on inhibitors of USP30 and methods of treating diseases and disorders comprising inhibiting USP30.
A. Exemplary Inhibitors of USP30
The present invention is based in part on the discovery that inhibitors of USP30 activity and/or expression are effective for increasing and/or restoring mitochondrial ubiquitination and mitophagy. In some embodiments, inhibitors of USP30 are effective for treating neurodegenerative diseases, such as Parkinson's disease, as well as conditions that involve mitochondrial defects, such as those involving mitophagy defects, mutations in mitochondrial DNA, mitochondrial oxidative stress, and/or lysosomal storage defects.
Inhibitors of USP30 include inhibitors of USP30 activity and inhibitors of USP30 expression. Nonlimiting exemplary such inhibitors include antisense oligonucleotides, short interfering RNAs (siRNAs), antibodies, peptides, peptibodies, aptamers, and small molecules. In some embodiments, antisense oligonucleotides or short interfering RNAs (siRNAs) may be used to inhibit USP30 expression. In some embodiments, antibodies, peptides, peptibodies, aptamers, and small molecules may be used to inhibit USP30 activity. Some nonlimiting examples of inhibitors of USP30 are described herein. Further inhibitors can be identified using standard methods in the art, including those discussed herein.
Antisense Oligonucleotides
In some embodiments, antisense oligonucleotides that hybridize to USP30 mRNA and/or USP30 pre-mRNA are provided. A nonlimiting exemplary human mRNA sequence encoding USP30 is shown in SEQ ID NO: 30 (Table 4). In some embodiments, an antisense oligonucleotide hybridizes to a region of USP30 mRNA and/or USP30 pre-mRNA and directs its degradation through RNase H, which cleaves double-stranded RNA/DNA hybrids. By mediating cleavage of USP30 mRNA and/or USP30 pre-mRNA, an antisense oligonucleotide may reduce the amount of USP30 protein in a cell (i.e., may inhibit expression of USP30). In some embodiments, an antisense oligonucleotide does not mediate degradation through RNase H, but rather “blocks” translation of the mRNA, e.g., through interference with translational machinery binding or processivity, or “blocks” proper splicing of the pre-mRNA, e.g., through interference with the splicing machinery and/or accessibility of a splice site. In some embodiments, an antisense oligonucleotide may mediate degradation of an mRNA and/or pre-mRNA through a mechanism other than RNase H Any inhibitory mechanism of an antisense oligonucleotide is contemplated herein.
In some embodiments, an antisense oligonucleotide is 10 to 500 nucleotides long, or 10 to 400 nucleotides long, or 10 to 300 nucleotides long, or 10 to 200 nucleotides long, or 10 to 100 nucleotides long, or 15 to 100 nucleotides long, or 10 to 50 nucleotides long, or 15 to 50 nucleotides long. In various embodiments, an antisense oligonucleotide hybridizes to a region of the USP30 mRNA and/or pre-mRNA comprising at least 10, at least 15, at least 20, at least 25, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, or at least 100 nucleotides. Further, in various embodiments, an antisense oligonucleotide need not be 100% complementary to a region USP30 mRNA and/or a region of USP30 pre-mRNA, but may have 1 or more mismatches. Thus, in some embodiments, an antisense oligonucleotide is at least 80% complementary, at least 85% complementary, at least 90% complementary, at least 95% complementary, or 100% complementary to a region of USP30 mRNA and/or a region of USP30 pre-mRNA. In some embodiments, the region of USP30 mRNA or the region of USP pre-mRNA is at least at least 10, at least 15, at least 20, at least 25, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, or at least 100 nucleotides long.
Antisense oligonucleotides may comprise modifications to one or more of the internucleoside linkages, sugar moieties, and/or nucleobases. Further, the sequence of nucleotides may be interrupted by non-nucleotide components, and/or non-nucleotide components may be attached at one or both ends of the oligonucleotide.
Nonlimiting exemplary nucleotide modifications include sugar modifications, in which any of the hydroxyl groups ordinarily present in the sugars may be replaced, for example, by phosphonate groups, phosphate groups, protected by standard protecting groups, or activated to prepare additional linkages to additional nucleotides, or may be conjugated to solid supports. The 5′ and 3′ terminal OH can be phosphorylated or substituted with amines or organic capping groups moieties of from 1 to 20 carbon atoms. Other hydroxyls may also be derivatized to standard protecting groups. Oligonucleotides can also contain analogous forms of ribose or deoxyribose sugars that are generally known in the art, including, for example, 2′-O-methyl-2′-0-allyl, 2′-fluoro- or 2′-azido-ribose, carbocyclic sugar analogs, a-anomeric sugars, epimeric sugars such as arabinose, xyloses or lyxoses, pyranose sugars, furanose sugars, sedoheptuloses, acyclic analogs and abasic nucleoside analogs such as methyl riboside. One or more phosphodiester linkages may be replaced by modified internucleoside linkages. These modified internucleoside linkages include, but are not limited to, embodiments wherein phosphate is replaced by P(O)S (“thioate”), P(S)S (“dithioate”), (O)NR2 (“amidate”), P(O)R, P(O)OR′, CO or CH2 (“formacetal”), in which each R or R′ is independently H or substituted or unsubstituted alkyl (1-20 C) optionally containing an ether (—O—) linkage, aryl, alkenyl, cycloalkyl, cycloalkenyl or araldyl. Not all linkages in a polynucleotide need be identical. The preceding description applies to all oligonucleotides referred to herein, including antisense oligonucleotides and siRNA.
In some embodiments, one or more internucleoside linkages in an antisense oligonucleotide are phosphorothioates. In some embodiments, one or more sugar moieties in an antisense oligonucleotide comprise 2′ modifications, such as 2′-O-alkyl (such as 2′-OMe) and 2′-fluoro; or are bicyclic sugar moieties (such as LNA). Nonlimiting exemplary nucleobase modifications include 5-methylcytosine. An antisense oligonucleotide may comprise more than one type of modification within a single oligonucleotide. That is, as a nonlimiting example, an antisense oligonucleotide may comprise 2′-O alkyl modifications, bicyclic nucleotides, and phosphorothioate linkages in the same oligonucleotide. In some embodiments, an antisense oligonucleotide is a “gapmer.” Gapmers comprise a central region of deoxyribonucleotides for mediating RNase H cleavage, and 5′ and 3′ “wings” comprising modified sugar moieties that increase the stability of the duplex.
Antisense oligonucleotide design and mechanisms are described, e.g., in van Roon-Mom et al., Methods Mol. Biol., 867: 79-96 (20120); Prakash, Chem. Biodivers., 8: 1616-1641 (2011); Yamamoto et al., Future Med. Chem., 3: 339-365 (2011); Chan et al., Clin. Exper. Pharmacol. Physiol., 33: 533-540 (2006); Kurreck et al., Nucl. Acids Res., 30: 1911-1918 (2002); Kurreck, Eur. J. Biochem., 270: 1628-1644 (2003); Geary, Expert Opin. Drug Metab. Toxicol., 5: 381-391 (2009); “Designing Antisense Oligonucleotides,” available online from Integrated DNA Technologies (2011).
Short Interfering RNAs (siRNAs)
In some embodiments, the expression of USP30 is inhibited with a short interfering RNA (siRNA). As used herein, siRNAs are synonymous with double-stranded RNA (dsRNA) and include double-stranded RNA oligomers with or without hairpin structures at each end (also referred to as small hairpin RNA, or shRNA). Short interfering RNAs are also known as small interfering RNAs, silencing RNAs, short inhibitory RNA, and/or small inhibitory RNAs, and these terms are considered to be equivalent herein.
The term “short-interfering RNA (siRNA)” refers to small double-stranded RNAs that interfere with gene expression. siRNAs are mediators of RNA interference, the process by which double-stranded RNA silences homologous genes. In some embodiments, siRNAs are comprised of two single-stranded RNAs of about 15-25 nucleotides in length that form a duplex, which may include single-stranded overhang(s). In some embodiments, siRNAs are comprised of a single RNA that forms a hairpin structure that includes a double-stranded portion that may be 15-25 nucleotides in length and may include a single-stranded overhang. Such hairpin siRNAs may be referred to as a short hairpin RNA (shRNA). Processing of the double-stranded RNA by an enzymatic complex, for example, polymerases, may result in cleavage of the double-stranded RNA to produce siRNAs. The antisense strand of the siRNA is used by an RNA interference (RNAi) silencing complex to guide mRNA cleavage, thereby promoting mRNA degradation. To silence a specific gene using siRNAs, for example, in a mammalian cell, a base pairing region is selected to avoid chance complementarity to an unrelated mRNA. RNAi silencing complexes have been identified in the art, such as, for example, by Fire et al., Nature 391:806-811, 1998, and McManus et al., Nat. Rev. Genet. 3(10):737-747, 2002.
In some embodiments, small interfering RNAs comprise at least about 10 to about 200 nucleotides, including at least about 16 nucleotides, at least about 17 nucleotides, at least about 18 nucleotides, at least about 19 nucleotides, at least about 20 nucleotides, at least about 21 nucleotides, at least about 22 nucleotides, at least about 23 nucleotides, at least about 24 nucleotides, at least about 25 nucleotides, at least about 26 nucleotides, at least about 27 nucleotides, at least about 28 nucleotides, at least about 29 nucleotides, at least about 30 nucleotides, at least about 35 nucleotides, at least about 40 nucleotides, at least about 45 nucleotides, at least about 50 nucleotides, at least about 55 nucleotides, at least about 60 nucleotides, at least about 65 nucleotides, at least about 70 nucleotides, at least about 75 nucleotides, at least about 80 nucleotides, at least about 85 nucleotides, at least about 90 nucleotides, at least about 95 nucleotides, at least about 100 nucleotides, at least about 110 nucleotides, at least about 120 nucleotides, at least about 130 nucleotides, at least about 140 nucleotides, at least about 150 nucleotides, or greater than 150 nucleotides. In some embodiments, an siRNA is 10 to 200 nucleotides long, or 10 to 100 nucleotides long, or 15 to 100 nucleotides long, or 10 to 60 nucleotides long, or 15 to 60 nucleotides long, or 10 to 50 nucleotides long, or 15 to 50 nucleotides long, or 10 to 30 nucleotides long, or 15 to 30 nucleotides long. In certain embodiments, the siRNA comprises an oligonucleotide from about 21 to about 25 nucleotides in length. In some embodiments, the siRNA molecule is a heteroduplex of RNA and DNA.
As with antisense oligonucleotides, siRNAs can include modifications to the sugar, internucleoside linkages, and/or nucleobases. Nonlimiting exemplary modifications suitable for use in siRNAs are described herein and also, e.g., in Peacock et al., J. Org. Chem., 76: 7295-7300 (2011); Bramsen et al., Methods Mol. Biol., 721: 77-103 (2011); Pasternak et al., Org. Biomol. Chem., 9: 3591-3597 (2011); Gaglione et al., Mini Rev. Med. Chem., 10: 578-595 (2010); Chernolovskaya et al., Curr. Opin. Mol. Ther., 12: 158-167 (2010).
A process for inhibiting expression of USP30 in a cell comprises introduction of an siRNA with partial or fully double-stranded character into the cell. In some embodiments, an siRNA comprises a nucleotide sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or 100% identical to a nucleotide sequence found in the USP30 gene coding region or pre-mRNA.
In some embodiments, an siRNA specific to the USP30 gene is synthesized and introduced directly into a subject. In other embodiments, the siRNA can be formulated as part of a targeted delivery system, such as a target specific liposome, which specifically recognizes and delivers the siRNA to an appropriate tissue or cell type. Upon administration of the targeted siRNA to a subject, the siRNA is delivered to the appropriate cell type, thereby increasing the concentration siRNA within the cell type. Depending on the dose of siRNA delivered, this process can provide partial or complete loss of USP30 protein expression.
In other embodiments, an appropriate cell or tissue is provided with an expression construct that comprises a nucleic acid encoding one or both strands of an siRNA that is specific to the USP30 gene. In these embodiments, the nucleic acid that encodes one or both strands of the siRNA can be placed under the control of either a constitutive or a regulatable promoter. In some embodiments, the nucleic acid encodes an siRNA that forms a hairpin structure, e.g., a shRNA.
Various carriers and drug-delivery systems for siRNAs are described, e.g., in Seth et al., Ther. Deliv., 3: 245-261 (2012); Kanasty et al., Mol. Ther., 20: 513-524 (2012); Methods Enzymol., 502: 91-122 (2012); Vader et al., Curr. Top. Med. Chem., 12: 108-119 (2012); Naeye et al., Curr. Top. Med. Chem., 12: 89-96 (2012); Foged, Curr. Top. Med. Chem., 12: 97-107 (2012); Chaturvedi et al., Expert Opin. Drug Deliv., 8: 1455-1468 (2011); Gao et al., Int. J. Nanomed., 6: 1017-1025 (2011); Shegokar et al., Pharmazie., 66: 313-318 (2011); Kumari et al., Expert Opin. Drug Deliv., 11: 1327-1339 (2011).
Antibodies
In some embodiments, an inhibitor of USP30 is an antibody. The term “antibody” is used herein in the broadest sense and encompasses various antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), and antibody fragments so long as they exhibit the desired antigen-binding activity. The term “antibody” as used herein refers to a molecule comprising at least complementarity-determining region (CDR) 1, CDR2, and CDR3 of a heavy chain and at least CDR1, CDR2, and CDR3 of a light chain, wherein the molecule is capable of binding to antigen. The term antibody includes, but is not limited to, fragments that are capable of binding antigen, such as Fv, single-chain Fv (scFv), Fab, Fab′, and (Fab′)2. The term antibody also includes, but is not limited to, chimeric antibodies, humanized antibodies, and antibodies of various species such as mouse, human, cynomolgus monkey, etc.
In some embodiments, an antibody comprises a heavy chain variable region and a light chain variable region, one or both of which may or may not comprise a respective constant region. A heavy chain variable region comprises heavy chain CDR1, framework (FR) 2, CDR2, FR3, and CDR3. In some embodiments, a heavy chain variable region also comprises at least a portion of an FR1, which is N-terminal to CDR1, and/or at least a portion of an FR4, which is C-terminal to CDR3. Similarly, a light chain variable region comprises light chain CDR1, framework (FR) 2, CDR2, FR3, and CDR3. In some embodiments, a light chain variable region also comprises an FR1 and/or an FR4.
Nonlimiting exemplary heavy chain constant regions include γ, δ, and α. Nonlimiting exemplary heavy chain constant regions also include ε and μ. Each heavy constant region corresponds to an antibody isotype. For example, an antibody comprising a γ constant region is an IgG antibody, an antibody comprising a δ constant region is an IgD antibody, and an antibody comprising an a constant region is an IgA antibody. Certain isotypes can be further subdivided into subclasses. For example, IgG antibodies include, but are not limited to, IgG1 (comprising a γ1 constant region), IgG2 (comprising a γ2 constant region), IgG3 (comprising a γ3 constant region), and IgG4 (comprising a γ4 constant region) antibodies. Nonlimiting exemplary light chain constant regions include λ and κ.
In some embodiments, an antibody is a chimeric antibody, which comprises at least one variable region from a first species (such as mouse, rat, cynomolgus monkey, etc.) and at least one constant region from a second species (such as human, cynomolgus monkey, chicken, etc.). The human constant region of a chimeric antibody need not be of the same isotype as the non-human constant region, if any, it replaces. Chimeric antibodies are discussed, e.g., in U.S. Pat. No. 4,816,567; and Morrison et al. Proc. Natl. Acad. Sci. USA 81: 6851-55 (1984).
In some embodiments, an antibody is a humanized antibody, in which at least one amino acid in a framework region of a non-human variable region (such as mouse, rat, cynomolgus monkey, chicken, etc.) has been replaced with the corresponding amino acid from a human variable region. In some embodiments, a humanized antibody comprises at least one human constant region or fragment thereof. In some embodiments, a humanized antibody is an Fab, an scFv, a (Fab′)2, etc. Exemplary humanized antibodies include CDR-grafted antibodies, in which the complementarity determining regions (CDRs) of a first (non-human) species have been grafted onto the framework regions (FRs) of a second (human) species. Humanized antibodies are useful as therapeutic molecules because humanized antibodies reduce or eliminate the human immune response to non-human antibodies (such as the human anti-mouse antibody (HAMA) response), which can result in an immune response to an antibody therapeutic, and decreased effectiveness of the therapeutic. An antibody may be humanized by any method. Nonlimiting exemplary methods of humanization include methods described, e.g., in U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,761; 5,693,762; 6,180,370; Jones et al., Nature 321: 522-525 (1986); Riechmann et al., Nature 332: 323-27 (1988); Verhoeyen et al., Science 239: 1534-36 (1988); and U.S. Publication No. US 2009/0136500.
In some embodiments, an antibody is a human antibody, such as an antibody produced in a non-human animal that comprises human immunoglobulin genes, such as XenoMouse®, and antibodies selected using in vitro methods, such as phage display, wherein the antibody repertoire is based on a human immunoglobulin sequences. Transgenic mice that comprise human immunoglobulin loci and their use in making human antibodies are described, e.g., in Jakobovits et al., Proc. Natl. Acad. Sci. USA 90: 2551-55 (1993); Jakobovits et al., Nature 362: 255-8 (1993); Lonberg et al., Nature 368: 856-9 (1994); and U.S. Pat. Nos. 5,545,807; 6,713,610; 6,673,986; 6,162,963; 5,545,807; 6,300,129; 6,255,458; 5,877,397; 5,874,299; and 5,545,806. Methods of making human antibodies using phage display libraries are described, e.g., in Hoogenboom et al., J. Mol. Biol. 227: 381-8 (1992); Marks et al., J. Mol. Biol. 222: 581-97 (1991); and PCT Publication No. WO 99/10494.
The choice of heavy chain constant region can determine whether or not an antibody will have effector function in vivo. Such effector function, in some embodiments, includes antibody-dependent cell-mediated cytotoxicity (ADCC) and/or complement-dependent cytotoxicity (CDC), and can result in killing of the cell to which the antibody is bound. Typically, antibodies comprising human IgG1 or IgG3 heavy chains have effector function. In some embodiments, effector function is not desirable. In some such embodiments, a human IgG4 or IgG2 heavy chain constant region may be selected or engineered.
Peptides
In some embodiments, an inhibitor of USP30 is a peptide. A peptide is a sequence of amino acids of made up of a single chain of D- or L-amino acids or a mixture of D- and L-amino acids joined by peptide bonds. The amino acid subunits of the peptide may be naturally-occurring amino acids or may be non-naturally occurring amino acids. Many non-naturally occurring amino acids are known in the art and are available commercially. Further, the peptide bonds joining the amino acid subunits may be modified. See, e.g., Sigma-Aldrich; Gentilucci et al., Curr. Pharm. Des. 16: 3185-3203 (2010); US 2008/0318838. Generally, peptides contain at least two amino acid residues and are less than about 50 amino acids in length. In various embodiments, peptide inhibitors may comprise or consist of between 3 and 50, between 5 and 50, between 10 and 50, between 10 and 40, between 10 and 35, between 10 and 30, or between 10 and 25 amino acids. In various embodiments, peptide inhibitors may comprise 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 amino acids. In various embodiments, peptide inhibitors may consist of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 amino acids.
Methods of developing peptides that specifically bind a target molecule are known in the art, including phage display methods. See, e.g., U.S. Pat. No. 5,010,175; WO 1996/023899; WO 1998/015833; Bratkovic, Cell. Mol. Life Sci., 67: 749-767 (2010); Pande et al., Biotech. Adv. 28: 849-858 (2010). In some embodiments, following selection of a peptide, the peptide may be modified, e.g., by incorporating non-natural amino acids and/or peptide bonds. A nonlimiting exemplary method of selecting a peptide inhibitor of USP30 is described herein.
Amino acids that are important for peptide inhibition may be determined, in some embodiments, by alanine scanning mutagenesis. Each residue is replaced in turn with a single amino acid, typically alanine, and the effect on USP30 inhibition is assessed. See, e.g., U.S. Pat. Nos. 5,580,723 and 5,834,250. Truncation analyses may also be used to determine not only the importance of the amino acids at the ends of a peptide, but also the importance of the length of the peptide, on inhibitory activity. In some instances, truncation analysis may reveal a shorter peptide that binds more tightly than the parent peptide. The results of various mutational analyses, such as alanine scanning mutagenesis and truncation analyses, may be used to inform further modifications of an inhibitor peptide.
Nonlimiting exemplary peptide inhibitors are described herein, e.g., in Example 10 and
In some embodiments, a peptide inhibitor comprises the amino acid sequence:
wherein:
X1 is selected from L, M, A, S, and V;
X2 is selected from Y, D, E, I, L, N, and S;
X3 is selected from F, I, and Y;
X4 is selected from F, I, and Y;
X5 is selected from D and E;
X6 is selected from L, M, V, and P;
X7 is selected from S, N, D, A, and T;
X8 is selected from Y, D, F, N, and W;
X9 is selected from G, D, and E;
X10 is selected from Y and F;
X11 is selected from L, V, M, Q, and W; and
X12 is selected from F, L, C, V, and Y;
In some embodiments, the peptide inhibits USP30 with an IC50 of less than 10 μM. In some embodiments, X1 is selected from L and M. In some embodiments, X3 is selected from Y and D. In some embodiments, X3 is F. In some embodiments, X4 is selected from Y and F. In some embodiments, X4 is Y. In some embodiments, X5 is D. In some embodiments, X6 is selected from L and M. In some embodiments, X7 is selected from S, N, and D. In some embodiments, X8 is Y. In some embodiments, X9 is G. In some embodiments, X10 is Y. In some embodiments, X11 is L. In some embodiments, X12 is selected from F and L. In some embodiments, X12 is F.
In some embodiments, a peptide inhibitor comprises the amino acid sequence:
wherein X1 to X12 are as defined above, and XA and XB are each independently any amino acid. In some embodiments, XA is selected from S, A, T, E Q, D, and R. In some embodiments, XB is selected from D, Y, E, H, S, and I.
Peptibodies
In some embodiments, an inhibitor of USP30 is a peptibody. A peptibody is peptide sequence linked to vehicle. In some embodiments, the vehicle portion of the peptibody reduces degradation and/or increases half-life, reduces toxicity, reduces immunogenicity, and/or increases biological activity of the peptide. In some embodiments, the vehicle portion of the peptibody is an antibody Fc domain. Other vehicles include linear polymers (e.g., polyethylene glycol (PEG), polylysine, dextran, etc.); branched-chain polymers (see, e.g., U.S. Pat. No. 4,289,872 and U.S. Pat. No. 5,229,490; WO 1993/0021259); a lipid; a cholesterol group (such as a steroid); a carbohydrate or oligosaccharide; or any natural or synthetic protein, polypeptide, or peptide vehicle. The peptide portion of the peptibody typically binds to the target, e.g., USP30. In some embodiments, the peptide portion of the peptibody is a peptide described herein.
In some embodiments, peptibodies retain certain desirable characteristics of antibodies, such as a long lifetime in plasma and increased affinity for binding partners (for example, due to the dimerization of Fc domains). The production of peptibodies is generally described, e.g., in WO 2000/0024782 and U.S. Pat. No. 6,660,843.
Aptamers
In some embodiments, an inhibitor of USP30 is an aptamer. The term “aptamer” as used herein refers to a nucleic acid molecule that specifically binds to a target molecule, such as USP30. Aptamers can be selected to be highly specific, relatively small in size, and/or non-immunogenic. See, e.g., Ni, et al., Curr. Med. Chem. 18: 4206 (2011). In some embodiments, a aptamer is a small RNA, DNA, or mixed RNA/DNA molecule that forms a secondary and/or tertiary structure capable of specifically binding and inhibiting USP30.
In some embodiments, an aptamer includes one or more modified nucleosides (e.g., nucleosides with modified sugars, modified nucleobases, and/or modified internucleoside linkages), for example, that increase stability in vivo, increase target affinity, increase solubility, increase serum half-life, increase resistance to degradation, and/or increase membrane permeability, etc. In some embodiments, aptamers comprise one or more modified or inverted nucleotides at their termini to prevent terminal degradation, e.g., by an exonuclease.
The generation and therapeutic use of aptamers are well established in the art. See, e.g., U.S. Pat. No. 5,475,096. In some embodiments, aptamers are produced by systematic evolution of ligands by exponential enrichment (SELEX), e.g., as described in Ellington et al., Nature 346: 818 (1990); and Tuerk et al., Science 249: 505 (1990). In some embodiments, aptamers are produced by an AptaBid method, e.g., as described in Berezovski et al., J. Am. Chem. Soc. 130: 913 (2008). Slow off-rate aptamers and methods of selecting such aptamers are described, e.g., in Brody et al., Expert Rev. Mol. Diagn., 10: 1013-22 (2010); and U.S. Pat. No. 7,964,356.
Small Molecules
In some embodiments, small molecule inhibitors of USP30 are provided. In some embodiments, a small molecule inhibitor of USP30 binds to USP30 and inhibits USP30 enzymatic activity (e.g., peptidase activity) and/or interferes with USP30 target binding and/or alters USP30 conformation such that the efficiency of enzymatic activity or target binding is reduced.
A “small molecule” is defined herein to have a molecular weight below about 1000 Daltons, for example, below about 900 Daltons, below about 800 Daltons, below about 700 Daltons, below about 600 Daltons, or below about 500 Daltons. Small molecules may be organic or inorganic, and may be isolated from, for example, compound libraries or natural sources, or may be obtained by derivatization of known compounds.
In some embodiments, a small molecule inhibitor of USP30 is identified by screening a library of small molecules. The generation and screening of small molecule libraries is well known in the art. See, e.g., Thompson et al., Chem. Rev. 96: 555-600 (1996); and the National Institutes of Health Molecular Libraries Program. A combinatorial chemical library, for example, may be formed by mixing a set of chemical building blocks in various combinations, and may result in millions of chemical compounds. For example, the systematic, combinatorial mixing of 100 interchangeable chemical building blocks theoretically results in the synthesis of 100 million tetrameric compounds or 10 billion pentameric compounds. See, e.g., Gallop et al. 1994, J. Med. Chem. 37: 1233-1250). Various other types of small molecule libraries may also be designed and used, such as, for example, natural product libraries. Small molecule libraries can be obtained from various commercial vendors. See, e.g., ChemBridge, Enzo Life Sciences, Sigma-Aldrich, AMRI Global, etc.
To identify a small molecule inhibitor of USP30, in some embodiments, a small molecule library may be screened using an assay described herein. In some embodiments, the characteristics of each small molecule that inhibits USP30 are considered in order to identify features common to the small molecule inhibitors, which may be used to inform further modifications of the small molecules.
In some embodiments, one or more small molecule inhibitors of USP30 identified, for example, in an initial library screen, may be used to generate a subsequent library comprising modifications of the initial small molecule inhibitors. Using this method, subsequent iterations of candidate compounds may be developed that possess greater specificity for USP30 (versus other DUBs), and/or greater binding affinity for USP30, and/or other desirable properties, such as low toxicity, greater solubility, greater cell permeability, etc.
Various small molecule inhibitors of deubiquitylating enzymes are known in the art, some of which are shown in Table 3.
The inhibitors shown in Table 3 and the references cited therein, as well as additional inhibitors known in the art, can form the basis for developing additional deubiquitylation enzyme inhibitors, including specific inhibitors of USP30. See also WO 2007/009715. One skilled in the art can, for example, make modifications to any of the above structures to form a library of putative deubiquitylation enzyme inhibitors and screen for modified compounds with specificity for USP30 using the assays described herein.
B. Assays
Various assays may be used to identify and test inhibitors of USP30. For inhibitors that reduce expression of USP30 protein, any assay that detects protein levels may be suitable for measuring inhibition. As an example, protein levels can be detected by various immunoassays using antibodies that bind USP30, such as ELISA, Western blotting, immunohistochemistry, etc. If an inhibitor affects the subcellular localization of USP30, changes in subcellular localization may be detected, e.g., by immunohistochemistry, or by fractionating cellular components and detecting levels of USP30 in the various fractions using one or more antibodies. For inhibitors that reduce levels of USP30 mRNA, amplification-based assays, such as reverse transcriptase PCR (RT-PCR) may be used to detect changes in mRNA levels.
For inhibitors that affect USP30 enzymatic activity, a nonlimiting exemplary assay is as follows: USP30 is contacted with the inhibitor or candidate inhibitor in the presence of a USP30 substrate. Nonlimiting exemplary USP30 substrates include a Ub-β-galactosidase fusion protein (see, e.g., Quesada et al., Biochem. Biophys. Res. Commun 314:54-62 (2004)), Ub4 chains (e.g., Lys-48- and Lys-63-linked Ub), the linear product of UBIQ gene translation; the post-translationally formed branched peptide bonds in mono- or multi-ubiquitylated conjugates; ubiquitylated remnants resulting from proteasome-mediated degradation, and other small amide or ester adducts. USP30 activity (e.g., processing of Ub substrates) is measured in the presence of USP30 and the inhibitor or candidate inhibitor. This activity is compared with the processing of Ub substrates in the presence USP30 without the inhibitor or candidate inhibitor. If the inhibitor or candidate inhibitor inhibits the activity of USP30, the amount of UB substrate processing will decrease compared to the amount of UB substrate processing in the presence of USP30 without the inhibitor or candidate inhibitor.
A further nonlimiting exemplary assay to determine inhibition and/or specificity is described in Example 10. Briefly, a range of concentrations of inhibitor are mixed with ubiquitin-AMC and USP30 (the inhibitor may be mixed with the substrate, and then USP30 added to start the reaction). If specificity is to be determined, similar reactions may be set up with one or more additional DUBs or ubiquitin C-terminal hydrolases (UCHs) in place of USP30. Immediately after addition of the enzyme, fluorescence is monitored (with excitation at 340 nm and emission at 465 nm). The initial rate of enzymatic activity may be calculated as described in Example 10.
C. Pharmaceutical Formulations
Pharmaceutical formulations of an inhibitor of USP30 as described herein are prepared by mixing such inhibitor having the desired degree of purity with one or more optional pharmaceutically acceptable carriers (Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980)), in the form of lyophilized formulations or aqueous solutions. Pharmaceutically acceptable carriers are generally nontoxic to recipients at the dosages and concentrations employed, and include, but are not limited to: buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid and methionine; preservatives (such as octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride; benzethonium chloride; phenol, butyl or benzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; salt-forming counter-ions such as sodium; metal complexes (e.g. Zn-protein complexes); and/or non-ionic surfactants such as polyethylene glycol (PEG). Exemplary pharmaceutically acceptable carriers herein further include insterstitial drug dispersion agents such as soluble neutral-active hyaluronidase glycoproteins (sHASEGP), for example, human soluble PH-20 hyaluronidase glycoproteins, such as rHuPH20 (HYLENEX®, Baxter International, Inc.). Certain exemplary sHASEGPs and methods of use, including rHuPH20, are described in US Patent Publication Nos. 2005/0260186 and 2006/0104968. In one aspect, a sHASEGP is combined with one or more additional glycosaminoglycanases such as chondroitinases.
The formulation herein may also contain more than one active ingredient as necessary for the particular indication being treated, preferably those with complementary activities that do not adversely affect each other.
Active ingredients may be entrapped in microcapsules prepared, for example, by coacervation techniques or by interfacial polymerization, for example, hydroxymethylcellulose or gelatin-microcapsules and poly-(methylmethacylate) microcapsules, respectively, in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions. Such techniques are disclosed in Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980).
Sustained-release preparations may be prepared. Suitable examples of sustained-release preparations include semipermeable matrices of solid hydrophobic polymers containing the inhibitor, which matrices are in the form of shaped articles, e.g. films, or microcapsules.
The formulations to be used for in vivo administration are generally sterile. Sterility may be readily accomplished, e.g., by filtration through sterile filtration membranes.
D. Therapeutic Methods and Compositions
Any of the inhibitors of USP30 provided herein may be used in methods, e.g., therapeutic methods. In some embodiments, a method of increasing mitophagy in a cell is provided, the method comprising contacting the cell with an inhibitor of USP30 under conditions allowing inhibition of USP30 in the cell. In some embodiments, a method of increasing mitochondrial ubiquitination in a cell is provided, the method comprising contacting the cell with an inhibitor of USP30 under conditions allowing inhibition of USP30 in the cell. Increased mitophagy may be determined, e.g., using immunofluorescence as described in Example 6. Increased ubiquitination may be determined, e.g., by immunoaffinity enrichment of ubiquitinated peptides after trypsin digestion, followed by mass spectrometry as described in Example 5. In some embodiments, an increase in mitochondrial ubiquitination may be determined by comparing the ubiquitination of a mitochondrial proteins a cell or population of cells contacted with an inhibitor of USP30 with the ubiquitination of mitochondrial proteins in a matched cell or population of cells not contacted with the inhibitor.
In some embodiments, increased mitophagy means a reduction in the average number of mitochondria per cell of at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, or at least 75%, in a population of cells contacted with an inhibitor of USP30, as compared to matched population of cells not contacted with the inhibitor. In some embodiments, increased mitochondrial ubiquitination means an increase in overall ubiquitination of mitochondrial proteins in a cell or population of cells contacted with an inhibitor of USP30 of at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 100% (i.e., 2-fold), at least 150%, or at least 200% (i.e., 3-fold) as compared to a matched cell or population of cells not contacted with the inhibitor.
In some embodiments, a method of increasing ubiquitination of at least one protein selected from Tom20, MIRO, MUL1, ASNS, FKBP8, TOM70, MAT2B, PRDX3, IDE, VDAC, IP05, PSD13, UBP13, and PTH2 in a cell is provided, the method comprising contacting the cell with an inhibitor of USP30 under conditions allowing inhibition of USP30 in the cell. In some such embodiments, ubiquitination increases at at least one, at least two, or three amino acids selected from K56, K61, and K68 of Tom 20; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, or eight amino acids selected from K153, K187, K330, K427, K512, K535, K567, and K572 of MIRO. In some such embodiments, ubiquitination increases at at least one, at least two, or three amino acids selected from K56, K61, and K68 of Tom 20; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, or eight amino acids selected from K153, K187, K330, K427, K512, K535, K567, and K572 of MIRO; and/or ubiquitination increases at at least one, at least two, or three amino acids selected from K273, K299, and K52 of MUL1; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, or eight amino acids selected from K249, K271, K273, K284, K307, K317, K334, and K340 of FKBP8; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, or nine amino acids selected from K147, K168, K176, K221, K244, K275, K478, K504, and K556 of ASNS; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten amino acids selected from K78, K120, K123, K126, K129, K148, K168, K170, K178, K185, K204, K230, K233, K245, K275, K278, K312, K326, K349, K359, K441, K463, K470, K471, K494, K501, K524, K536, K563, K570, K599, K600, and K604 of TOM70; and/or ubiquitination increases at at least one, at least two, at least three, or four amino acids selected from K209, K245, K316, and K326 of MAT2B; and/or ubiquitination increases at at least one, at least two, at least three, at least four, or five amino acids selected from K83, K91, K166, K241, and K253 of PRDX3; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, or six amino acids selected from K558, K657, K854, K884, K929, and K933 of IDE; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, or seven amino acids selected from K20, K53, K61, K109, K110, K266, and K274 of VDAC1; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, or six amino acids selected from K31, K64, K120, K121, K277, and K285 of VDAC2; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, or eight amino acids selected from K20, K53, K61, K109, K110, K163, K266, and K274 of VDAC3; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten amino acids selected from K238, K353, K436, K437, K548, K556, K613, K678, K690, K705, K775, and K806 of IP05; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten amino acids selected from K2, K32, K99, K115, K122, K132, K161, K186, K313, K321, K347, K350, and K361 of PSD13; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten amino acids selected from K18, K190, K259, K326, K328, K401, K405, K414, K418, K435, K586, K587, and K640 of UBP13; and/or ubiquitination increases at at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, or nine amino acids selected from K47, K76, K81, K95, K106, K119, K134, K171, K177 of PTH2. In some embodiments, ubiquitination of one or more additional proteins increases upon contacting a cell with an inhibitor of USP30. Nonlimiting exemplary proteins whose ubiquitination may be increased in the presence of an inhibitor of USP30 are listed in Appendix A, which is incorporated herein by reference. Increased ubiquitination of a target protein can be determined, e.g., by immunoaffinity enrichment of ubiquitinated peptides after trypsin digestion, followed by mass spectrometry, as described in Example 5. In some embodiments, an increase in ubiquitination may be determined by comparing the ubiquitination of a target protein a cell or population of cells contacted with an inhibitor of USP30 with the ubiquitination of the same target protein in a matched cell or population of cells not contacted with the inhibitor.
In some embodiments, increased ubiquitination of a protein means an increase in ubiquitination of the protein in a cell or population of cells contacted with an inhibitor of USP30 of at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 100% (i.e., 2-fold), at least 150%, or at least 200% (i.e., 3-fold) as compared to a matched cell or population of cells not contacted with the inhibitor.
In some embodiments, the cell is under oxidative stress. Further, in some embodiments, a method of reducing oxidative stress in a cell is provided, the method comprising contacting the cell with an inhibitor of USP30 under conditions allowing inhibition of USP30 in the cell.
In any of the foregoing methods, the cell may comprise a pathogenic mutation in Parkin, a pathogenic mutation in PINK1, or a pathogenic mutation in Parkin and a pathogenic mutation in PINK1. Nonlimiting exemplary pathogenic mutations in Parkin and PINK1 are shown, e.g., in Tables 1 and 2 herein.
In some embodiments, the cell is a neuron. In some embodiments, the cell is a substantia nigra neuron. In some embodiments, the cell is a cardiac cell. In some embodiments, the cell is a cardiomyocyte cell. In some embodiments, the cell is a muscle cell.
In some embodiments of any of the foregoing methods, the cell is comprised in a subject. In some embodiments of any of the foregoing methods, the cell may be in vitro or ex vivo.
In another aspect, an inhibitor of USP30 for use as a medicament is provided. In further aspects, an inhibitor of USP30 for use in a method of treatment is provided. In some embodiments, a method of treating a condition involving a mitochondrial defect in a subject is provided, the method comprising administering to the subject an effective amount of an inhibitor of USP30. A condition involving a mitochondrial defect may involve a mitophagy defect, one or more mutations in mitochondrial DNA, mitochondrial oxidative stress, defects in mitochondrial shape/morphology, mitochondrial membrane potential defects, and/or a lysosomal storage defect. Nonlimiting exemplary conditions involving mitochondrial defects include neurodegenerative diseases; mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome; Leber's hereditary optic neuropathy (LHON); neuropathy, ataxia, retinitis pigmentosa-maternally inherited Leigh syndrome (NARP-MILS); Danon disease; ischemic heart disease leading to myocardial infarction; multiple sulfatase deficiency (MSD); mucolipidosis II (ML II); mucolipidosis III (ML III); mucolipidosis IV (ML IV); GM1-gangliosidosis (GM1); neuronal ceroid-lipofuscinoses (NCL1); Alpers disease; Barth syndrome; Beta-oxidation defects; carnitine-acyl-carnitine deficiency; carnitine deficiency; creatine deficiency syndromes; co-enzyme Q10 deficiency; complex I deficiency; complex II deficiency; complex III deficiency; complex IV deficiency; complex V deficiency; COX deficiency; chronic progressive external ophthalmoplegia syndrome (CPEO); CPT I deficiency; CPT II deficiency; glutaric aciduria type II; Kearns-Sayre syndrome; lactic acidosis; long-chain acyl-CoA dehydrongenase deficiency (LCHAD); Leigh disease or syndrome; lethal infantile cardiomyopathy (LIC); Luft disease; glutaric aciduria type II; medium-chain acyl-CoA dehydrongenase deficiency (MCAD); myoclonic epilepsy and ragged-red fiber (MERRF) syndrome; mitochondrial recessive ataxia syndrome; mitochondrial cytopathy; mitochondrial DNA depletion syndrome; myoneurogastointestinal disorder and encephalopathy; Pearson syndrome; pyruvate carboxylase deficiency; pyruvate dehydrogenase deficiency; POLG mutations; medium/short-chain 3-hydroxyacyl-CoA dehydrogenase (M/SCHAD) deficiency; and very long-chain acyl-CoA dehydrongenase (VLCAD) deficiency. Nonlimiting exemplary neurodegenerative diseases that involve mitochondrial defects include Parkinson's disease, Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis (ALS), ischemia, stroke, dementia with Lewy bodies, and frontotemporal dementia. Additional exemplary neurodegenerative diseases that may involve mitochondrial defects include, but are not limited to, intracranial hemorrhage, cerebral hemorrhage, trigeminal neuralgia, glossopharyngeal neuralgia, Bell's Palsy, myasthenia gravis, muscular dystrophy, progressive muscular atrophy, primary lateral sclerosis (PLS), pseudobulbar palsy, progressive bulbar palsy, spinal muscular atrophy, inherited muscular atrophy, invertebrate disk syndromes, cervical spondylosis, plexus disorders, thoracic outlet destruction syndromes, peripheral neuropathies, prophyria, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, demyelinating diseases, Guillain-Barre syndrome, multiple sclerosis, Charcot-Marie-Tooth disease, prion disease, Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker syndrome (GSS), and fatal familial insomnia. In some such embodiments, the method further comprises administering to the individual an effective amount of at least one additional therapeutic agent, e.g., as described below.
In some embodiments, an inhibitor of USP30 is provided for use in the manufacture or preparation of a medicament. In some such embodiments, the medicament is for treatment of conditions involving a mitochondrial defect, such as, for example, conditions involving a mitophagy defect, conditions involving mutations in mitochondrial DNA, conditions involving mitochondrial oxidative stress, conditions involving defects in mitochondrial shape/morphology, conditions involving defects in mitochondrial membrane potential, and conditions involving lysosomal storage defects. In further embodiments, the medicament is for use in a method of treating a condition involving a mitochondrial defect, the method comprising administering to an individual having the condition involving a mitochondrial defect an effective amount of the medicament. In one such embodiment, the method further comprises administering to the individual an effective amount of at least one additional therapeutic agent, e.g., as described below.
An “individual” according to any of the embodiments herein may be a human.
In a further aspect, pharmaceutical formulations comprising any of the inhibitors of USP30 provided herein, e.g., for use in any of the above therapeutic methods are provided. In one embodiment, a pharmaceutical formulation comprises any of the inhibitors of USP30 provided herein and a pharmaceutically acceptable carrier. In another embodiment, a pharmaceutical formulation comprises any of the inhibitors of USP30 provided herein and at least one additional therapeutic agent, e.g., as described below.
Inhibitors of USP30 can be used either alone or in combination with other agents in a therapy. For instance, an inhibitor of USP30 may be co-administered with at least one additional therapeutic agent.
Exemplary therapeutic agents that may be combined with an inhibitor of USP30, e.g., for the treatment of Parkinson's disease, include levodopa, dopamine agonists (such as pramipexole, ropinirole, and apomorphine), monoamine oxygenase (MAO) B inhibitors (such as selegiline and rasagiline), catechol O-methyltransferase (COMT) inhibitors (such as entacapone and tolcapone), anticholinergics (such as benzotropine and trihexylphenidyl), and amantadine. A further exemplary therapeutic agent that may be combined with an inhibitor of USP30, e.g., for the treatment of amyotrophic lateral sclerosis, is riluzole. Exemplary therapeutic agents that may be combined with an inhibitor of USP30, e.g., for the treatment of Alzheimer's disease, include cholinesterase inhibitors (such as donepezil, rivastigmine, galantamine, and tacrine), and memantine. Exemplary therapeutic agents that may be combined with an inhibitor of USP30, e.g., for the treatment of Huntington's disease, include tetrabenazine, antipsychotic drugs (such as haloperidol and clozapine), clonazepam, diazepam, antidepressants (such as escitalopram, fluoxetine, and sertraline), and mood-stabilizing drugs (such as lithium), and anti-convulsants (such as valproic acid, divalproex, and lamotrigine).
Administration “in combination” encompasses combined administration (where two or more therapeutic agents are included in the same or separate formulations), and separate administration, in which case, administration of the inhibitor of the invention can occur prior to, simultaneously, and/or following, administration of the additional therapeutic agent and/or adjuvant. In some embodiments, administration of the inhibitor of USP30 and administration of an additional therapeutic agent occur within about one month, or within about one, two, or three weeks, or within about one, two, three, four, five, or six days of one another Inhibitors of the invention can also be used in combination with other types of therapies.
An inhibitor of the invention (and any additional therapeutic agent) can be administered by any suitable means, including oral, parenteral, intrapulmonary, intranasal, and intralesional administration. Parenteral administration includes, but is not limited to, intramuscular, intravenous, intraarterial, intracerebral, intracerebroventricular, intrathecal, intraocular, intraperitoneal, and subcutaneous administration. An inhibitor of the invention (and any additional therapeutic agent) may also be administered using an implanted delivery device, such as, for example, an intracerebral implant. Nonlimiting exemplary central nervous system delivery methods are reviewed, e.g., in Pathan et al., Recent Patents on Drug Delivery & Formulation, 2009, 3: 71-89. Dosing can be by any suitable route, e.g. by injections, such as intravenous or subcutaneous injections, depending in part on whether the administration is brief or chronic. Various dosing schedules including but not limited to single or multiple administrations over various time-points, bolus administration, and pulse infusion are contemplated herein.
Inhibitors of the invention would be formulated, dosed, and administered in a fashion consistent with good medical practice. Factors for consideration in this context include the particular disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disorder, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to medical practitioners. The inhibitor need not be, but is optionally formulated with one or more agents currently used to prevent or treat the disorder in question. The effective amount of such other agents depends on the amount of inhibitor present in the formulation, the type of disorder or treatment, and other factors discussed above. These are generally used in the same dosages and with administration routes as described herein, or about from 1 to 99% of the dosages described herein, or in any dosage and by any route that is empirically/clinically determined to be appropriate.
For the prevention or treatment of disease, the appropriate dosage of an inhibitor of USP30 (when used alone or in combination with one or more other additional therapeutic agents) will depend on the type of disease to be treated, the type of inhibitor, the severity and course of the disease, whether the inhibitor is administered for preventive or therapeutic purposes, previous therapy, the patient's clinical history and response to the inhibitor, and the discretion of the attending physician. The inhibitor is suitably administered to the patient at one time or over a series of treatments. Depending on the type and severity of the disease, about 1 μg/kg to 15 mg/kg (e.g. 0.1 mg/kg-10 mg/kg) of inhibitor can be an initial candidate dosage for administration to the patient, whether, for example, by one or more separate administrations, or by continuous infusion. One typical daily dosage might range from about 1 μg/kg to 100 mg/kg or more, depending on the factors mentioned above. For repeated administrations over several days or longer, depending on the condition, the treatment would generally be sustained until a desired suppression of disease symptoms occurs. One exemplary dosage of the inhibitor would be in the range from about 0.05 mg/kg to about 10 mg/kg. Thus, one or more doses of about 0.5 mg/kg, 2.0 mg/kg, 4.0 mg/kg or 10 mg/kg (or any combination thereof) may be administered to the patient. Such doses may be administered intermittently, e.g. every week or every three weeks (e.g. such that the patient receives from about two to about twenty, or e.g. about six doses of the inhibitor). An initial higher loading dose, followed by one or more lower doses may be administered. However, other dosage regimens may be useful. The progress of this therapy is easily monitored by conventional techniques and assays.
It is understood that any of the above formulations or therapeutic methods may be carried out using more than one inhibitor of USP30.
E. Articles of Manufacture
In another aspect of the invention, an article of manufacture containing materials useful for the treatment, prevention and/or diagnosis of the disorders described herein is provided. The article of manufacture comprises a container and a label or package insert on or associated with the container. Suitable containers include, for example, bottles, vials, syringes, IV solution bags, etc. The containers may be formed from a variety of materials such as glass or plastic. The container holds a composition which is by itself or combined with another composition effective for treating, preventing and/or diagnosing the disorder and may have a sterile access port (for example the container may be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle). At least one active agent in the composition is an inhibitor of the invention. The label or package insert indicates that the composition is used for treating the condition of choice. Moreover, the article of manufacture may comprise (a) a first container with a composition contained therein, wherein the composition comprises an inhibitor of the invention; and (b) a second container with a composition contained therein, wherein the composition comprises a further cytotoxic or otherwise therapeutic agent. The article of manufacture in this embodiment of the invention may further comprise a package insert indicating that the compositions can be used to treat a particular condition. Alternatively, or additionally, the article of manufacture may further comprise a second (or third) container comprising a pharmaceutically-acceptable buffer, such as bacteriostatic water for injection (BWFI), phosphate-buffered saline, Ringer's solution or dextrose solution. It may further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, and syringes.
The following are examples of methods and compositions of the invention. It is understood that various other embodiments may be practiced, given the general description provided above.
DUB cDNA Overexpression Screen:
To identify regulators of mitophagy, individual cDNAs from a FLAG-tagged DUB library were cotransfected into HeLa cells with GFP-Parkin using Lipofectamine 2000 (Invitrogen) (1:3 DUB-FLAG: GFP-Parkin cDNA ratio). After 24 hours of expression, cells were treated with 10 μM CCCP for 24 hours, and fixed and stained using anti-Tom20 (Santa Cruz Biotechnology), anti-GFP (Ayes Labs) and anti-FLAG (Sigma) primary antibodies. Following staining with secondary antibodies, images of random fields were acquired with a Leica SP5 Laser Scanning Confocal Microscope using a 40×/1.25 oil-objective (0.34 μm/pixel resolution, 1 μm confocal z-step size). Percent of GFP-Parkin and FLAG-DUB cotransfected cells containing Tom20 staining was scored blindly.
Dissociated hippocampal neuron cultures were prepared as described (Seeburg et al., Neuron 58: 571-583 (2008)) and transfected using Lipofectamine LTX PLUS at DIV 8-10. Constructs were expressed for 1-3 days for overexpression experiments and 3-4 days for knockdown experiments. mt-Keima-transfected neurons were imaged with a Leica TCS SP5 Laser Scanning Confocal microscope with a 40×/1.25 oil objective (0.07 μm/pixel resolution, 1 μm confocal z-step size). Cells were kept in a humidified chamber maintained at 37° C./5% CO2 during imaging. Two images were acquired using a hybrid detector in sequential mode with 458 nm (neutral pH signal) and 543 nm (acidic pH signal) laser excitation, and emission fluorescence collected between 630-710 nm. All image quantification was performed by custom-written macros in ImageJ. For mt-Keima quantification, cell bodies were manually outlined and total area of high ratio (543 nm/458 nm) lysosomal signal was divided by the total area of somatic mitochondrial signal (mitophagy index).
To determine Parkin substrates, HEK-293 GFP-Parkin inducible cells were treated with doxycycline for 24 hours, and then treated with 5 μM CCCP or DMSO vehicle control for 2 hours. To determine USP30 substrates, HEK-293T cells were transfected with human USP30 shRNA using Lipofectamine 2000 (Invitrogen) for 6 days, then treated as before. In both experiments, cells were lysed (20 mM HEPES pH 8.0, 8M urea, 1 mM sodium orthovanadate, 2.5 mM sodium pyrophosphate, 1 mM β-glycerophosphate), sonicated, and cleared by centrifugation prior to proteolytic digestion and immunoaffinity enrichment of peptides bearing the ubiquitin remnant, and mass spectrometry analysis.
For total lysate experiments, transfected HEK-293 cells were lysed at 24 hours post-transfection in SDS sample buffer (Invitrogen) containing sample reducing agent (Invitrogen). For immunoprecipitation experiments, cells were lysed at 24 hours (overexpression experiments) or 6 days (knockdown experiments) post-transfection in TBS buffer containing 0.5% SDS, and lysates were diluted with a buffer containing 1% Triton-X-100 and protease and phosphatase inhibitors. Ubiquitinated proteins were immunoprecipated from lysates of HA-ubiquitin transfected cells with anti-HA affinity matrix beads (Roche Applied Science). Inputs and precipitates were resolved by SDS-PAGE and analyzed by immunoblotting.
Error bars indicate standard error of the mean (S.E.M.), To compute p values, non-paired Student's t-test, One-way ANOVA with Dunnett's Multiple Comparison test (for comparisons to a single condition) or Bonferroni's Multiple Comparison test (for comparisons between multiple conditions), and Two-way ANOVA were used, as indicated in figure legends. All statistical analysis was performed in GraphPad Prism v.5 software.
For the DUB overexpression screen, a FLAG-tagged DUB library consisting of 100 cDNAs was used. For transfection, the following constructs were subcloned into β-actin promoter-based pCAGGS plasmid: USP30-FLAG (rat), USP30-FLAG (human), GFP-Parkin (human), FLAG-Parkin (human), PINK1-GFP (human), myc-Parkin (human), RHOT1 (MIRO)-myc-FLAG (human), TOM20-myc (human), HA-ubiquitin, PSD-95-FLAG, and mt-mKeima (Katayama et al., Chemistry & Biology 18: 1042-1094 (2011)). Point mutations were generated using QuikChange II XL (Agilent Technologies) for the following constructs: USP30-C77S-FLAG (rat), USP30-C77A-FLAG (rat), USP30-C77S-FLAG (human), GFP-Parkin K161N (human), and GFP-Parkin G430D (human). Mito-tagGFP2 (Evrogen), Tom20-3KR-myc, and HA-ubiquitin mutants (Blue Heron) were purchased. β-Gal (Seeburg and Sheng, J. Neurosci. 28: 6583-6591 (2008)) and mito-ro-GFP (Dooley et al., J. Biol. Chem. 279: 22284-22293 (2004)) expression plasmids were previously described. Short-hairpin sequences targeting the following regions were cloned into pSuper or pSuper-GFP-neo plasmids: rat PINK1 #1 (TCAGGAGATCCAGGCAATT), rat PINK1 #2 (CCAGTACCTTGAAGAGCAA), rat Parkin #1 (GGAAGTGGTTGCTAAGCGA), rat Parkin #2 (GAGGAAAAGTCACGAAACA), rat USP30 (CCAGAGCCCTGTTCGGTTT), human USP30 (CCAGAGTCCTGTTCGATTT), and firefly luciferase (CGTACGCGGAATACTTCGA).
The following antibodies were used for immunocytochemistry: rabbit anti-TOM20, mouse anti-TOM20, goat anti-HSP60 (Santa Cruz Biotechnology); mouse anti-FLAG, rabbit anti-FLAG, mouse anti-myc (Sigma-Aldrich); and chicken anti-GFP (Ayes Labs).
The following antibodies were used for immunoblotting: rabbit anti-TOM20, goat anti-HSP60 (Santa Cruz Biotechnology); mouse anti-MFN1, HRP-conjugated anti-FLAG, mouse anti-myc, rabbit anti-USP30, rabbit anti-RHOT1 (MIRO), rabbit anti-TIMM8A (Sigma-Aldrich); rabbit anti-GFP, chicken anti-GFP (Invitrogen); HRP-conjugated anti-GAPDH, HRP-conjugated anti-α-actin, HRP-conjugated anti-β-tubulin, rabbit anti-VDAC (Cell Signaling Technology); rabbit anti-TOM70 (Proteintech Group); anti-ubiquitin (FK2) (Enzo Life Sciences); mouse anti-LAMP1 (StressGen); HRP-conjugated anti-HA (Roche); and anti-USP30 rabbit (generated by immunizing rabbits with purified human USP30 amino acids 65-517).
For immunoprecipitation experiments anti-FLAG M2 affinity gel beads (Sigma) and anti-HA affinity matrix beads (Roche Applied Science) were used.
Adeno-associated virus type2 (AAV2) particles expressing Parkin, PINK1 and USP30 shRNAs were produced by Vector Biolabs, Inc. from pAAV-BASIC-CAGeGFP-WPRE vector containing the H1 promoter and shRNA expression cassette of the pSuper vectors.
The following reagents were purchased as indicated: blasticidin S, zeocin, Lipofectamine 2000, Lipofectamine LTX PLUS, LysoTracker Green DND-626 (Invitrogen); PhosSTOP phosphatase inhibitor tablets, cOmplete EDTA-free protease inhibitor tablets, DNase I (Roche Applied Science); carbonyl cyanide 3-chlorophenylhydrazone (CCCP), doxycycline, dimethyl sulfoxide, ammonium chloride, rotenone, DTT, aldrithiol, paraquat dichloride (Sigma-Aldrich); N-Ethylmaleimide (Thermo Scientific); and hygromycin (Clontech Laboratories).
All heterologous cells were transfected with Lipofectamine 2000 for cDNA expression and Lipofectamine RNAiMAX for siRNA knockdown experiments, according to manufacturer's instructions (Invitrogen). siRNAs were purchased from Dharmacon as siGenome pools (non-Silencing pool #2 was used control siRNA transfection). Hippocampal cultures were prepared as described previously (Seeburg et al., Neuron 58: 571-583 (2008)) and transfected with Lipofectamine LTX PLUS (Invitrogen) with 1.8 μg DNA, 1.8 μl PLUS reagent and 6.3 μl LTX reagent. Following drug treatments, cells were fixed with 4% paraformaldehyde/4% sucrose in phosphate-buffered saline (PBS, pH 7.4) (Electron Microscopy Sciences). Following permeabilization (0.1% Triton-X in PBS), blocking (2% BSA in PBS) and primary antibody incubation, antibodies were visualized using Alexa dye-conjugated secondary antibodies (Invitrogen). All immunocytochemistry images were acquired with a Leica SP5 laser scanning microscope with a 40×/1.25 oil objective (0.34 μm/pixel resolution, 1 μm confocal z-step size).
Stably transfected HEK cell lines expressing GFP-Parkin (human) wild-type, K161N, and G430D were generated by co-transfecting FLP-In 293 cells with a pOG44 Flp-recombinase expression vector (Invitrogen) and a pcDNA5-FRT vector (Invitrogen) expressing the corresponding constructs under a CMV promoter. Cell lines were selected and maintained using 50 μg/mL hygromycin selection. Inducible HEK stable cell line expressing GFP-Parkin (human) was generated by co-transfecting FLP-In T-Rex 293 cells with pOG44 and a pcDNA5-FRT-TO vector (Invitrogen) expressing GFP-Parkin (human). The line was selected and maintained using 50 μg/mL hygromycin and 15 μg/mL blasticidin. SH-SY5Y stable cells were generated similarly with a Flp-In inducible parental cell line using pcDNA5-FRT-TO and maintained under 75 μg/ml hygromycin and 3 μg/ml blasticidin.
To identify Parkin substrates, HEK 293T cells stably expressing inducible GFP-Parkin (human) were induced using doxycycline (1 μg/mL) for 24 hours, then treated with 5 μM CCCP or DMSO vehicle control for 2 hours. To determine USP30 substrates, HEK 293T cells were transfected with human USP30 shRNA using Lipofectamine 2000 (Invitrogen) for 6 days, then treated as above.
Immunoaffinity isolation and mass spectrometry methods were used to enrich and identify K-GG peptides from digested protein lysates as previously described (Xu et al., Nat. Biotech., 28: 868-873 (2010); Kim et al., Mol. Cell, 44: 325-340 (2011)). Cell lysates were prepared in lysis buffer (8M urea 20 mM HEPES pH 8.0 with 1 mM sodium orthovanadate, 2.5 mM sodium pyrophosphate, 1 mM B-glycerophosphate) by brief sonication on ice. Protein samples (60 mg) were reduced at 60° C. for 20 min in 4.1 mM DTT, cooled 10 min on ice, and alkylated with 9.1 mM iodoacetamide for 15 min at room temperature in the dark. Samples were diluted 4X using 20 mM HEPES pH 8.0 and digested in 10 μg/ml trypsin overnight at room temperature. Following digestion, TFA was added to a final concentration of 1% to acidify the peptides prior to desalting on a Sep-Pak C18 cartridge (Waters). Peptides were eluted from the cartridge in 40% ACN/0.1% TFA, flash frozen and lyophilized for 48 hr. Dry peptides were gently resuspended in 1.4 ml 1×IAP buffer (Cell Signaling Technology) and cleared by centrifugation for 5 min at 1800×g. Precoupled anti-KGG beads (Cell Signaling Technology) were washed in 1×IAP buffer prior to contacting the digested peptides.
Immunoaffinity enrichment was performed for 2 hours at 4° C. Beads were washed 2X with IAP buffer and 4X with water prior to 2X elution of peptides in 0.15% TFA for 10 min each at room temperature. Immunoaffinity enriched peptides were desalted using STAGE-Tips as previously described (Rappsilber et al., Anal. Chem., 75: 663-670 (2003)).
Liquid chromatography-mass spectrometry (LC-MS) analysis was performed on an LTQ-Orbitrap Velos mass spectrometer operating in data dependent top 15 mode. Peptides were injected onto a 0.1×100-mm Waters 1.7-um BEH-130 C18 column using a NanoAcquity UPLC and separated at 1 ul/min using a two stage linear gradient where solvent B ramped first from 2% to 25% over 85 min and then 25% to 40% over 5 min. Peptides eluting from the column were ionized and introduced to the mass spectrometer using an ADVANCE source (Michrom-Bruker). In each duty cycle, one full MS scan collected was at 60,000 resolution in the Orbitrap followed by up to 15 MS/MS scans in the ion trap on monoisotopic, charge state defined precursors (z>1). Ions selected for MS/MS (+20 ppm) were subjected to dynamic exclusion for 30 sec duration.
Mass spectral data were converted to mzxml for loading into a relational database. MS/MS spectra were searched using Mascot against a concatenated target-decoy database of tryptic peptides from human proteins (Uniprot) and common contaminants. Precursor ion mass tolerance was set to +50 ppm. Fixed modification of carbamidomethyl cysteine (+57.0214) and variable modifications of oxidized methionine (+15.9949) and K-GG (+114.0429) considered. Linear discriminant analysis (LDA) was used to filter peptide spectral matches (PSMs) from each run to 5% false discovery rate (FDR) at the peptide level, and subsequently to a 2% protein level FDR as an aggregate of all runs (<0.5% peptide level FDR). Localization scores were generated for each K-GG PSM using a modified version of the AScore algorithm and positions of the modifications localized accordingly as the AScore sequence. (Beausoleil et al., Nat. Biotech. 24(10): 1285-1292 (2006)). Given work showing that trypsin cannot cut adjacent to ubiquitin modified lysines PSMs where the AScore sequence reports a -GG modification on the C-terminal lysine are dubious (Bustos et al., Mol. Cell. Proteomics, published online Jun. 23, 2012, doi: 10.1074/mcp.R112.019117; Seyfried et al., Anal. Chem., 80: 4161-4169 (2008)). Possible exceptions to this would be lysines at the C-termini of proteins (or in vivo truncation products), PSMs stemming from in source fragmentation of a bona fide K-GG peptide. To establish the most reliable dataset for downstream analysis, PSMs where the AScore sequence reports a C-terminal lysine were split into two groups: those with an available internal lysine residue to which the -GG could be alternatively localized, and those which lacked an available lysine. PSMs bearing a C-terminal K-GG but lacking an available lysine were removed from consideration in downstream analyses. For the remaining PSMs, the -GG modification was relocalized to the available lysine closest to the C-terminus.
Confidently identified peptides with ambiguous localization (AScore<13) bearing only a single internal lysine residue were reported with the modification localized to that internal lysine. Peptides where the modification has been assigned to the C-terminal lysine with an AScore>13 were discarded based on evidence suggesting that trypsin cannot cleave at a ubiquitin modified lysine residue.
A modified version of the VistaGrande algorithm, termed XQuant, was employed to interrogate the unlabeled peak areas for individual K-GG peptides, guided by direct PSMs or accurate precursor ion and retention time matching (cross quantitation). For direct PSMs, quantification of the unlabeled peak area was performed as previously described using fixed mass and retention tolerances (Bakalarski et al., J. Proteome Res., 7: 4756-4765 (2008)). To enable cross quantitation within XQuant, retention time correlation across pairwise instrument analyses was determined based on high-scoring peptide sequences identified by between one and four PSMs across all analyses within an experiment. Matched retention time pairings were modeled using a linear least squares regression model to yield the retention time correlation equation. In instrument analyses where a peptide was not identified by a discrete MS/MS, cross quantification was carried out by seeding the XQuant algorithm with the calculated mass of the precursor ion and its predicted retention time derived from the regression model. While the m/z tolerance was fixed, the retention time tolerance was dynamically adjusted for each pairwise instrument run. In cases where peptides were not confidently identified within a given instrument run but were identified in multiple other runs, multiple cross quantification events were performed to ensure data quality. XQuant results were filtered to a heuristic confidence score of 83 or greater, as previously described (Bakalarski et al., J. Proteome Res., 7: 4756-4765 (2008)). Full scan peak area measurements arising from multiple quantification events of the same m/z within a single run were grouped together if their peak boundaries in retention time overlapped. From such a group, the peak with the largest total peak area was chosen as its single representative.
To identify candidate substrates of Parkin and USP30, graphical analysis and mixed-effect modeling were applied to the XQuant data. A mixed-effect model was fit to the AUC data for each protein. “Treatment” (e.g. Control, Parkin overexpression/USP30 knockdown, CCCP, Combo) was a categorical fixed effect and “Peptide” was fit as random effect. False discovery rates (FDR) are calculated based on the P-values of each treatment vs. Control. Fold-changes and P-values of mean AUC from Combo vs. Control and Combo vs. CCCP were utilized in preparing plots. Mixed-effect model was fit in R by ‘nlme’ (Pinheiro et al., nlme: Linear and Nonlinear Mixed Effects Models. R package version 3, 1-101 (2011)).
For total lysate experiments, cells were lysed after 24 hours in SDS sample buffer (Invitrogen) containing sample reducing agent (Invitrogen) and boiled at 95° C. for 10 minutes. Total lysates were resolved by SDS-PAGE and analyzed by immunoblotting. For immunoprecipitation experiments, cells were treated with 5 μM MG132 and the indicated concentrations and durations of CCCP at 24 hours (overexpression experiments) or 6 days (knockdown experiments) in 0.5% SDS in Tris-Buffered Saline (10 mM TRIS, 150 mM NaCl, pH 8.0) and boiled at 70° C. for 10 minutes. Lysates were diluted in immunoprecipitation buffer (50 mM HEPES, 150 mM NaCl, 10% glycerol, 1% Triton-X, protease inhibitors (Roche Applied Science), phosphatase inhibitors (Roche Applied Science), DNAse I (Roche Applied Science), 2 mM N-Ethylmaleimide (Thermo Scientific), pH 7.4), cleared by centrifugation at 31,000 g for 10 minutes, and incubated overnight with anti-HA affinity matrix beads (Roche Applied Science). Inputs and anti-HA immunoprecipitates were resolved by SDS-PAGE and analyzed by immunoblotting.
Subcellular fractionation was performed using the FOCUS SubCell Kit (G Biosciences) from ˜P60 adult male rat forebrain.
The following Drosophila lines were obtained for analysis: y, w; Actin5C-GAL4/CyO, y+(Bloomington Drosophila Stock Center, 4414), UAS-CG3016RNAi (referred to here as UAS-dUSP30RNAi; NIG-Fly Stock Center, 3016R-2). For USP30 knockdown experiments, Actin5C-GAL4 and UAS-dUSP30RNAi were recombined onto the same chromosome using standard genetic techniques.
Flies were raised on Nutri-Fly “German Food” Formulation (Genesee, 66-115), prepared per manufacturer's instructions. All flies were raised at 25° C. and crossed using standard genetic techniques. All experiments were performed using age-matched male flies.
RNA and subsequent cDNA was obtained from single flies following manufacturer's instructions (Qiagen RNeasy Plus kit, Applied Biosystems High Capacity cDNA Reverse Transcription kit). Quantitative RT-PCR was performed using an Applied Biosystems ViiA7 Real-Time PCR system using TaqMan Assays Dm01796115_g1 and Dm01796116_g1 (Drosophila CG3016 (USP30)), Dm01795269_g1 (Drosophila CG5486 (USP47)), and Dm01840115_s1 (Drosophila CG4603 (YOD1)). Dm02134593_g1 (RpII140) was used as a control.
1-day old adult males were fed a solution containing 5% sucrose only (in water) or 5% sucrose+10 mM paraquat (in water) on saturated Whatman paper. After 48 hours of treatment, 15 flies were collected per condition and homogenized in 100 μL water. Standard curve samples were generated by spiking appropriate amounts of paraquat to homogenates from untreated flies. Then the samples were vortex mixed, 200 μl of acetonitrile containing internal standard (Propranolol) was added. The samples were vortexed again and centrifuged at 10,000×g for 10 min. Supernatants were transferred to a new plate that contained 200 μl of water and analyzed by LC-MS/MS to quantify for concentrations of paraquat. The LC-MS/MS consisted of an Agilent 1100 series HPLC system (Santa Clara, Calif.) and an HTS PAL autosampler from CTC Analytics (Carrboro, N.C.) coupled with a 4000 Q TRAP® MS and TurbolonSpray® ion source from Applied Biosystems (Foster City, Calif.). HPLC separation was performed on a Waters Atlantis dC18 column (3 μm 100×2.1 mm) with a Krud Katcher guard column from Phenomenex. Quantitation was carried out using the multiple reaction monitoring (MRM) with transition 185.1→165.1 for paraquat and 260.2→183.1 for propranolol. The lower and upper limit of the assay is 10 μM and 1000 μM, respectively. The quatitation of the assay employed a calibration curve which was constructed through plotting the analyte/IS peak area ration versus the nominal concentration of paraquat with a weighed 1/x2 linear regression.
Adult male thoraxes were isolated from the remainder of the body, then longitudinally hemi-sectioned and immediately fixed and processed as previously described (Greene et al., Proc. Natl. Acad. Sci. USA, 100: 4078-4083 (2003)).
Climbing assays were performed using the following Drosophila lines: y, w; Actin5C-GAL4/CyO, y+(Actin only); y, w; UAS-CG3016-RNAi/CyO, y+(RNAi only); y, w; UAS-CG3016RNAi Actin5C-GAL4/CyO, y+(USP30 knockdown).
1-day old adult males were fed a solution containing 5% sucrose only (in water) or 5% sucrose+10 mM paraquat (in water) on saturated Whatman paper. After 48 hours of treatment, flies were anesthetized using carbon dioxide and transferred in groups of ten to vials containing only 1% agarose for a 1-hour recovery period from the effects of carbon dioxide. The flies were then transferred into a new glass tube, gently tapped to the bottom and scored for their ability to climb. The number of flies climbing vertically >15 cm in 30 seconds was recorded.
Ten adult 1-day old males per vial were fed a solution containing 5% sucrose only (in water) or 5% sucrose+10 mM paraquat (in water) on saturated Whatman paper. The number of live flies was counted at described intervals.
SH-SY5Y cells transfected with control or USP30 siRNAs are treated with rotenone in normal growth medium (DMEM/F12 and 1× GlutaMax) containing 1% Fetal Bovine Serum. Following 24 hours of incubation, Multi-Tox Fluor assay (Promega) is used to measure cell viability according to manufacturer's instructions. GF-AFC fluorescence is normalized to bis-AAF-R110 fluorescence for each condition and presented as a fraction of control (control RNAi+DMSO).
To identify DUBs that regulate mitochondria clearance, a FLAG-tagged human DUB cDNA library (97 DUBs) was screened in an established mitochondrial degradation assay (Narendra et al., J. Cell Biol., 183: 795-803 (2008)). In this assay, mitochondria depolarization induced by protonophore carbonyl cyanide 3-chlorophenylhydrazone (CCCP, 20 μM, 24 hours) results in marked loss of mitochondria in cultured cells overexpressing Parkin (as measured by staining for mitochondria outer membrane protein marker Tom20). CCCP treatment led to a robust disappearance of Tom20 staining in the great majority of cells transfected with GFP-Parkin (>80% of Parkin-transfected cells lacked Tom20 staining after CCCP—
The ability of USP30 overexpression to prevent CCCP-induced mitophagy was also shown in a different cell line (dopaminergic SH-SY5Y cells) transfected with myc-Parkin (
Since USP30 enzymatic activity was necessary for blocking mitophagy, whether USP30 and Parkin have opposing effects on mitochondria ubiquitination was examined. As reported previously, short-term CCCP treatment (20 μM, 4 hours) caused Parkin redistribution to mitochondria (marked by Tom20) and led to accumulation of ubiquitination signal on mitochondria (measured by staining with polyubiquitin antibody FK2,
Previous studies indicated that Parkin pathogenic mutants defective in ligase activity cannot support mitochondrial degradation in response to CCCP, leading to clustering of uncleared mitochondria in the perinuclear region in association with translocated Parkin (Geisler et al., Nat. Cell Biol., 12: 119-131 (2010); Lee et al., J. Cell Biol., 189: 671-680 (2010)). Remarkably, in cells co-transfected with USP30 plus Parkin and treated with CCCP, wild-type myc-Parkin behaved similarly to mutant Parkin in that it remained associated with the perinuclear clusters of non-degraded mitochondria (
To measure mitophagy in neurons, mt-Keima, a ratiometric pH-sensitive fluorescent protein that is targeted into the mitochondrial matrix, was monitored. A low ratio mt-Keima-derived fluorescence (543 nm/458 nm) reports neutral environment whereas a high ratio fluorescence reports acidic pH (Katayama et al., Chemistry & Biology 18: 1042-1094 (2011)). Thus mt-Keima enables differential imaging of mitochondria in the cytoplasm and mitochondria in acidic lysosomes. Because mt-Keima is resistant to lysosomal proteases, it allows for measurement of cumulative lysosomal delivery of mitochondria over time.
Following transfection in rat dissociated hippocampal cultures, mt-Keima signal accumulated initially in elongated structures characteristic of mitochondria and with low 543/458 ratio values (shown in green—
In heterologous cells, Parkin overexpression can drive mitochondrial degradation upon mitochondria depolarization; however, it is not yet established whether endogenous Parkin and PINK1 are required for mitophagy in non-neural or neural cells (Youle and Narendra, Nat. Rev. Mol. Cell Biol. 12: 9-14 (2011)). To examine the role of the PINK1/Parkin pathway in neuronal mitophagy, Parkin or PINK1 was knocked down using small hairpin RNAs (shRNAs) expressed from pSuper-based vectors. These Parkin and PINK1 shRNAs efficiently knocked down the cDNA-driven expression of their respective targets in heterologous cells (
Next, whether USP30 suppresses mitophagy in neurons as in heterologous cells was investigated. Compared with control neurons transfected with β-Gal and mt-Keima, co-expression of wild-type USP30 caused a ˜60% reduction in mitophagy index at 3 days, indicating that USP30 inhibits lysosomal delivery of mitochondria in neurons (
To test the function of endogenous USP30, USP30 was knocked down using shRNAs. In heterologous cells, rat USP30 shRNA plasmid specifically eliminated the expression of transfected rat USP30 cDNA (
Since Parkin and USP30 antagonistically regulate mitochondrial degradation, it was hypothesized that this E3 ligase and DUB act on some common substrates. To identify Parkin and USP30 substrates, global ubiquitination in cells was analyzed by mass spectrometry (MS) following immunoaffinity enrichment of ubiquitinated peptides from trypsin-digested extracts using the ubiquitin branch-specific (K-GG) antibodies. Global ubiquitination was analyzed and quantified by MS in HEK-293 cells in two different sets of conditions: 1) inducible Parkin overexpression, or 2) USP30 knockdown (USP30 knockdown efficiency was 85±5% (see
We focused additional studies on two mitochondrial proteins—Tom20 and MIRO—that showed large increases in ubiquitination with USP30 knockdown (USP30 shRNA+CCCP/CCCP ubiquitination ratio for Tom20=3.52, p=0.005; for MIRO=2.95, p=0.019; see
It was found that a subset of the shared substrates were regulated by USP30 even under basal conditions (exemplified by Tom20, discussed above). MUL1, ASNS and FKBP8—but not MIRO—were substrates that behaved similarly to Tom20; i.e. they also exhibited a basal increase in ubiquitination with USP30 knockdown in the absence of CCCP. Thus, USP30 basally deubiquitinates this set of proteins, possibly counterbalancing against a mitochondrial E3 ligase that is active in the absence of CCCP and that acts on Tom20 but not MIRO. On the other hand, proteins such as TOM70, MAT2B and PTH2 behaved similarly to MIRO in that they exhibited enhanced ubiquitination with USP30 knockdown only following CCCP, suggesting that USP30 engages in deubiquitination of these proteins only after Parkin is recruited to mitochondria. Parkin, following recruitment to damaged mitochondria, may target both Tom20 and MIRO types of USP30 substrates, shifting the balance towards their polyubiquitination.
Using the same experimental system (cells overexpressing GFP-Parkin and HA-ubiquitin), the function of endogenous USP30 was tested by shRNA suppression. USP30 knockdown did not affect basal ubiquitination of MIRO (in the absence of CCCP-induced mitochondria damage). After mitochondrial depolarization (CCCP 5 μM, 2 hours), however, and consistent with the MS experiments, USP30 knockdown increased the level of ubiquitinated MIRO ˜2.5-fold, as measured in HA-ubiquitin immunoprecipitates (
Parkin has previously been shown to assemble K27-, K48- and K63-type polyubiquitin chains on various mitochondrial substrates (Geisler et al., Nat. Cell Biol., 12: 119-131 (2010)). To examine the polyubiquitin chain topology on Tom20 and Miro, we repeated the ubiquitination assays with HA-ubiquitin mutants where all seven lysine residues were individually replaced with arginine (single K-to-R mutants), or with mutants where a single lysine was left intact and all other six lysines were replaced with arginine. We compared the amount of CCCP-induced Tom20 and Miro ubiquitination afforded by these ubiquitin mutants to wild-type ubiquitin. Among all “single K-to-R mutants”, only the K27R mutation blocked the CCCP-induced ubiquitination of Tom20, whereas the other K-to-R mutants (K6R, K11R, K29R, K33R, K48R, K63R) supported normal Tom20 ubiquitination (
Beyond ubiquitination, does USP30 regulate protein turnover in addition to ubiquitination? Published evidence suggests that Parkin mediates the degradation of multiple mitochondrial outer membrane proteins (Chan et al., Human Mol. Genet., 20: 1726-1737 (2011)). Consistent with this, all of the several outer membrane proteins examined (MIRO, MFN-1, TOM70, VDAC, Tom20) showed significant drop in protein level during the 6 hours of CCCP treatment (5 μM) of GFP-Parkin stable cell lines (
Since MIRO and Tom20 degradation accompanies mitophagy (
MS analysis of ubiquitinated peptides derived from Tom20 identified 3 lysine residues (K56, K61 and K68) whose ubiquitination increased upon CCCP or USP30 knockdown, and that increased even further in response to the combination of CCCP treatment+USP30 knockdown (
In the mt-Keima assay in neurons, overexpression of wild-type Tom20 enhanced mitophagy, whereas the 3KR-Tom20 mutant failed to do so (
Mass spectrometry identified nine lysine-ubiquitination sites on MIRO regulated by USP30 and Parkin, some of which are known to be required for normal MIRO function (e.g. K427 required for GTPase activity (Fransson et al., Bioch. Biophys. Res. Comm., 344: 500-510 (2006)). Thus, instead of a pursuing a combinatorial mutagenesis, the effect of USP30 on MIRO's ability to induce mitophagy was studied since USP30 knockdown increases MIRO ubiquitination (
If mitochondrial degradation defects associated with PD-linked mutations of Parkin are due to impaired ubiquitination of damaged mitochondria, and USP30 indeed functions as a biochemical and functional antagonist of Parkin, then inhibiting USP30 should restore mitochondria ubiquitination and degradation. To test this hypothesis, we focused on PD-linked Parkin pathogenic mutants, such as G430D and K161N, that display attenuated ligase activity (Sriram et al., Human Mol. Genet., 14: 2571-2586 (2005)) with accompanying defects in mitophagy (Geisler et al., Nat. Cell Biol., 12: 119-131 (2010); Lee et al., J. Cell Biol., 189: 671-680 (2010)) were studied (e.g. G430D and K161N).
In SH-SY5Y cells transfected with pathogenic mutant GFP-Parkin-G430D and treated with CCCP, mitochondria fail to be cleared and form perinuclear clusters in association with the defective Parkin protein (
While not intending to be bound by any particular theory, since Parkin ligase activity marks mitochondria through ubiquitination, some residual ligase activity present in Parkin mutants may be needed in order for USP30 knockdown to rescue mitophagy. It is currently unknown whether USP30 knockdown would be effective with complete loss of Parkin activity. It is possible, however that there are other E3s that have overlapping substrates or that can compensate for lack of Parkin.
Since Parkin has broad activity towards outer mitochondrial membrane proteins, we wondered whether Parkin ubiquitinates USP30, which also resides at this mitochondrial compartment. Supporting this possibility, we identified USP30-derived ubiquitinated peptides in proteomics experiments in GFP-Parkin expressing cells treated with CCCP (fold change in ubiquitination of USP30 in ‘GFP-Parkin+CCCP’ over ‘DMSO’=27.23, p<0.001). To confirm USP30 ubiquitination by Parkin, we repeated the ubiquitination assay in cells overexpressing GFP-Parkin and HA-ubiquitin, and found GFP-Parkin induced ubiquitination of endogenous USP30 following CCCP treatment (20 μM, 2 hours,
Whether USP30 knockdown provides functional benefit to mitochondria and cells was examined next. ROS—which largely derive from mitochondria—is associated with neurodegenerative disorders and mitochondria dysfunction may contribute to increased oxidative stress in PD (Lee et al., Biochem. J., 441: 523-540 (2012)). To measure oxidative stress in mitochondria, mitochondria matrix-targeted ro-GFP (mito-roGFP), a redox-sensitive fluorescent protein that allows quantitative ratiometric imaging of mitochondrial redox potential was used (Dooley et al., J. Biol. Chem. 279: 22284-22293 (2004)). Following measurement of ratiometric mito-roGFP signal in individual cells, the dynamic range of the probe was calibrated by treating cultures sequentially with DTT (1 mM) to fully reduce the probe and aldrithiol (100 μM) to fully oxidize the probe (Guzman et al., Nature, 468: 696-700 (2010). Ratios of mito-roGFP measured after DTT and aldrithiol were set to 0 and 1, respectively, to calibrate the relative oxidation index. In control cells transfected with control luciferase shRNA, neurons had a mean relative oxidation index of ˜0.6 (
To test whether knocking down USP30 would provide protection under stress conditions in vivo, we used Drosophila, which has emerged as an effective model system for studying PD molecular pathogenesis (Guo, Cold Spring Harb. Perspect. Med. 2(11) pii: a009944 (2012)). To knock down fly USP30 (CG3016, hereafter called dUSP30), we employed the GAL4/UAS system (Brand et al., Development, 118: 401-415 (1993)). We crossed an Actin-GAL4 driver line with a UAS-dUSP30RNAi transgenic line, which allows expression of dUSP30 RNAi under the control of the Actin promoter (this Actin-GAL4>dUSP30RNAi line is referred to as ‘dUSP30 knockdown’ line). Activation of UAS-dUSP30RNAi by Actin-GAL4 led to a ˜90% reduction of dUSP30 mRNA by quantitative RT-PCR, compared to control parental lines containing only Actin-GAL4 or only UAS-dUSP30RNAi (
To examine the effect of suppressing USP30 in neurons that are relevant to PD, we used dopamine decarboxylase (Ddc)-GAL439 to drive dUSP30RNAi specifically in aminergic neurons of the fly nervous system. As a model of mitochondrial damage and PD, we treated flies with paraquat, a mitochondrial toxin linked to PD (Castello et al., J. Biol. Chem., 282: 14186-14193 (2007); Cocheme et al., J. Biol. Chem., 283: 1786-1798 (2008); Tanner et al., Environmental Health Perspect., 119: 866-872 (2011)). Following treatment with paraquat (10 mM, 48 hours), both the Ddc-GAL4 and UAS-dUSP30RNAi control fly lines showed reduced ability to climb up beyond 15 cm (
To test whether USP30 knockdown has an effect on organism survival, we monitored the percentage of live flies over prolonged treatment with paraquat (10 mM, 96 hours). Flies expressing dUSP30 RNAi survived significantly longer than controls (
Better understanding of the pathogenic mechanisms in PD would be helpful for rational design of disease-modifying therapies for this neurodegenerative disease. Impaired activity of oxidative phosphorylation enzymes (Schapira et al., Lancet, 1: 1269 (1989)), elevated levels of oxidative stress markers (Lee et al., Biochem. J., 441: 523-540 (2012)) and mtDNA mutations (Bender et al., Nature Genet., 38: 515-517 (2006); Kraytsberg et al., Nature Genet., 38: 518-520 (2006)) in PD suggest accumulation of defective mitochondria (Zheng et al., Science Transl. Med., 2: 52ra73 (2010)). PINK1/Parkin genetics further implicate aberrant mitochondrial biology and point to impaired mitochondrial quality control as a causative factor in the etiology of PD (Youle et al., J. Biol. Chem., 12: 9-23 (2011)). Uncleared damaged mitochondria can be a source of toxicity and “pollute” the mitochondrial network through fusion with healthy mitochondria (Tanaka et al., J. Cell. Biol., 191: 1367-1380 (2010)).
We have identified USP30, a DUB localized to mitochondria, as a negative regulator of mitophagy. USP30, through its deubiquitinase activity, opposes Parkin-mediated ubiquitination and degradation of mitochondrial proteins and reverses the marking of damaged mitochondria for mitophagy. Knockdown inhibition of USP30 accelerated mitophagy, and it restored CCCP-induced mitochondrial degradation in cells expressing PD-associated mutants of Parkin. USP30 knockdown improves mitochondrial integrity in parkin mutant flies, confirming that Parkin and USP30 have opposing actions on mitochondrial quality in vivo. USP30 knockdown also conferred motor behavior and survival benefits in wildtype flies treated with paraquat, further supporting the idea that USP30 inhibition might ameliorate the effects of mitochondrial damage.
Although Parkin and PINK1 are identified as key players in mitophagy, a detailed mechanistic understanding of the mitophagy pathway, especially in mammalian cells, is lacking. The fact that basal mitophagy in neurons depends on Parkin and PINK1 (
Since Parkin ligase activity marks mitochondria through ubiquitination, some residual ligase activity present in Parkin mutants is presumably required in order for USP30 knockdown to rescue mitophagy. It would be expected that with complete loss of Parkin activity, USP30 knockdown would be ineffective at rescuing clearance unless other E3 ligases have overlapping substrates and can compensate for lack of Parkin. The rescue of mitochondrial integrity with USP30 knockdown in parkin mutant flies, even though a large portion of parkin gene is missing, supports the latter possibility.
As part of normal turnover, the cleared mitochondria presumably need to be replaced through mitochondrial biogenesis. In culture cell lines, mitochondrial damage increases overall mitochondrial mass (Narendra et al., PLoS Biology, 8: e1000298 (2010)). In this context it is interesting to note that Parkin can also boost mitochondrial biogenesis by degrading negative transcriptional regulators (Shin et al., Cell 144: 689-702 (2011)). Further studies are required to determine whether USP30 also regulates the biogenesis pathway and whether mitophagy induced by USP30 inhibition is accompanied by new mitochondria production.
Global ubiquitination site mapping experiments identified multiple substrates whose ubiquitination is affected by both Parkin overexpression and USP30 knockdown. Amongst these shared presumptive substrates, we confirmed that Miro and Tom20 have ubiquitination levels that are antagonistically regulated by Parkin and USP30, i.e. GFP-Parkin overexpression or USP30 knockdown increased ubiquitination induced by CCCP treatment. Interestingly, a subset of these shared substrates, exemplified by Tom20, was regulated by USP30 even under basal conditions. Mull, Asns and Fkbp8—but not Miro—were mitochondrial substrates that behaved similarly to Tom20, exhibiting a basal increase in ubiquitination with USP30 knockdown in the absence of CCCP. Thus, USP30 basally deubiquitinates this set of proteins, presumably by counterbalancing against a mitochondrial E3 ligase that is active in the absence of CCCP and that acts on Tom20 but not Miro. Following CCCP, USP30 also counteracts Parkin dependent ubiquitination of this set of substrates. On the other hand, proteins such as Tom70, Mat2b and Pth2, behaved similarly to Miro in that they exhibited enhanced ubiquitination with USP30 knockdown only following CCCP. This observation suggests that these set of proteins undergo low levels of basal ubiquitination in the absence of recruited Parkin (i.e. Parkin is their major E3 ligase), or that USP30 is inactive toward those proteins under basal conditions. Mitochondrial depolarization regulates Parkin's E3 ligase activity (Matsuda et al., J. Cell Biol., 189: 211-221 (2010)) possibly via PINK1-mediated phosphorylation (Kondapalli et al., Open Biology, 2: 120080 (2012); but see Vives-Bauza et al., Proc. Natl. Acad. Sci. USA, 107: 378-383 (2010)); it remains to be studied whether the activity of USP30—which is constitutively localized on mitochondria—is also regulated by mitochondrial damage.
Global ubiquitination analysis also revealed a series of non-mitochondrial proteins whose ubiquitination was inversely regulated by Parkin and USP30 (including nuclear proteins, metabolic enzymes and components of the ubiquitin-proteasome system (UPS)). This suggests that the antagonistic functional relationship between Parkin and USP30 may extend beyond mitochondria. These non-mitochondrial “substrates” may be indirectly regulated by Parkin and USP30, or may have subpopulations on mitochondria, but have not formally been assigned as having mitochondrial localization due to the strict filtering criteria employed by computational tools (Pagliarini et al., Cell, 134: 112-123 (2008)). MS also identified some proteins that showed enhanced ubiquitination with CCCP (under endogenous Parkin and USP30 levels) with no further increase in ubiquitination upon Parkin overexpression or USP30 knockdown (e.g. Ssbp, ZO1, Rab10, Vamp1), suggesting engagement of alternative UPS pathways following mitochondrial depolarization. It is appropriate to note that in some cases, elevated levels of ubiquitinated species can derive from increases in the level of the total protein substrate itself.
Interestingly, Parkin also ubiquitinates and degrades USP30, and pathogenic Parkin mutations blocked this ability to downregulate USP30. Failure to remove a negative regulator of mitophagy may exacerbate the inefficient ubiquitination associated with these Parkin mutants, and could also partly explain the rescue of mitophagy by USP30 knockdown.
PD-linked mutations in Parkin may lead to decreased catalytic activity, enhanced aggregation and/or reduced expression (Hampe et al., Human Mol. Genet., 15: 2059-2075 (2006); Matsuda et al., J. Biol. Chem., 281: 3204-3209 (2006); Wang et al., J. Neurochem., 93: 422-431 (2005); Winklhofer et al., J. Biol. Chem. 278: 47199-47208 (2003)). In sporadic PD, Parkin activity can be also inhibited due to cellular stress (Corti et al., Physiol. Rev., 91: 1161-1218 (2011)). PD-linked PINK1 mutations impair translocation of Parkin to damaged mitochondria (Matsuda et al., J. Cell Biol., 189: 211-221 (2010); Narendra et al., PLoS Biology, 8: e1000298 (2010); Vives-Bauza et al., Proc. Natl. Acad. Sci. USA, 107: 378-383 (2010)). Thus, reduced function of Parkin in mitochondrial quality control is likely more prevalent in PD than as represented by rare Parkin mutations, providing further support for a possible utility of USP30 inhibition in idiopathic PD. Consistent with a benefit of USP30 inhibition, knockdown of USP30 restores mitophagy in cells expressing PD-associated mutant Parkin and reduces oxidative stress in neurons. In Drosophila parkin mutants, knockdown of USP30 improves mitochondrial integrity. Furthermore, USP30 knockdown provides a benefit in behavior and survival assays against paraquat, an oxidative stressor linked to mitochondria (Castello et al., J. Biol. Chem., 282: 14186-14193 (2007); Cocheme et al., J. Biol. Chem., 283: 1786-1798 (2008)). Since paraquat is a mitochondrial poison epidemiologically linked to PD (Tanner et al., Environmental Health Perspect., 119: 866-872 (2011)), our findings provide in vivo evidence that inhibition of USP30 might be helpful in diseases caused by mitochondrial damage and dysfunction.
In PD, mitochondrial dysfunction is not specific to substantia nigra neurons and is present systemically (Schapira et al, Parkinson's Dis., 2011: 159160 (2011)). Since USP30 expression seems to be widespread (Nakamura and Hirose, Mol. Biol. Cell, 19: 1903-1914 (2008)), USP30 inhibition has the potential to provide wide benefit by promoting clearance of damaged mitochondria. In addition to neurons, long-lived metabolically active cells such as cardiomyocytes also rely on an efficient mitochondrial quality control system (Gottlieb et al., Am. J. Physiol. Cell Physiol., 299: C203-210 (2010)). In this context, Parkin has been shown to protect cardiac myocytes against ischemia/reperfusion injury through activating mitophagy and clearing damaged mitochondria in response to ischemic stress (Huang et al., PLoS One, 6: e20975 (2011)). In inherited mitochondrial diseases, mtDNA mutations co-exist with wildtype mtDNA within the same cells, and mitochondrial dysfunction and disease ensue only when the proportion of mutated mtDNAs is high (Bayona-Bafaluy et al., Proc. Natl. Acad. Sci. USA, 102: 14392-14397 (2005)). Interestingly, Parkin overexpression eliminates mitochondria with deleterious mtDNA mutations and restores mitochondrial function, presumably by degrading mitochondria containing mutant mtDNA (Suen et al., Proc. Natl. Acad. Sci. USA, 107: 11835-11840 (2010)). Thus, USP30 inhibition has the potential to benefit diseases beyond PD by enhancing mitochondrial quality.
Two types of phage-displayed naïve peptide libraries, Linear-lib and Cyclic-lib, were cycled through rounds of binding selections with biotinylated USP30_cd (USP30 catalytic domain with C77A mutation) in solution as described previously (Stanger, et al., 2012, Nat. Chem. Bio., 7: 655-660). The selection identified peptide USP30—3 and USP30—8, which had moderate spot ELISA signals (signal/noise ratios of ˜5). USP—30 and USP—8 have the sequences:
USP30—3 and USP30—8 were then assayed for inhibition of USP30 and also inhibition of USP7, USP5, UCHL3, and USP2, to determine each peptide's specificity for USP30, as follows. USP30 peptide ligands at a concentration range of 0-100 μM (for USP30—3) and 0-500 μM (for USP30—8) were mixed with 250 nM ubiquitin-AMC (Boston Biochem., Boston, Mass.; Cat. No. U-550). A panel of DUBs at 5.6, 2, 2, 5 and 0.05 nM for USP30, USP7, USP2, USP5, and UCHL3, respectively, in PBS buffer containing 0.05% Tween20, 0.1% BSA and 1 mM DTT for 30 minutes were added to the ubiquitin-AMC/USP30 peptide ligands mixture and the initial velocity was immediately measured by monitoring fluorescence (excitation at 340 nm and emission at 465 nm) using SpectraMax®M5e (Molecular Device, Sunnyvale, Calif.). The initial rates were calculated based on slopes of increasing fluorescence signal. The velocity was normalized to the percentage of the rate when the peptide ligand concentration was zero, and the data was processed using KaleidaGraph by fitting to the following equation:
in which v is the percentage of maximum rate; I is the concentration of inhibitor (USP30 peptide ligands); v0 and vmax are minimum and maximum percentage of the rate, respectively.
The results of that experiment are shown in
Peptide USP30—3 was selected for affinity maturation. To improve the affinity, a soft randomized library was constructed using the USP30—3 sequence as the targeted parent, and panned against USP30_cd in solution as described previously (Stanger, et al., 2012, Nat. Chem. Bio., 7: 655-660). After four rounds of solution panning, 20 peptides were identified that bound to USP30 catalytic domain with stronger spot phage ELISA signal than the parent USP30—3, manifested by an improvement in the signal/noise ratio of about 3-6 fold.
Certain peptides were then tested for specificity for USP30 versus other deubiquitinating enzymes. Binding was tested by ELISA.
Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, the descriptions and examples should not be construed as limiting the scope of the invention. The disclosures of all patent and scientific literature cited herein are expressly incorporated in their entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61809927 | Apr 2013 | US | |
| 61701963 | Sep 2012 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2013/006898 | Sep 2013 | US |
| Child | 14659204 | US |
