Patent Application
20210260002
The present disclosure relates to methods for restoring glial cell potassium (K+) uptake in glial cells having impaired K+ uptake. These methods are suitable for treating a subject suffering from a neuropsychiatric condition.
Schizophrenia is a psychiatric disorder characterized by delusional thought, auditory hallucination and cognitive impairment, which affects roughly 1% of the population worldwide, and yet remains poorly understood (Allen et al., “Systematic Meta-Analyses and Field Synopsis of Genetic Association Studies in Schizophrenia: The SzGene Database,” Nature Genetics 40:827-834 (2008); Sawa & Snyder, “Schizophrenia: Diverse Approaches to a Complex Disease,” Science 296:692-695 (2002)). Over the past decade, it has become clear that a number of schizophrenia-associated genes are involved in the development and physiology of glial cells (Yin et al., “Synaptic Dysfunction in Schizophrenia,” Adv. Exp. Med. Biol. 970:493-516 (2012)). Accordingly, both astrocytic and oligodendrocytic dysfunction has been implicated in the etiology of schizophrenia. Astrocytes in particular have essential roles in both the structural development of neural networks as well as the coordination of neural circuit activity, the latter through their release of glial transmitters, maintenance of synaptic density, and regulation of synaptic potassium and neurotransmitter levels (Christopherson et al., “Thrombospondins are Astrocyte-Secreted Proteins That Promote CNS Synaptogenesis,” Cell 120: 421-433 (2005); Chung et al., “Astrocytes Mediate Synapse Elimination Through MEGF10 and MERTK Pathways,” Nature 504:394-400 (2013); and Thrane et al., “Ammonia Triggers Neuronal Disinhibition and Seizures by Impairing Astrocyte Potassium Buffering,” Nat. Med. 19:1643-1648 (2013)). However, the role that astrocyte dysfunction plays in the development of neuropsychiatric disorders, such as schizophrenia, is unknown. The present disclosure is aimed at overcoming this and other deficiencies in the art.
A first aspect of the present disclosure relates to a method of restoring K+ uptake by glial cells, where said glial cells have impaired K+ uptake. This method involves administering, to the glial cells having impaired K+ uptake, a RE1-Silencing Transcription factor (REST) inhibitor under conditions effective to restore K+ uptake by said glial cells.
Another aspect of the present disclosure relates to a method of restoring K+ uptake by glial cells in a subject. This method involves selecting a subject having impaired glial cell K+ uptake, and administering, to the selected subject, a RE1-Silencing Transcription factor (REST) inhibitor under conditions effective to restore K+ uptake by said glial cells.
Another aspect of the present disclosure relates to a method of treating or inhibiting the onset of a neuropsychiatric disorder in a subject. This method involves selecting a subject having or at risk of having a neuropsychiatric disorder, and administering, to the selected subject, a REST inhibitor under conditions effective to treat or inhibit the onset of the neuropsychiatric disorder in the subject.
To investigate the role of glial pathology in neurological and neuropsychiatric disorders like schizophrenia, a protocol for generating glial progenitor cells (GPCs) from induced pluripotent cells (iPSCs) was established (Wang et al., “Human iPSC-Derived Oligodendrocyte Progenitor Cells Can Myelinate and Rescue a Mouse Model of Congenital Hypomyelination,” Cell Stem Cell 12:252-264 (2013), which is hereby incorporated by reference in its entirety). This model permits the generation of GPCs and their derived astrocytes and oligodendrocytes from patients with schizophrenia, in a manner that preserves their genetic integrity and functional repertoires. This protocol has provided a means by which to assess the differentiation, gene expression and physiological function of astrocytes derived from patients with schizophrenia, both in vitro and in vivo after engraftment into immune deficient mice (Windrem et al., “Human iPSC Glial Mouse Chimeras Reveal Glial Contributions to Schizophrenia,” Cell Stem Cell 21:195-208.e6 (2017), which is hereby incorporated by reference in its entirety). It was noted that such human glial chimeric mice, colonized with iPSC-derived GPCs generated from schizophrenic patients, exhibited profound abnormalities in both astrocytic differentiation and mature structure that were associated with significant physiological and behavioral abnormalities. Importantly, RNA sequence analysis revealed that the developmental defects in these schizophrenia GPCs were associated with the down-regulation of a core set of differentiation-associated genes, whose transcriptional targets included a host of transporters, channels and synaptic modulators found similarly deficient in schizophrenia glia.
As described herein, targetable signaling nodes at which such schizophrenia-associated glial pathology might be moderated were identified. To that end, iPSC GPCs were generated from patients with childhood-onset schizophrenia or from their normal controls (CTR), and astrocytes were produced from these. Both patterns of gene expression and astrocytic functional differentiation by schizophrenic- and control-derived GPCs were compared. Since the preservation of K+ homeostasis is a critical element of astrocytic functional competence, and the RNA-seq data indicated the down-regulation of a number of potassium channels, the uptake of K+ by schizophrenic astrocytes was also assessed. It was found that the schizophrenic cells indeed manifested impaired K+ uptake. Investigating the basis for the impaired transcription of K+ channels by these schizophrenic glia, it was discovered that aberrant expression of the REST repressor is responsible for the diminished potassium channel gene expression and impaired K+ uptake of these schizophrenic astrocytes. By focusing on the development of glial pathology in schizophrenia, the dysregulation of REST dependent transcription has been identified as critical to disease pathogenesis, and as viable target for the treatment of this devastating disorder.
A first aspect of the present disclosure relates to a method of restoring K+ uptake by glial cells, where said glial cells have impaired K+ uptake. This method involves administering, to glial cells having impaired K+ uptake, a RE1-Silencing Transcription factor (REST) inhibitor under conditions effective to restore K+ uptake by said glial cells.
Another aspect of the present disclosure relates to a method of restoring K+ uptake by glial cells in a subject. This method involves selecting a subject having impaired glial cell K+ uptake, and administering, to the selected subject, a RE1-Silencing Transcription factor (REST) inhibitor under conditions effective to restore K+ uptake by said glial cells. In some embodiment, the REST inhibitor is a glial cell targeted REST inhibitor as described herein.
As referred to herein, “glial cells” encompass glial progenitor cells, oligodendrocyte-biased progenitor cells, astrocyte-biased progenitor cells, oligodendrocytes, and astrocytes. Glial progenitor cells are bipotential progenitor cells of the brain that are capable of differentiating into both oligodendrocytes and astrocytes. Glial progenitor cells can be identified by their expression of certain stage-specific surface antigens, such as the ganglioside recognized by the A2B5 antibody and PDGFRα(CD140a), as well as stage-specific transcription factors, such as OLIG2, NKX2.2, and SOX10. Oligodendrocyte-biased and astrocyte-biased progenitor cells are identified by their acquired expression of stage selective surface antigens, including, for example CD9 and the lipid sulfatide recognized by the 04 antibody for oligodendrocyte-biased progenitor cells, and CD44 for astrocyte-biased progenitors. Mature oligodendrocytes are identified by their expression of myelin basic protein, and mature astrocytes are most commonly identified by their expression of glial fibrillary acidic protein (GFAP). In one embodiment of the methods described herein, K+ uptake is restored in glial progenitor cells. In another embodiment, K+ uptake is restored in astrocyte-biased progenitor cells. In another embodiment, K+ uptake is restored in astrocytes.
In accordance with these aspects of the present disclosure, cells having impaired K+ uptake, are glial cells, in particular glial progenitor cells, astrocyte-biased progenitor cells, and astrocytes, having reduced K+ uptake as compared to normal, healthy glial cells. In one embodiment, glial cells having reduced K+ uptake are glial cells where one or more potassium channel encoding genes is down regulated, causing a reduction in the corresponding potassium channel protein expression. In particular, a down regulation in expression of one or more potassium channel encoding genes selected from KCNJ9, KCNH8, KCNA3, KCNK9, KCNC1, KCNC3, KCNB1, KCNF1, KCNA6, SCN3A, SCN2A, SCNN1D, SCN8A, SCN3B, SLC12A6, SLC6A1, SLC8A3, ATP1A2, ATP1A3, ATP2B2 can lead to a reduction in glial cell K+ uptake. As described herein, the down regulation of the aforementioned genes is caused by an upregulation in the expression and activity of the neuron restrictive silencing factor (NRSF), which is also known as RE1-Silencing Transcription Factor (REST). REST is a potent transcriptional repressor, typically involved in the repression of neural genes in non-neural cells.
Thus, in one embodiment, selecting a subject having impaired glial cell K+ uptake involves assessing potassium uptake by glial cells of the subject, comparing the level of potassium uptake by said glial cells to the level of potassium uptake by a population of control, healthy glial cells, and selecting the subject having a reduction in glial cell K+ uptake. In another embodiment, selecting a subject having impaired glial cell K+ uptake involves assessing glial cell expression level of one or more potassium channel encoding genes selected from the group consisting of KCNJ9, KCNH8, KCNA3, KCNK9, KCNC1, KCNC3, KCNB1, KCNF1, KCNA6, SCN3A, SCN2A, SCNN1D, SCN8A, SCN3B, SLC12A6, SLC6A1, SLC8A3, ATP1A2, ATP1A3, ATP2B2, and selecting the subject if there is a downregulation in the expression of the one or more potassium channel encoding genes. In another embodiment, selecting a subject having impaired glial cell K+ uptake involves assessing glial cell protein expression of one or more potassium channels including, GIRK-3 (encoded by KCNJ9), potassium voltage-gated channel subfamily H member 8 (encoded by KCNH8), potassium voltage-gated channel subfamily A member 3 (encoded by KCNA3), potassium channel subfamily K member 9 (encoded by KCNK9), potassium voltage-gated channel subfamily C member 1 (encoded by KCNC1), potassium voltage-gated channel subfamily C member 3 (encoded by KCNC3), potassium voltage-gated channel subfamily B member 1 (encoded by KCNB1), potassium voltage-gated channel subfamily F member 1 (encoded by KCNF1), potassium voltage-gated channel subfamily A member 6 (encoded by KCNA6), Sodium channel protein type 3 subunit alpha (encoded by SCN3A), sodium channel protein type 2 subunit alpha (encoded by SCN2A), amiloride-sensitive sodium channel subunit delta (encoded by SCNN1D), sodium channel protein type 8 subunit alpha (encoded by SCN8A), sodium channel subunit beta-3 (encoded by SCN3B), solute carrier family 12 member 6 (i.e., K+/Cl− cotransporter 3) (encoded by SLC12A6), sodium- and chloride-dependent GABA transporter 1 (i.e., GAT-1) (encoded by SLC6A1), Na+/Ca+2exchanger 3 (encoded by SLC8A3), Na+/K+-transporting ATPase subunit alpha-2 (encoded by ATP1A2), Na+/K+-transporting ATPase subunit alpha-2 (encoded by ATP1A3), plasma membrane calcium-transporting ATPase 2 (i.e., PMCA2) (encoded by ATP2B2). The subject is selected for treatment using the methods as described herein if there is a decrease in the level of one or more potassium channel proteins. In another embodiment, selecting a subject having impaired glial K+ uptake involves assessing glial cell REST expression and selecting the subject if there is an increase in REST gene and/or protein expression.
Potassium uptake, potassium channel gene expression, potassium channel protein expression, and REST gene expression can each be assessed using methods described herein and that are well known to those of skill in the art. These parameters can be assessed in a glial cell sample taken from a subject. Alternatively, one or more of these parameters can be assessed in a glial cell sample derived from induced pluripotent stem cells (iPSCs) derived from the subject. iPSCs can be obtained from virtually any somatic cell of the subject, including, for example, and without limitation, fibroblasts, such as dermal fibroblasts obtained by a skin sample or biopsy, synoviocytes from synovial tissue, keratinocytes, mature B cells, mature T cells, pancreatic β cells, melanocytes, hepatocytes, foreskin cells, cheek cells, or lung fibroblasts, peripheral blood cells, bone marrow cells, etc. iPSCs may be derived by methods known in the art including the use of integrating viral vectors (e.g., lentiviral vectors, inducible lentiviral vectors, and retroviral vectors), excisable vectors (e.g., transposon and foxed lentiviral vectors), and non-integrating vectors (e.g., adenoviral and plasmid vectors) to deliver the aforementioned genes that promote cell reprogramming (see e.g., Takahashi and Yamanaka, Cell 126:663-676 (2006); Okita. et al., Nature 448:313-317 (2007); Nakagawa et al., Nat. Biotechnol. 26:101-106 (2007); Takahashi et al., Cell 131:1-12 (2007); Meissner et al. Nat. Biotech. 25:1177-1181 (2007); Yu et al. Science 318:1917-1920 (2007); Park et al. Nature 451:141-146 (2008); and U.S. Patent Application Publication No. 2008/0233610, which are hereby incorporated by reference in their entirety). Other methods for generating IPS cells include those disclosed in WO2007/069666, WO2009/006930, WO2009/006997, WO2009/007852, WO2008/118820, U.S. Patent Application Publication Nos. 2011/0200568 to Ikeda et al., 2010/0156778 to Egusa et al., 2012/0276070 to Musick, and 2012/0276636 to Nakagawa, Shi et al., Cell Stem Cell 3(5): 568-574 (2008), Kim et al., Nature 454: 646-650 (2008), Kim et al., Cell 136(3):411-419 (2009), Huangfu et al., Nature Biotechnology 26: 1269-1275 (2008), Zhao et al., Cell Stem Cell 3: 475-479 (2008), Feng et al., Nature Cell Biology 11: 197-203 (2009), and Hanna et al., Cell 133(2): 250-264 (2008), which are hereby incorporated by reference in their entirety. Methods of driving the iPSCs toward a glial progenitor cell (GPC) fate and on to an astrocyte fate are described herein and known in the art, see e.g., Wang et al., “Human iPSC-Derived Oligodendrocyte Progenitor Cells can Myelinate and Rescue a Mouse Model of Congenital Hypomyelination,” Cell Stem Cell 12:252-264 (2013), which is hereby incorporated by reference in its entirety.
In another embodiment, glial cells having impaired K+ uptake are glial cells of a subject having a neuropsychiatric disorder. A “neuropsychiatric disorder” as referred to herein, includes any brain disorder with psychiatric symptoms including, but not limited to, dementia, amnesic syndrome, and personality-behavioral changes. Exemplary neuropsychiatric disorders involving impaired K+ channel function and impaired K+ uptake in glial cells that are suitable for treatment using the methods described herein include, without limitation, schizophrenia, autism spectrum disorders, and bipolar disorder.
Thus, another aspect of the present disclosure relates to a method of treating or inhibiting the onset of a neuropsychiatric disorder in a subject. This method involves selecting a subject having or at risk of having a neuropsychiatric disorder, and administering, to the selected subject, a inhibitor under conditions effective to treat or inhibit the onset of the neuropsychiatric disorder in the subject. In some embodiments, the REST inhibitor is a glial cell targeted REST inhibitor.
In one embodiment, the methods described herein are utilized to treat a subject having schizophrenia. Schizophrenia is a chronic and severe mental disorder that affects how an individual thinks, feels, and behaves. To date, there have been several suggested staging models of the disorder (Agius et al., “The Staging Model in Schizophrenia, and its Clinical Implications,” Psychiatr. Danub. 22(2):211-220 (2010); McGorry et al., “Clinical Staging: a Heuristic Model and Practical Strategy for New Research and Better Health and Social Outcomes for Psychotic and Related Disorders,” Can. J Psychiatry 55(8):486-497 (2010); Fava and Kellner, “Staging: a Neglected Dimension in Psychiatric Classification,” Acta Psychiatr. Scand. 87:225-230 (1993), which are hereby incorporated by reference in their entirety). However, generally, schizophrenia develops in at least three stages: the prodromal phase, the first episode, and the chronic phase. There is also heterogeneity of individuals at all stages of the disorder, with some individuals considered ultra-high risk, clinical-high risk, or at-risk for the onset of psychosis (Fusar-Poli et al., “The Psychosis High-Risk State: a Comprehensive State-of-the-Art Review,” JAMA Psychiatry 70:107-120 (2013), which is hereby incorporated by reference in its entirety).
The methods described herein are suitable for treating a subject in any stage of schizophrenia, and at any risk level of psychosis, as all stages will involve impaired glial cell K+ uptake. For example, in one embodiment, a subject treated in accordance with the methods described herein is a subject that is at risk for developing schizophrenia. Such a subject may have one or more genetic mutations in one or more genes selected from ABCA13, ATK1, C4A, COMT, DGCR2, DGCR8, DRD2, MIR137, NOS1AP, NRXN1, OLIG2, RTN4R, SYN2, TOP3B YWHAE, ZDHHC8, or chromosome 22 (22q11) that have been associated with the development of schizophrenia and may or may not be exhibiting any symptoms of the disease. In another embodiment, the subject may be in the prodromal phase of the disease and exhibiting one or more early symptoms of schizophrenia, such as anxiety, depression, sleep disorders, and/or brief intermittent psychotic syndrome. In another embodiment, the subject being treated in accordance with the methods described herein is experiencing psychotic symptoms, e.g., hallucinations, paranoid delusions, of schizophrenia.
In another embodiment, the methods describe herein are utilized to treat a subject having autism or a related disorder. Related disorders include, without limitation, Asperger's disorder, Pervasive Developmental Disorder-Not Otherwise Specified, Childhood Disintegrative Disorder, and Rett's Disorder, which vary in the severity of symptoms including difficulties in social interaction, communication, and unusual behaviors (McPartland et al., “Autism and Related Disorders,” Handb Clin Neurol 106:407-418 (2012), which is hereby incorporated by reference in its entirety). The methods described herein are suitable for the treatment of each one of these conditions and at any stage of the condition. In one embodiment, the subject being treated in accordance with the methods described herein does not exhibit any symptoms of autism or a related condition. In another embodiment, the subject being treated exhibits one or more early symptoms of autism or a related condition. In yet another embodiment, the subject being treated in accordance with the methods described herein exhibits a multitude of symptoms of autism or a related condition.
In another embodiment, the methods describe herein are utilized to treat a subject having bipolar disorder. Bipolar disorder is a group of conditions characterized by chronic instability of mood, circadian rhythm disturbances, and fluctuations in energy level, emotion, sleep, and views of self and others. Bipolar disorders include, without limitation, bipolar disorder type I, bipolar disorder type II, cyclothymic disorder, and bipolar disorder not otherwise specified.
Generally, bipolar disorders are progressive conditions which develop in at least three stages: the prodromal phase, the symptomatic phase, and the residual phase (Kapczinski et al., “Clinical Implications of a Staging Model for Bipolar Disorders,” Expert Rev Neurother 9:957-966 (2009), and McNamara et al., “Preventative Strategies for Early-Onset Bipolar Disorder: Towards a Clinical Staging Model,” CNS Drugs 24:983-996 (2010); which are hereby incorporated by reference in their entirety). The methods described herein are suitable for treating subjects having any of the aforementioned bipolar disorders and subjects in any stage of a particular bipolar disorder. For example, in one embodiment, the subject treated in accordance with the methods described herein is a subject at the early prodromal phase exhibiting symptoms of mood lability/swings, depression, racing thoughts, anger, irritability, physical agitation, and anxiety. In another embodiment, the subject treated in accordance with the methods described herein is a subject at the symptomatic phase or the residual phase.
As used herein, the term “subject” and “patient” expressly includes human and non-human mammalian subjects. The term “non-human mammal” as used herein extends to, but is not restricted to, household pets and domesticated animals. Non-limiting examples of such animals include primates, cattle, sheep, ferrets, mice, rats, swine, camels, horses, poultry, fish, rabbits, goats, dogs and cats.
In accordance with the present disclosure, an inhibitor of REST is administered to glial cells having impaired K+ uptake, which may be the result of impaired channel expression and/or function. In another embodiment, a REST inhibitor is administered to a subject having impaired glial cell K+ uptake. REST is a Kruppel-type zinc finger transcription factor that represses target gene activity upon binding to a 21-nucleotide DNA sequence called repressor element-1 (RE1) that is located in the target gene. REST is the key component of a nuclear complex that includes the other core factors of SIN3A, SIN3B, and RCOR1, and epigenetic regulators such as histone deacetylases (HDACs), histone methyltransferase (EHMT2), and histone-demethylase (KDM1A).
At least four isoforms of human REST exist as a result of alternative splicing. The amino acid sequence of human REST isoform 1 (UniProt identifier Q13127-1) is provided below as SEQ ID NO:1 below.
The nucleotide sequence encoding human REST isoform-1 is provided below as SEQ ID NO: 2 (NCBI Reference Sequence identifier NM_005612.4).
In one embodiment, a suitable REST inhibitor is any agent or compound capable of decreasing the level of REST expression in a glial cell relative to the level of REST expression occurring in the absence of the agent. In one embodiment, therapeutic agents that are suitable for inhibiting or decreasing the level of REST expression in glial cells include, without limitation inhibitory nucleic acid molecules such as a REST antisense oligonucleotide, a REST shRNA, a REST siRNA, and a REST RNA aptamer.
The use of antisense methods to inhibit the in vivo translation of genes and subsequent protein expression is well known in the art (e.g., U.S. Pat. No. 7,425,544 to Dobie et al.; U.S. Pat. No. 7,307,069 to Karras et al.; U.S. Pat. No. 7,288,530 to Bennett et al.; U.S. Pat. No. 7,179,796 to Cowsert et al., which are hereby incorporated by reference in their entirety). In accordance with the present disclosure, suitable antisense nucleic acids are nucleic acid molecules (e.g., molecules containing DNA nucleotides, RNA nucleotides, or modifications (e.g., modification that increase the stability of the molecule, such as 2′-O-alkyl (e.g., methyl) substituted nucleotides) or combinations thereof) that are complementary to, or that hybridize to, at least a portion of a specific nucleic acid molecule encoding REST (see e.g., Weintraub, H. M., “Antisense DNA and RNA,” Scientific Am. 262:40-46 (1990), which is hereby incorporated by reference in its entirety). SEQ ID NO: 2 above is an exemplary nucleic acid molecule encoding REST. Variant nucleic acid molecules encoding REST are also known in the art, see e.g., NCBI Ref. Seq. NM_001363453 and NM_001193508.1, which are hereby incorporated by reference in their entirety, and are suitable for use in the design of inhibitory nucleic acid antisense molecules. Suitable antisense oligonucleotides for use in the method described herein are, or are up to 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 nucleobases in length and comprise no more than 6, no more than 5, no more than 4, no more than 3, no more than 2, or no more than 1 non-complementary nucleobase(s) relative to the target REST nucleic acid, or specified portion thereof. The antisense nucleic acid molecule hybridizes to its corresponding target REST nucleic acid molecule, to form a double-stranded molecule, which interferes with translation of the mRNA, as the cell will not translate a double-stranded mRNA.
REST antisense nucleic acids can be introduced into cells as antisense oligonucleotides, or can be produced in a cell in which a nucleic acid encoding the antisense nucleic acid has been introduced, for example, using gene therapy methods. Anti-REST antisense oligonucleotides suitable for use in accordance with the methods described herein are disclosed in WO2011031998 to Sedaghat et al., which is hereby incorporated by reference in its entirety.
REST siRNAs are double stranded synthetic RNA molecules approximately 20-25 nucleotides in length with short 2-3 nucleotide 3′ overhangs on both ends. The double stranded siRNA molecule represents the sense and anti-sense strand of a portion of the target mRNA molecule, in this case a portion of the REST nucleotide sequence, i.e., SEQ ID NO: 2 encoding REST isoform 1 or a portion of the nucleotide sequence of another REST isoform (i.e., NCBI Ref. Seq. Nos. NM_001363453 and NM_001193508.1, which are hereby incorporated by reference in their entirety). siRNA molecules are typically designed to target a region of the REST mRNA target approximately 50-100 nucleotides downstream from the start codon. Upon introduction into a cell, the siRNA complex triggers the endogenous RNA interference (RNAi) pathway, resulting in the cleavage and degradation of the target REST mRNA molecule. siRNA molecules that target REST and other members of the REST transcription complex that can be utilized in the methods described herein are disclosed in WO2009027349 to Maes, which is hereby incorporated by reference in its entirety. Various improvements of siRNA compositions, such as the incorporation of modified nucleosides or motifs into one or both strands of the siRNA molecule to enhance stability, specificity, and efficacy, have been described and are suitable for use in accordance with this aspect of the disclosure (see e.g., WO2004/015107 to Giese et al.; WO2003/070918 to McSwiggen et al.; WO1998/39352 to Imanishi et al.; U.S. Patent Application Publication No. 2002/0068708 to Jesper et al.; U.S. Patent Application Publication No. 2002/0147332 to Kaneko et al; U.S. Patent Application Publication No. 2008/0119427 to Bhat et al., which are hereby incorporated by reference in their entirety).
Short or small hairpin RNA molecules are similar to siRNA molecules in function, but comprise longer RNA sequences that make a tight hairpin turn. shRNA is cleaved by cellular machinery into siRNA and gene expression is silenced via the cellular RNA interference pathway. shRNA molecules that effectively interfere with REST expression have been developed, as described herein, and comprise the following nucleic acid sequences: 5′-CCAUUCCAAUGUUGCCACUGC-3′ (SEQ ID NO: 3) targeting the REST nucleotide sequence of 5′-GCAGTGGCAACATTGGAATGG-3′ (SEQ ID NO: 4) and 5′-UCGAUUAGUAUUGUAGCCG-3′ (SEQ ID NO: 5) targeting the REST nucleotide sequence of 5′-CGGCTACAATACTAATCGA-3′ (SEQ ID NO: 6)
Nucleic acid aptamers that specifically bind to REST are also suitable for use in the methods as described herein. Nucleic acid aptamers are single-stranded, partially single-stranded, partially double-stranded, or double-stranded nucleotide sequences, capable of specifically recognizing a selected target molecule, either protein or nucleic acid molecule, by a mechanism other than Watson-Crick base pairing or triplex formation. Aptamers include, without limitation, defined sequence segments and sequences comprising nucleotides, ribonucleotides, deoxyribonucleotides, nucleotide analogs, modified nucleotides, and nucleotides comprising backbone modifications, branchpoints, and non-nucleotide residues, groups, or bridges. An exemplary RNA aptamer known to inhibit REST, which is suitable for use in the accordance with the methods described herein comprises a double stranded RNA molecule as shown below, that contains a sequence corresponding to a 21 base pair DNA element known as the neuron-restrictive silencer element (NRSE) or RE1 (Kuwabara et al., “A Small Modulatory dsRNA Specifies the Fate of Adult Neural Stem Cells,” Cell 116:779-793 (2004), which is hereby incorporated by reference in its entirety.
Modifications to inhibitory nucleic acid molecules described herein, i.e., REST antisense oligonucleotides, siRNA, shRNA, PNA, aptamers, encompass substitutions or changes to internucleoside linkages, sugar moieties, or nucleobases. Modified inhibitory nucleic acid molecules are often preferred over native forms because of desirable properties such as, for example, enhanced cellular uptake, enhanced affinity for nucleic acid target, increased stability in the presence of nucleases, or increased inhibitory activity. For example, chemically modified nucleosides may be employed to increase the binding affinity of a shortened or truncated antisense oligonucleotide for its target nucleic acid. Consequently, comparable results can often be obtained with shorter antisense compounds that have such chemically modified nucleosides.
REST targeted inhibitory nucleic acid molecules can optionally contain one or more nucleosides wherein the sugar group has been modified. Such sugar modified nucleosides may impart enhanced nuclease stability, increased binding affinity or some other beneficial biological property to the nucleic acid molecule. In certain embodiments, nucleosides comprise a chemically modified ribofuranose ring moieties. Examples of chemically modified ribofuranose rings include without limitation, addition of substituted groups, including 5′ and 2′ substituent groups, bridging of non-geminal ring atoms to form bicyclic nucleic acids (BNA), replacement of the ribosyl ring oxygen atom with S, N(R), or C(R1)(R)2, where R=H, C1-C12 alkyl or a protecting group, and combinations thereof. Examples of chemically modified sugars include 2′-F-5′-methyl substituted nucleoside, replacement of the ribosyl ring oxygen atom with with further substitution at the 2′-position.
In certain embodiments, nucleosides are modified by replacement of the ribosyl ring with a sugar surrogate (sometimes referred to as DNA analogs), such as a morpholino ring, a cyclohexenyl ring, a cyclohexyl ring, or a tetrahydropyranyl ring.
Nucleobase (or base) modifications or substitutions are structurally distinguishable from, yet functionally interchangeable with, naturally occurring or synthetic unmodified nucleobases. Both natural and modified nucleobases are capable of participating in hydrogen bonding. Such nucleobase modifications may impart nuclease stability, binding affinity or some other beneficial biological property to REST inhibitor nucleic acid molecules. Modified nucleobases include synthetic and natural nucleobases such as, for example, 5-methylcytosine (5-me-C). Certain nucleobase substitutions, including 5-methylcytosine substitutions, are particularly useful for increasing the binding affinity of a nucleic acid molecule to its target nucleic acid. Additional modified nucleobases include 5-hydroxymethyl cytosine, xanthine, hypoxanthine, 2-aminoadenine, 6-methyl and other alkyl derivatives of adenine and guanine, 2-propyl and other alkyl derivatives of adenine and guanine, 2-thiouracil, 2-thiothymine and 2-thiocytosine, 5-halouracil and cytosine, 5-propynyl (—C≡C—CH3) uracil and cytosine and other alkynyl derivatives of pyrimidine bases, 6-azo uracil, cytosine and thymine, 5-uracil (pseudouracil), 4-thiouracil, 8-halo, 8-amino, 8-thiol, 8-thioalkyl, 8-hydroxyl and other 8-substituted adenines and guanines, 5-halo particularly 5-bromo, 5-trifluoromethyl, 7-methyl guanine and 7-methyladenine, 2-F-adenine, 2-aminoadenine, 8-azaguanine and 8-azaadenine, 7-deazaguanine, 7-deazaadenine, 3-deazaguanine, and 3-deazaadenine.
The naturally occurring internucleoside linkage of RNA and DNA is a 3′ to 5′ phosphodiester linkage. Inhibitory nucleic acid molecules having modified internucleoside linkages include internucleoside linkages that retain a phosphorus atom as well as internucleoside linkages that do not have a phosphorus atom. Representative phosphorus containing internucleoside linkages include, but are not limited to, phosphodiesters, phosphotriesters, methylphosphonates, phosphoramidate, and phosphorothioates. Methods of preparing phosphorous-containing and non-phosphorous-containing linkages are well known. In certain embodiments, an inhibitory nucleic acid molecule targeting a REST nucleic acid comprises one or more modified internucleoside linkages.
The inhibitory nucleic acid molecules described here may be covalently linked to one or more moieties or conjugates which enhance the activity, cellular distribution, or cellular uptake of the resulting inhibitory nucleic acid molecule. Typical conjugate groups include cholesterol moieties and lipid moieties. Additional conjugate groups include carbohydrates, polymers, peptides, inorganic nanostructured materials, phospholipids, biotin, phenazine, folate, phenanthridine, anthraquinone, acridine, fluoresceins, rhodamines, coumarins, and dyes.
Inhibitory nucleic acid molecules described herein can also be modified to have one or more stabilizing groups, e.g., cap structures, that are generally attached to one or both termini of the inhibitory nucleic acid molecule to enhance properties such as, for example, nuclease stability. These terminal modifications protect inhibitory nucleic acid molecules from exonuclease degradation, and can help in delivery and/or localization within a cell. Cap structures can be present at the 5′-terminus (5′-cap), or at the 3′-terminus (3′-cap), or can be present on both termini. Cap structures are well known in the art and include, for example, inverted deoxy abasic caps. Further 3′ and 5′-stabilizing groups that can be used to cap one or both ends of an inhibitory nucleic acid molecule to impart nuclease stability include those disclosed in WO 03/004602 to Manoharan, which is hereby incorporated by reference in its entirety.
In another embodiment, a suitable REST inhibitor is any agent or compound capable of decreasing or preventing the level of nuclear translocation of REST in a glial cell relative to the level of REST nuclear translocation occurring in the absence of the agent.
In another embodiment, a suitable REST inhibitor is any agent or compound capable of antagonizing or decreasing REST suppressor activity in a glial cell relative to the level of REST suppressor activity occurring in the absence of the agent. Agents suitable to achieve REST inhibition in this manner include nucleic acid molecules that encode the DNA binding domain of REST, but lack the two repressor domains of the protein. These agents act as dominant negative REST agents, blocking the interaction of REST with its RE1 sequence in a target gene. Suitable REST dominant negative nucleic acid molecules that can be utilized in the methods described herein are disclosed in Chen et al., “NRSF/REST is Required in vivo for Repression of Multiple Neuronal Target Genes During Embryogenesis,” Nat. Genet. 20: 136-42 (1998) and Roopra et al., “Transcriptional Repression by Neuron-restrictive Silencer Factor is Mediated via the Sin3-histone Deacetylase Complex,” Mol Cell Biol 20: 2147-57 (2000), which are hereby incorporated by reference in their entirety).
In another embodiment, the agent capable of decreasing REST suppressor activity in a glial cell is a benzoimidazole-5-carboxamide derivative (Charbord et al., High Throughput Screening for Inhibitors of REST in Neural Derivatives of Human Embryonic Stem Cells Reveals a Chemical Compound that Promotes Expression of Neuronal Genes,” Stem Cells 31:1816-1828 (2013), which is hereby incorporated by reference in its entirety). Particularly suitable benzoimidazole-5-carboxamide derivatives include, without limitation, 2-(2-Hydroxy-phenyl)-1H-benzoimidazole-5-carboxylic acid allyloxy-amide (X5050) and 2-Thiophen-2-yl-1H-benzoimidazole-5-carboxylic acid (2-ethyl-hexyl)-amide (X5917).
In another embodiment, the agent capable of decreasing REST suppressor activity in a glial cell is a pyrazole propionamide derivative (Charbord et al., High Throughput Screening for Inhibitors of REST in Neural Derivatives of Human Embryonic Stem Cells Reveals a Chemical Compound that Promotes Expression of Neuronal Genes,” Stem Cells 31:1816-1828 (2013), which is hereby incorporated by reference in its entirety). Particularly suitable pyrazole propionamide derivatives include, without limitation, 3-[1-(3-Bromo-phenyl)-3,5-dimethyl-1H-pyrazol-4-yl]-1-{4-[5-(morpholine-4-carbonyl)-pyridin-2-yl]-2-phenyl-piperazin-1-yl}-propan-1-one (X38210), and 3-[1-(2,5-Difluoro-phenyl)-3,5-dimethyl-1H-pyrazol-4-yl]-1-{4-[5-(morpholine-4-carbonyl)-pyridin-2-yl]-2-phenyl-piperazin-1-yl}-propan-1-one (X38207).
In another embodiment, the agent capable of decreasing REST suppressor activity in a glial cell is an antibody or an antibody fragment that binds to and blocks the activity of REST directly, or that binds to any of the proteins of the transcriptional repressor complex and inhibits the formation of the REST transcription complex in a glial cell. Antibodies capable of binding REST and methods of making the same are disclosed in U.S. Pat. No. 6,824,774 to Anders and Schoenherr, which is hereby incorporated by reference in its entirety. Monoclonal antibodies suitable for inhibiting the formation of the REST transcription complex, thereby inhibiting the activity of REST repression include antibodies against BRG-1 associated factor (BAF) 57, BRG1, and BAF170 (Battaglioli et al., “REST Repression of Neuronal Gene Requires Components of the hSWI.SNF Complex,” J. Biol. Chem. 277(43): 41038-45 (2002), which is hereby incorporated by reference in its entirety). Other REST complex components that can be inhibited via antibody binding include, without limitation, MeCP2, mSin3a, AOF2, RCOR1, and JARID1C.
In another embodiment, a suitable REST inhibitor is any agent or compound that inhibits the formation of the REST transcriptional complex in a glial cell. REST-mediated gene repression is achieved by the recruitment of two separate corepressor complexes, i.e., N-terminal and C-terminal corepressor complexes (see Ooi et al., “Chromatin Crosstalk in Development and Disease: Lessons from REST,” Nat Rev Genet 8: 544-54 (2007), which is hereby incorporated by reference in its entirety). Thus, agents or compounds that inhibit the activity of components of these co-repressor complexes are suitable for inhibiting the activity of REST. For example, the histone deacetylases, HDAC1 and HDAC2, are required at both the N-terminal and C-terminal corepressor complexes. Thus, agents that inhibit the activity of these HDACs to inhibit REST activity are suitable for use in the methods described herein. Suitable HDAC inhibitors include, without limitation, valproic acid (VPA), trichostatin A (TSA), suberoylanilide hydroxamic acid (SAHA), N-Hydroxy-4-(Methyl{[5-(2-Pyridinyl)-2-Thienyl]Sulfonyl}Amino)Benzamide,4-Dimethylamino-N-(6 Hydroxycarbamoyethyl)Benzamide-N-Hydroxy-7-(4-Dimethylaminobenzoyl)Aminoheptanamide, 7-[4-(Dimethylamino)Phenyl]-N-Hydroxy-4,6-Dimethyl-7-Oxo-2,4-Heptadienamide, Docosanol, (5)-[5-Acetylamino-1-(2-oxo-4-trifluoromethyl-2H-chromen-7-ylcarbamoyl) pentyljcarbamic acid tert-butyi ester (BATCP), Benzyl ((S)-[1-(4-methyl-2-oxo-2H-chromen-7-ylcarbamoyl)-5-propionyl aminopentyljcarbamate (MOCPAC), and 4-(Dimethylamino)-N-[7-(hydroxyamino)-7-oxoheptyl]-benzamide (M344). Other suitable HDAC inhibitors that can be utilized in the methods described herein to inhibit REST activity are disclosed in WO2009/027349 to Maes et al., which is hereby incorporated by reference in its entirety.
In another embodiment, the REST complex is inhibited using an agent that inhibits the function of other members of the repression complex, including MeCP2, mSin3a, AOF2, RCOR1, JARID1C, BAF57, BAF170, and BRG1. Such agents act by preventing the transcriptional repression complex from binding to the gene promoter or act by preventing members of the complexes from interacting with each other. Suitable agents include inhibitory nucleic acid molecules, e.g., antisense oligonucleotides, siRNA, shRNA, aptamers, as described above, antibodies, and small molecule inhibitors.
In one embodiment, the REST inhibitor used in accordance with the methods described herein is packaged into a nanoparticle delivery vehicle to effectuate delivery of the inhibitor to glial cells of a subject, i.e., a glial cell targeted REST inhibitor. Suitable nanoparticle delivery vehicles for delivering REST inhibitors across the blood brain barrier and/or to glial cells include, without limitation, liposome, protein nanoparticles, polymeric nanoparticles, metallic nanoparticles, and dendrimers.
Liposomes are spherical vesicles composed of phospholipid and steroid (e.g., cholesterol) bilayers that are about 80-300 nm in size. Liposomes are biodegradable with low immunogenicity. The REST inhibitor as described herein can be incorporated into liposomes using the encapsulation process. The liposomes are taken up by target cells by adsorption, fusion, endocytosis, or lipid transfer. Release of the REST inhibitor from the liposome depends on the liposome composition, pH, osmotic gradient, and surrounding environment. The liposome can be designed to release the REST inhibitor in a cell organelle specific manner to achieve, for example, nuclear delivery of the REST inhibitor.
Methods and types of liposomes that can be utilized to deliver the REST inhibitors described herein to glial cells are known in the art, see e.g., Liu et al., “Paclitaxel loaded liposomes decorated with a multifunctional tandem peptide for glioma targeting,” Biomaterials 35:4835-4847 (2014); Gao et al. “Glioma targeting and blood-brain barrier penetration by dual-targeting doxorubincin liposomes,” Biomaterials 34:5628-5639 (2013); Zong et al., “Synergistic dual-ligand doxorubicin liposomes improve targeting and therapeutic efficacy of brain glioma in animals,” Mol Pharm. 11:2346-2357 (2014); Yemisci et al., “Systemically administered brain-targeted nanoparticles transport peptides across the blood-brain barrier and provide neuroprotection,” J Cerebr Blood F Met. 35:469-475 (2015), which are hereby incorporated by reference in their entirety.
In another embodiment, the REST inhibitors described herein are packaged in a polymeric delivery vehicle. Polymeric delivery vehicles are structures that are typically about 10 to 100 nm in diameter. Suitable polymeric nanoparticles for encapsulating the REST inhibitors as described herein can be made of synthetic polymers, such as poly-ε-caprolactone, polyacrylamine, and polyacrylate, or natural polymers, such as, e.g., albumin, gelatin, or chitosan. The polymeric nanoparticles used herein can be biodegradable, e.g., poly(L-lactide) (PLA), polyglycolide (PGA), poly(lactic acid-co-glycolic acid) (PLGA), or non-biodegradable, e.g., polyurethane. The polymeric nanoparticles used herein can also contain one or more surface modifications that enhance delivery. For example, in one embodiment, the polymeric nanoparticles are coated with nonionic surfactants to reduce immunological interactions as well as intermolecular interactions. The surfaces of the polymeric nanoparticles can also be functionalized for attachment or immobilization of one or more targeting moieties as described infra, e.g., an antibody or other binding polypeptide or ligand that directs the nanoparticle across the blood brain barrier and/or to glial cells for glial cell uptake (i.e., glia progenitor or astrocyte uptake).
Methods and types of polymeric nanoparticles that can be utilized to deliver the REST inhibitors as described herein to glial cells are known in the art, see e.g., Koffie et al. “Nanoparticles enhance brain delivery of blood-brain barrier-impermeable probes for in vivo optical and magnetic resonance imaging,” Proc Natl Acad Sci USA. 108:18837-18842 (2011); Zhao et al., “The permeability of puerarin loaded poly(butylcyanoacrylate) nanoparticles coated with polysorbate 80 on the blood-brain barrier and its protective effect against cerebral ischemia/reperfusion injury,” Biol Pharm Bull. 36:1263-1270 (2013); Yemisci et al., “Systemically administered brain-targeted nanoparticles transport peptides across the blood-brain barrier and provide neuroprotection,” J Cerebr Blood F Met. 35:469-475 (2015), which are hereby incorporated by reference in their entirety.
In another embodiment, the composition of the present disclosure is packaged in a dendrimer nanocarrier delivery vehicle. Dendrimers are unique polymers with a well defined size and structure. Exemplary nanometric molecules having dendritic structure that are suitable for use as a delivery vehicle for the REST inhibitor as described herein include, without limitation, glycogen, amylopectin, and proteoglycans. Methods of encapsulating therapeutic compositions, such as the composition described herein, in the internal structure of dendrimers are known in the art, see e.g., D'Emanuele et al., “Dendrimer-drug interactions,” Adv Drug Deliv Rev 57: 2147-2162 (2005), which is hereby incorporated by reference in its entirety. The surface of dendrimers is suitable for the attachment of one or more targeting moieties, such as antibodies or other binding proteins and/or ligands as described herein capable of targeting the dendrimers across the blood brain barrier and/or to glial cells.
An exemplary dendrimer for encapsulation of a REST inhibitor for administration and delivery to a subject in need thereof is poly(amido amide) (PAMAM). PAMAM has been utilized for the delivery of both protein and nucleic acid therapeutics to target cells of interest. Methods of encapsulating therapeutic agents in PAMAM and utilization of PAMAM for delivering therapeutic agents to the central nervous system are also known in the art and can be utilized herein, see e.g., Cerqueira et al., “Multifunctionalized CMCht/PAMAM dendrimer nanoparticles modulate the cellular uptake by astrocytes and oligodendrocytes in primary cultures of glial cells,” Macromol Biosci. 12:591-597 (2012); Nance et al., “Systemic dendrimer-drug treatment of ischemia-induced neonatal white matter injury,” J Control Release 214:112-120 (2015); Natali et al., “Dendrimers as drug carriers: dynamics of PEGylated and methotrexate-loaded dendrimers in aqueous solution,” Macromolecules 43:3011-3017 (2010); Han et al., “Peptide conjugated PAMAM for targeted doxorubicin delivery to transferrin receptor overexpressed tumors,” Mol Pharm 7: 2156-2165 (2010); Kannan et al., “Dendrimer-based Postnatal Therapy for Neuroinflammation and Cerebral Palsy in a Rabbit Model,” Sci. Transl. Med. 4:130 (2012); and Singh et al., “Folate and Folate-PEG-PAMAM dendrimers: synthesis, characterization, and targeted anticancer drug delivery potential in tumor bearing mice,” Bioconjugate Chem 19, 2239-2252 (2008), which is hereby incorporated by reference in its entirety.
In another embodiment, the REST inhibitor as disclosed herein is packaged in a silver nanoparticle or an iron oxide nanoparticle. Methods and preparations of silver and iron oxide nanoparticles that can be utilized to deliver a REST inhibitor described herein to glia cells are known in the art, see e.g, Hohnholt et al., “Handling of iron oxide and silver nanoparticles by astrocytes,” Neurochem Res. 38:227-239 (2013), which is hereby incorporated by reference in its entirety.
In another embodiment, a REST inhibitor as described herein is packaged in gold nanoparticles. Gold nanoparticles are small particles (<50 nm) that enter cells via an endocytic pathway. In one embodiment, the gold nanoparticles are coated with glucose to facilitate transfer of the nanoparticles across the blood brain barrier and uptake of the nanoparticles by astrocytes via the GLUT-1 receptor as described by Gromnicova et al., “Glucose-coated Gold Nanoparticles Transfer across Human Brain Endothelium and Enter Astrocytes In vitro,” PLoS ONE 8(12): e81043 (2013), which is hereby incorporated by reference in its entirety.
In another embodiment, the composition of the present disclosure is packaged in silica nanoparticles. Silica nanoparticles are biocompatible, highly porous, and easily functionalized. Silica nanoparticles are amorphous in shape, having a size range of 10-300 nm. Silica nanoparticles that are suitable to deliver a therapeutic composition, such as a REST inhibitor to the CNS for glial cell uptake are known in the art, see e.g., Song et al., “In vitro Study of Receptor-mediated Silica Nanoparticles Delivery Across Blood Brain Barrier,” ACS Appl. Mater. Interfaces 9(24):20410-20416 (2017); Tamba et al., “Tailored Surface Silica Nanoparticles for Blood-Brain Barrier Penetration: Preparation and In vivo Investigation,” Arabian J. Chem. doi.org/10.1016/j.arabjc.2018.03.019 (2018), which are hereby incorporated by reference in their entirety.
In another embodiment, the REST inhibitor is packaged into a protein nanoparticle delivery vehicle. Protein nanoparticles are biodegradable, metabolizable, and are easily amenable to modification to allow entrapment of therapeutic molecules or compositions and attachment of targeting molecules if desired. Suitable protein nanoparticle delivery vehicles that are known in the art and have been utilized to deliver therapeutic compositions to the central nervous system include, without limitation, albumin particles (see e.g., Lin et al., “Blood-brain Barrier Penetrating Albumin Nanoparticles for Biomimetic Drug Delivery via Albumin-Binding Protein Pathway for Antiglioma Therapy,” ACS Nano 10(11): 9999-10012 (2016), and Ruan et al., “Substance P-modified Human Serum Albumin Nanoparticles Loaded with Paclitaxel for Targeted Therapy of Glioma,” Acta Pharmaceutica Sinica B 8(1): 85-96 (2018), which are hereby incorporated by reference in their entirety), gelatin nanoparticles (see e.g., Zhao et al., “Using Gelatin Nanoparticle Mediated Intranasal Delivery of Neuropeptide Substance P to Enhance Neuro-Recovery in Hemiparkinsoninan Rats,” PLoS One 11(2): e0148848 (2016), which is hereby incorporated by reference in its entirety), and lactoferrin nanoparticles (see e.g., Kumari et al., “Overcoming Blood Brain Barrier with Dual Purpose Temozolomide Loaded Lactoferrin Nanoparticles for Combating Glioma (SERP-17-12433),” Scientific Reports 7: 6602 (2017), which is hereby incorporated by reference in its entirety).
Nanoparticle mediated delivery of a therapeutic composition can be achieved passively (i.e., based on the normal distribution pattern of liposomes or nanoparticles within the body) or by actively targeting delivery. Actively targeted delivery involves modification of the delivery vehicle's natural distribution pattern by attaching a targeting moiety to the outside surface of the liposome. In one embodiment, a delivery vehicle as described herein is modified to include one or more targeting moieties, i.e., a targeting moiety that facilitates delivery of the liposome or nanoparticle across the blood brain barrier and/or a targeting moiety that facilitates glial cell uptake (i.e., glial progenitor cell uptake and/or astrocyte uptake). In one embodiment, a delivery vehicle as described herein is surface modified to express a targeting moiety suitable for achieving blood brain barrier penetration. In another embodiment, a delivery vehicle as described herein is surface modified to express a targeting moiety suitable for glial cell uptake. In another embodiment, a delivery vehicle as described herein is surface modified to express dual targeting moieties.
Targeting moieties that facilitate delivery of the liposome or nanoparticle across the blood brain barrier take advantage of receptor-mediated, transporter-mediated, or adsorptive-mediated transport across the barrier. Suitable targeting moieties for achieving blood brain barrier passage include antibodies and ligands that bind to endothelial cell surface proteins and receptors. Exemplary targeting moieties include, without limitation, cyclic RGD peptides (Liu et al, “Paclitaxel loaded liposomes decorated with a multifunctional tandem peptide for glioma targeting,” Biomaterials 35:4835-4847 (2014), which is hereby incorporated by reference in its entirety), a cyclic A7R peptide that binds to VEGFR2 and neuropilin-1 (Ying et al., “A Stabilized Peptide Ligand for Multifunctional Glioma Targeted Drug Delivery,” J Contr. Rel. 243:86-98 (2016), which is hereby incorporated by reference in its entirety), a transferrin protein, peptide, or antibody capable of binding to the transferrin receptors (Zong et al., “Synergistic dual-ligand doxorubicin liposomes improve targeting and therapeutic efficacy of brain glioma in animals,” Mol Pharm. 11:2346-235773 (2014); Yemisci et al., “Systemically administered brain-targeted nanoparticles transport peptides across the blood-brain barrier and provide neuroprotection,” J Cerebr Blood F Met. 35:469-475 (2015); and Wei et al., “Brain Tumor-targeted Therapy by Systemic Delivery of siRNA with Transferrin Receptor-Mediated Core-Shell Nanoparticles,” Inter. J. Pharm 510(1): 394-405), Niewoehner et al., “Increased Brain Penetration and Potency of a Therapeutic Antibody Using a Monovalent Molecular Shuttle,” Neuron 81:49-60 (2014), which are hereby incorporated by reference in in their entirety), a folate protein or peptide that binds the folate receptor (Gao et al. “Glioma targeting and blood-brain barrier penetration by dual-targeting doxorubincin liposomes,” Biomaterials 34:5628-5639 (2013), which is hereby incorporated by reference in its entirety), a lactoferrin protein or peptide that binds the lactoferrin receptor (Song et al., “In vitro Study of Receptor-mediated Silica Nanoparticles Delivery Across Blood Brain Barrier,” ACS Appl. Mater. Interfaces 9(24):20410-20416 (2017), which is hereby incorporated by reference in its entirety), low density lipoprotein receptor ligands, such ApoB and ApoE (Wagner et al., “Uptake Mechanisms of ApoE-modified Nanoparticles on Brain Capillary Endothelial Cells as a Blood-brain Barrier Model,” PLoS One 7:e32568 (2012), which is hereby incorporated by reference in its entirety), substance P peptide (Ruan et al., “Substance P-modified Human Serum Albumin Nanoparticles Loaded with Paclitaxel for Targeted Therapy of Glioma,” Acta Pharmaceutica Sinica B 8(1): 85-96 (2018), which is hereby incorporated by reference in its entirety), and an angiopep-2 (An2) peptide (Demeule et al., “Conjugation of a brain-penetrant peptide with neurotensin provides antinociceptive properties,” J. Clin. Invest. 124:1199-1213 (2014), which is hereby incorporated by reference in its entirety). Other suitable targeting moieties include ligands of the amino acid transporters, e.g., glutathione for transport via the glutathione transporter (Rip et al., “Glutathione PEGylated Liposomes: Pharmacokinetics and Delivery of Cargo Across the Blood-Brain Barrier in Rats,” J. Drug Target 22:460-67 (2014), which is hereby incorporated be reference in its entirety), and choline derivatives for delivery via the choline transporter (Li et al., “Choline-derivative-modified Nanoparticles for Brain-targeting Gene Delivery,” Adv. Mater. 23:4516-20 (2011), which is hereby incorporated by reference in its entirety).
A second targeting moiety is one that facilitates glial cell delivery and uptake. Suitable targeting moieties to effectuate astrocyte uptake include, without limitation, low density lipoprotein (LDL) receptor ligands or peptides thereof capable of binding the LDL receptor and oxidized LDL receptor on astrocytes (Lucarelli et al, “The Expression of Native and Oxidized LDL Receptors in Brain Microvessels is Specifically Enhanced by Astrocyte-derived Soluble Factor(s),” FEBS Letters 522(1-3): 19-23 (2002), which is hereby incorporated by reference in its entirety), glucose or other glycans capable of binding the GLUT-1 receptor on astrocytes (Gromnicova et al., “Glucose-coated Gold Nanoparticles Transfer across Human Brain Endothelium and Enter Astrocytes In vitro,” PLoS ONE 8(12): e81043 (2013), which is hereby incorporated by reference in its entirety), and platelet derived growth factor or peptide thereof capable of binding PDGFRα of glial progenitor cells.
Glial cell delivery of inhibitory nucleic acid molecules as described herein, e.g., REST antisense oligonucleotides, REST siRNA, REST shRNA, can also be achieved by packaging such nucleic acid molecules in viral vectors. Several viral vectors are known to inherently target astrocytes in vivo, e.g., lentiviral vectors (Colin et al., “Engineered Lentiviral Vector Targeting Astrocytes In vivo,” Glia 57:667-679 (2009), and Cannon et al., “Pseudotype-dependent Lentiviral Transduction of Astrocytes or Neurons in the Rat Substantia Nigra,” Exp. Neurol. 228:41-52 (2011), which are hereby incorporated by reference in their entirety), and adeno-associated virus vectors (Furman et al., “Targeting Astrocytes Ameliorates Neurologic Changes in a Mouse Model of Alzheimer's Disease,” J. Neurosci. 32: 16129-40 (2012), which is hereby incorporated by reference in its entirety), and are thus suitable for effectuating delivery of the nucleic acid REST inhibitory molecules in accordance with the methods described herein.
As used herein, “treating” or “treatment” includes the administration of a REST inhibitor to restore or depress, partially or wholly, potassium channel gene expression in glial cells, restore, partially or wholly, potassium channel uptake activity in glial cells, and restore, partially or wholly, potassium homeostasis in glial cells and the surrounding tissue. With respect to treating a subject having a neuropsychiatric condition, “treating” includes any indication of success in amelioration of the condition, including any objective or subjective parameter such as abatement, remission, diminishing of symptoms (e.g., decreasing neuronal excitability), or making the condition more tolerable to the patient (e.g., seizure incident); slowing the progression of the condition; making the condition less debilitating; or improving a subject's physical or mental well-being. The treatment or amelioration of symptoms can be based on objective or subjective parameters; including the results of a physical examination, neurological examination, and/or psychiatric evaluation.
As referred to herein “under conditions effective” refers to the effective dose, route of administration, frequency of administration, formulation of REST inhibitor, etc. that play a role in achieving the desired therapeutic benefit for the subject. An effective dose of a REST inhibitor to restore K+ uptake by glial cells in a subject and/or to treat or inhibit the onset of a neuropsychiatric disorder in a subject is the dose of a REST inhibitor that is effective to depress potassium channel gene expression partially or wholly, which in turn will restore potassium channel uptake function (partially or wholly) to permit restoration of brain potassium homeostasis. In instances where the REST inhibitor is administered to a subject having a neuropsychiatric disorder, such as schizophrenia, an effective dose is the dose that restores brain potassium homeostasis to a level sufficient to decrease the extracellular levels of potassium, decrease neuronal excitability, and/or decrease seizure incident. A dosage effective to treat a subject having a neuropsychiatric disorder is the dosage effective to improve disordered cognition in the subject. The effective dose for a particular subject varies, for example, depending upon the health and physical condition of the individual to be treated, the mental and emotional capacity of the individual, the stage of the disorder, the type of REST inhibitor, the route of administration, the formulation, the attending physician's assessment of the medical situation, and other relevant factors.
In one embodiment, the glial cells having impaired K+ uptake are glial progenitor cells. As demonstrated in the Examples herein, REST upregulation in glial progenitor cells suppresses K+ channel gene expression and subsequently K+ uptake by glial progenitor cells. The decrease in K+ uptake inhibits terminal glial progenitor cell differentiation. Thus, in one embodiment, an effective dose of a REST inhibitor is the dose that potentiates astroglial maturation by glial progenitor cells, which reduces, eliminates, or inhibits the onset of a neuropsychiatric disease, symptoms of the neuropsychiatric disease, or side effects of a disease.
In another embodiment, the glial cells having impaired K+ uptake are astrocytes. REST inhibition in astrocytes restores K+ uptake and subsequent K+ homeostasis in the affected astrocytes. REST inhibition in astrocytes of a subject having a neuropsychiatric disease (where potassium channel expression and function is altered) reduces neuronal excitability, decreases seizure incidence, and improves disordered cognition. Thus, treatment with an effective dose of a REST inhibitor decreases, alleviates, arrests, or inhibits development of the symptoms or conditions associated with schizophrenia, autism spectrum disorder, bipolar disorder, or any other neuropsychiatric disorder. Treatment may be prophylactic to prevent or delay the onset or worsening of the disease, condition or disorder, or to prevent the manifestation of clinical or subclinical symptoms thereof. Alternatively, treatment may be therapeutic to suppress and/or alleviate symptoms after the manifestation of the disease, condition or disorder.
A REST inhibitor useful for restoring glial cell K+ uptake in a subject, for example, in a subject having a neuropsychiatric condition, may be administered parenterally via intracerebral delivery, intrathecal delivery, intranasal delivery, or via direct infusion into brain ventricles.
In one embodiment, parenteral administration is by infusion. Infused REST inhibitors may be delivered with a pump. In certain embodiments, broad distribution of the infused REST inhibitor is achieved by delivery to the cerebrospinal fluid by intracranial administration, intrathecal administration, or intracerebroventricular administration.
In certain embodiments, an infused REST inhibitor is delivered directly to a tissue. Examples of such tissues include the striatal tissue, the intracerebroventricular tissue, and the caudate tissue. Specific localization of a REST inhibitor may be achieved by direct infusion to a targeted tissue.
In some embodiments, parenteral administration is by injection. The injection may be delivered with a syringe or a pump. In certain embodiments, the injection is a bolus administered directly to a tissue. Examples of such tissues include the striatal tissue, the intracerebroventricular tissue, and the caudate tissue. Specific localization of pharmaceutical agents, including antisense oligonucleotides, can be achieved via injection to a targeted tissue.
In some embodiments, specific localization of the REST inhibitor, such as a REST antisense oligonucleotide, to a targeted tissue improves the pharmacokinetic profile of the inhibitor as compared to broad diffusion of the same. The specific localization of the REST inhibitor improves potency compared to broad diffusion of the inhibitor, requiring administration of less inhibitor to achieve similar pharmacology. “Similar pharmacology” refers to the amount of time that the target REST mRNA and/or target REST protein is down-regulated/inhibited (e.g. duration of action). In certain embodiments, methods of specifically localizing a REST inhibitor, such as by bolus injection, decreases median effective concentration (EC50) of the inhibitor by a factor of about 20.
In another embodiment, the REST inhibitor as described herein is co-administered with one or more other pharmaceutical agents. According to this embodiment of the disclosure, such one or more other pharmaceutical agents are designed to treat the same disease, disorder, or condition, or one or more symptoms associated therewith, as the REST inhibitor described herein. In one embodiment, the one or more other pharmaceutical agents are designed to treat an undesired side effect of one or more pharmaceutical compositions of the present disclosure. In one embodiment, a REST inhibitor as described herein is co-administered with another pharmaceutical agent to treat an undesired effect. In another embodiment, a REST inhibitor as described herein is co-administered with another pharmaceutical agent to produce a combinational effect. In another embodiment, a REST inhibitor as described herein is co-administered with another pharmaceutical agent to produce a synergistic effect.
In one embodiment, a REST inhibitor as described herein and another pharmaceutical agent are administered at the same time. In another embodiment a REST inhibitor as described herein and another pharmaceutical agent are administered at different times. In another embodiment, a REST inhibitor as described herein and another pharmaceutical agent are prepared together in a single formulation. In another embodiment, a REST inhibitor as described herein and another pharmaceutical agent are prepared separately.
In some embodiments, pharmaceutical agents that may be co-administered with a REST inhibitor as described herein include antipsychotic agents, such as, e.g., haloperidol, chlorpromazine, clozapine, quetapine, and olanzapine; antidepressant agents, such as, e.g., fluoxetine, sertraline hydrochloride, venlafaxine and nortriptyline; tranquilizing agents such as, e.g., benzodiazepines, clonazepam, paroxetine, venlafaxin, and beta-blockers; and mood-stabilizing agents such as, e.g., lithium, valproate, lamotrigine, and carbamazepine.
Preferences and options for a given aspect, feature, embodiment, or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, features, embodiments, and parameters of the invention.
Patient identification, protection and sampling. Patients from which induced pluripotent stem cell (iPSC) derived glial progenitor cells (GPCs) were derived were diagnosed with disabling degrees of schizophrenia with onset in early adolescence. All patients and their guardians were consented/assented by a child and adolescent psychiatrist and under an approved protocol of the University Hospitals Case Medical Center Institutional Review Board, blinded as to subsequent line designations. No study investigators had access to patient identifiers.
Cell sources and lines Schizophrenia-derived iPSC lines were produced from subjects with childhood-onset schizophrenia, and control lines were produced from age- and gender-appropriate control subjects. All iPSC lines were derived as previously reported (Windrem et al., “Human iPSC Glial Mouse Chimeras Reveal Glial Contributions to Schizophrenia,” Cell Stem Cell 21:195-208.e6 (2017), which is hereby incorporated by reference in its entirety). An additional control line (C27) was generously provided by Dr. Lorenz Studer (Memorial Sloan-Kettering). Control-derived lines included: CWRU-22, -17, -37, -208, and C27; SCZ-derived lines included CWRU-8, -51, -52, -193, -164, -29, -30, and -31 (Table 1). CWRU-51/52 and CWRU-29/30/31 comprised different lines from the same patients, and were assessed to estimate inter-line variability from single patients. All iPSCs were generated from fibroblasts by retroviral expression of Cre-excisable Yamanaka factors (Oct4, Sox2, Klf4, c-Myc) (Takahashi et al., “Induction of Pluripotent Stem Cells From Adult Human Fibroblasts by Defined Factors,” Cell 131:861-872 (2007), which is hereby incorporated by reference in its entirety), with validation of pluripotency and karyotypic stability as described (Windrem et al., “Human iPSC Glial Mouse Chimeras Reveal Glial Contributions to Schizophrenia,” Cell Stem Cell 21:195-208.e6 (2017), which is hereby incorporated by reference in its entirety).
hiPSC culture and passage. hiPSCs were cultured on irradiated mouse embryonic fibroblasts (MEFs), in 0.1% gelatin coated 6-well plates with 1-1.2 million cells/well in hES medium (see below) supplemented with 10 ng/ml bFGF (Invitrogen, 13256-029). Media changes were performed daily, and cells passaged at 80% confluence, after 4-7 days of culture. For hiPSC passage, cells were first incubated with 1 ml collagenase (Invitrogen, 17104-019) at 37° C. for 3-5 minutes, and then cells were transferred into a 15 ml tube for centrifuge with 3 minutes. The pellet was re-suspended with ES medium with bFGF, and was plated onto new irradiated MEFs at 1:3-1:4.
GPC and astrocytic generation from hiPSCs. When hiPSCs reached 80% confluence, they were incubated with 1 ml Dispase (Invitrogen, 17105-041) to permit the generation of embryoid bodies (EBs); these were cultured in ES medium without bFGF for 5 days. At DIVE, EBs were plated onto poly-ornithine (Sigma, P4957) and laminin (VWR, 47743)-coated dishes, and cultured in neural induction media (NIM; see below) (Wang et al., “Human iPSC-Derived Oligodendrocyte Progenitor Cells Can Myelinate and Rescue a Mouse Model of Congenital Hypomyelination,” Cell Stem Cell 12:252-264 (2013), which is hereby incorporated by reference in its entirety), supplemented with 20 ng/ml bFGF, 2 μg/ml heparin and 10 μg/ml laminin for 10 days.
At DIV25, the EBs were gently scraped with a 2 ml glass pipette, then cultured in NIM plus 1 μM purmorphamine (Calbiochem, 80603-730) and 0.1 μM RA (Sigma, R2625). At DIV33, NPCs appeared and were serially switched to NIM with 1 μM purmorphamine and 10 ng/ml bFGF for 7 days, followed by glial induction medium (GIM) (Wang et al., “Human iPSC-Derived Oligodendrocyte Progenitor Cells Can Myelinate and Rescue a Mouse Model of Congenital Hypomyelination,” Cell Stem Cell 12:252-264 (2013), which is hereby incorporated by reference in its entirety), with 1 μM purmorphamine for another 15 days. At DIV56, the resultant glial spheres were mechanically cut with microsurgical blades under a dissection microscope, and switched to GIM with 10 ng/ml PDGF, 10 ng/ml IGF, and 10 ng/ml NT3, with media changes every 2 days. At DIV150-180, GPCs were incubated with mouse anti-CD44 microbeads (1:50), and then incubated with rabbit anti-mouse IgG2a+b micro-beads (1:100) and further sorted by magnetic cell sorting (MACS) with a magnetic stand column. The CD44+ cells were then directed into astrocytes in M41 supplemented with 10% FBS plus 20 ng/mL BMP4 for 3 weeks.
Media recipes are listed in Table 2 (base, hESC and neural media) and Table 3 (Glial and Astrocyte induction media).
FACS/MACS sorting. Cells were incubated with Accutase for 5 minutes at 37° C. to obtain a single cell suspension, and then spun down at 200RCF for 10 minutes. These GPCs were re-suspended in cold Miltenyi Wash buffer with primary antibody (phycoerythrin (PE)-conjugated mouse anti-CD140a, 1:50, for FACS; mouse anti-CD140a, 1:100, for MACS), and incubated on ice for 30 min, gently swirling every 10 minutes. After primary antibody incubation, these cells were then washed and either incubated with a secondary antibody (rabbit anti-mouse IgG2a+b micro-beads, 1:100) followed by sorting on a magnetic stand column for MACS, or directly sorted by FACS on a FACSAria IIIu (Becton-Dickinson). The sorted cells were counted and plated onto poly-ornithine- and laminin-coated 24-well plate for further experiments. The primary and secondary antibodies are listed in Table 4.
RT-PCR Total RNA was extracted from cell lines with miRNeasy mini kit (Qiagen, 217004), and then was reversely transcribed into cDNA with Taqman Reverse Transcription kit (N808-0234). The relative expression of mRNA was measured by the Bio-RAD S6048, which was further normalized to the expression of 18S mRNA. The primer sequences are listed in Table 5.
In vitro immunocytochemistry Cells were first fixed with 4% paraformaldehyde for 5 minutes at room temperature. After washing with PBS with thimerosal for 3 times, cells were penetrated with 0.1% saponin plus 1% of either goat or donkey serum for 15 minutes at room temperature. Cells were further blocked with 5% of either goat or donkey serum plus 0.05% saponin for 15 minutes at RT. After incubation with primary antibodies at 4° C. overnight, these cells were incubated with secondary antibodies for 30 minutes at RT. The primary and secondary antibodies are listed in Table 6.
Molecular cloning shRNAs of human REST (target sequences: GCAGTGGCAACATTGGAATGG (SEQ ID NO: 4) or CGGCTACAATACTAATCGA (SEQ ID NO: 6)) were cloned into the vector pTANK-EF1a-CoGFP-Puro-WPRE immediately downstream puromycin. The human cDNA of REST (a gift from Stephen Elledge, Addgene plasmid 41903) (Westbrook et al., “SCFbeta-TRCP Controls Oncogenic Transformation and Neural Differentiation Through REST Degradation,” Nature 452:370-374 (2008), which is hereby incorporated by reference in its entirety) was cloned immediately after EF 1 a promoter in the vector pTANK-EF1a-IRES-mCherry-WPRE (Benraiss et al., “Human Glia Can Both Induce and Rescue Aspects of Disease Phenotype in Huntington Disease,” Nat. Commun. 7:11758 (2016), which is hereby incorporated by reference in its entirety). The lentiviral vector allowed for expression of REST in tandem with the reporter mCherry.
The final constructs were validated for the correct insertion by sequencing. The plasmids were co-transfected with pLP-VSV (Invitrogen, K497500) and psPAX2 (a gift from Didier Trono, Addgene plasmid 12260) into 293FT cells (Fisher Scientific, R70007) through X-tremeGENE (Roche, 06366236001) for lentiviral generation. The supernatant of 293T cells were collected and spun down at 76000RCF for 3 hours to concentrate virus (Beckman, L8-70, Ultracentrifuge). A 10-fold serial dilution of virus was prepared and transduced to 293T cells, and fluorescent colonies were counted for determination of viral titration. MACS sorted CD44+ cells were transduced with Lenti-REST or control virus, each at 1 MOI (multiplicities of infection) for 4 hours.
Potassium uptake Astrocytes were plated onto poly-ornithine- and laminin-coated 24-well plates with 30,000 cells/well. For the potassium uptake assay, astrocytes were incubated with 86Rb (1.0-3.3uCi/well) for 15 min, and then they were washed three time with ice-cold artificial cerebrospinal fluid (aCSF, 500 uL/well). For cell lysis, 0.5N NaOH (200 uL/well) was put into each well, which was put into 5 ml cocktail liquid (Ultima Gold, Fisher Scientific, 509050575) and measured by scintillation counter (Beckman Coulter, LS6500), and the results were normalized to both total protein (BCA Protein Assay Kit, Fisher Scientific, 23227) and cell number (Hemocytometer, Fisher Scientific, 02-671-54). The aCSF solution contained (in mM) 124 NaCl, 2.5 KCl, 1.75 NaH2PO4, 2 MgCl2, 2 CaCl2, 0.04 Vit.C, 10 glucose and 26 NaHCO3, pH 7.4.
iPSCs were produced from skin samples obtained from patients with childhood-onset schizophrenia, as well as healthy young adult controls free of known mental illness, as previously described (Windrem et al., “Human iPSC Glial Mouse Chimeras Reveal Glial Contributions to Schizophrenia,” Cell Stem Cell 21:195-208.e6 (2017), which is hereby incorporated by reference in its entirety). Patient identifiers were not available to investigators besides the treating psychiatrist, although age, gender, race, diagnosis and medication history accompanied cell line identifiers. Briefly, fibroblasts were isolated from each sample. From these, 8 hiPSC lines were derived from patient samples and normal controls (5 juvenile-onset schizophrenia patients and 3 healthy gender-matched and age-analogous controls (Table 1). iPSCs were generated using excisable floxed polycistronic hSTEMCCA lentivirus (Somers et al., “Generation of Transgene-Free Lung Disease-Specific Human Induced Pluripotent Stem Cells Using a Single Excisable Lentiviral Stem Cell Cassette,” Stem Cells 28:1728-1740 (2010); Zou et al., “Establishment of Transgene-Free Induced Pluripotent Stem Cells Reprogrammed From Human Stem Cells of Apical Papilla for Neural Differentiation,” Stem Cell Res. Ther. 3:43 (2012), which are hereby incorporated by reference in their entirety) encoding Oct4, Sox2, Klf4 and c-Myc (Takahashi et al., “Induction of Pluripotent Stem Cells From Adult Human Fibroblasts by Defined Factors,” Cell 131:861-872 (2007); Welstead et al., “Generating iPS Cells From MEFS Through Forced Expression of Sox-2, Oct-4, c-Myc, and Klf4,” J. Vis. Exp. (14):734 (2008), which are hereby incorporated by reference in their entirety). All lines were validated as pluripotent using RNA sequencing and immunolabeling to assess pluripotent gene expression. The identity of each iPSC line was confirmed to match the parental donor fibroblasts using short tandem repeat (STR)-based DNA fingerprinting, and each line was karyotyped to confirm genomic integrity. A fourth hiPSC control line, C27 (Chambers et al., “Highly Efficient Neural Conversion of Human ES and iPS Cells by Dual Inhibition of SMAD Signaling,” Nature Biotechnology 27:275-280 (2009), which is hereby incorporated by reference in its entirety), was also used, to ensure that all genomic and phenotypic data were consistent with prior work (Wang et al., “Human iPSC-Derived Oligodendrocyte Progenitor Cells Can Myelinate and Rescue a Mouse Model of Congenital Hypomyelination,” Cell Stem Cell 12:252-264 (2013), which is hereby incorporated by reference in its entirety).
Glial differentiation efficiency of cells derived from SCZ patients and control subjects (n=4 lines from 4 different patients, each with ≥3 repeats/patient, each versus paired control) was compared by instructing these iPSC cells to GPC fate as previously described (Wang et al., “Human iPSC-Derived Oligodendrocyte Progenitor Cells Can Myelinate and Rescue a Mouse Model of Congenital Hypomyelination,” Cell Stem Cell 12:252-264 (2013), which is hereby incorporated by reference in its entirety), and assessing their expression of stage-specific markers of maturation as a function of time. All tested iPSCs were found to exhibit typical colonies, and express markers of pluripotency by flow cytometry, including SSEA4 (
At that point, these SCZ- and CTR-derived GPCs were further differentiated into astrocytes after incubating in M41 medium with 20 ng/ml BMP4 for 3 weeks. Immunolabeling revealed that the proportion of GFAP+ astrocytes was significantly higher in control lines (4 CTR lines, n≥3/each line, means of 4 CTR lines/70.1%±2.4%) than in SCZ lines (4 SCZ lines, n≥3/each line, means of 4 SCZ lines/39.9%±2.0%; P<0.001 by two tailed t-test) (
To identify the molecular concomitants to the defective astrocytic differentiation of SCZ GPCs, RNA-seq on FACS-sorted CD140a+ GPCs from 3 different CTR- and 4 SCZ-derived lines at time points ranging from 154 to 242 days in vitro had been performed (Windrem et al., “Human iPSC Glial Mouse Chimeras Reveal Glial Contributions to Schizophrenia,” Cell Stem Cell 21:195-208.e6 (2017), which is hereby incorporated by reference in its entirety). mRNA was isolated from these cells with polyA-selection for RNA sequencing on an Illumina HiSeq 2500 platform for approximately 45 million 1×100 bp reads per sample. The original counts were analyzed to determine disease-dysregulated genes at 5% FDR and log 2 fold change >1. By that means, 118 mRNAs that were consistently and significantly differentially expressed by CD140 assorted SCZ hGPCs relative to their control iPSC hGPCs had been identified (Windrem et al., “Human iPSC Glial Mouse Chimeras Reveal Glial Contributions to Schizophrenia,” Cell Stem Cell 21:195-208.e6 (2017), which is hereby incorporated by reference in its entirety). Among these, a number of genes involved in glial lineage progression were downregulated in SCZ hGPCs, relative to their normal controls, suggesting that astroglial differentiation was impaired in SCZ in a cell autonomous fashion, due to intrinsic defects in SCZ-derived glial progenitor cells.
Together with the impaired astrocytic differentiation of SCZ GPCs, the RNA-seq data suggested that those astrocytes that do successfully differentiate might nonetheless be functionally impaired. In particular, the RNA-seq revealed the downregulated transcription in SCZ GPCs of a broad set of potassium channel (KCN)-encoding genes, including the Na+—K+ ATPase, Na+-K+/2Cl− cotransporter (NKCC), and Kir-family inwardly rectifying potassium channels (
On the basis of these genomic data, whether K+ uptake was actually impaired in SCZ astrocytes was assessed. To address this hypothesis, qPCR was used to confirm whether these K+ channel-associated genes were dysregulated in SCZ glia. They were indeed significantly down regulated, thus validating the RNA-seq analysis (
Since several genes involved in Na+/K+-ATPase, Na+/K+/2Cl− cotransporter, and inwardly rectifying K+ channels were dysregulated in SCZ glia, the drugs ouabain, bumetanide, and tertiapin were used to respectively block these three potassium uptake mechanisms. The actions of these drugs on astrocytes had not been previously assessed, so different concentrations of each were first tested to determine optimal dose ranges for modulating astroglial K+ uptake. Ouabain and bumetanide, respectively, targeting the Na+/K+-ATPase and Na+/K+/2Cl− cotransporters, significantly inhibited K+ uptake in CTR glia, while tertiapin, which targets Kir channels, did not (
Since a large number of potassium channel-encoding genes are dysregulated in SCZ glia, it is difficult to modulate glial K+ uptake through genetic means targeting individual potassium channels alone. To address this issue, Biobase-Transfac analysis was used. This analysis was developed to identify regulatory regions common to different genes, as a means of defining their shared upstream regulators (Hu et al., “Genome-Wide Identification of Transcription Factors and Transcription-Factor Binding Sites in Oleaginous Microalgae Nannochloropsis,” Sci. Rep. 4:5454 (2014), which is hereby incorporated by reference in its entirety). By this means, shared regulatory elements within 1 kb of the transcription start sites (TSS) of the SCZ-associated glial genes were identified in the data sets. The intent was to identify upstream transcription factors able to modulate these genes as a group. Using a 13 nucleotide consensus sequence (CCNNGGTGCTGAA; SEQ ID NO: 21), it was determined that the majority of all down-regulated potassium channel genes were targets of the neuron restrictive silencing factor (NKSF) REST (
To test this postulate, lentivirus was used to overexpress REST in CTR glial cells, and K+ uptake by the transduced cells was assessed. In parallel, REST expression in SCZ glial cells was knocked down through lentiviral shRNAi transduction, and similarly K+ uptake in these cells was assessed. qPCR validation confirmed that REST was significantly modulated as intended in both CTR and SCZ glial cells, respectively (
Importantly, REST-overexpressing CTR astrocytes mimicked the functional potassium dysregulation of SCZ glia, in that their K+ uptake was significantly reduced compared to that of non-transduced CTR glia (
The data herein indicate that astrocytic differentiation is impaired in GPCs derived from childhood onset schizophrenics, and that this maturational defect may be rescued by the de-repression of glial differentiation-associated transcription via REST knock-down. Importantly, astrocytic depletion has been recently noted in both cortical and subcortical regions of patients with schizophrenia, and this might be especially prominent in the white matter, (Rajkowska et al., “Layer-Specific Reductions in GFAP-Reactive Astroglia in the Dorsolateral Prefrontal Cortex in Schizophrenia,” Schizophr. Res. 57:127-138 (2002); Steffek et al., “Cortical Expression of Glial Fibrillary Acidic Protein and Glutamine Synthetase is Decreased in Schizophrenia,” Schizophr. Res. 103:71-82 (2008); Williams et al., “Astrocyte Decrease in the Subgenual Cingulate and Callosal Genu in Schizophrenia,” Eur. Arch. Psychiatry Clin. Neurosci. 263:41-52 (2013), which are hereby incorporated by reference in their entirety). Astrocytes play key contributions to neural circuit formation and stability (Christopherson et al., “Thrombospondins are Astrocyte-Secreted Proteins That Promote CNS Synaptogenesis,” Cell 120: 421-433 (2005); Clarke & Barres, “Emerging Roles of Astrocytes in Neural Circuit Development,” Nature Reviews Neuroscience 14:311-321 (2013), which are hereby incorporated by reference in their entirety). Thus, any such developmental defect of astrocytic differentiation in SCZ GPCs might lead to profound defects in the initial formation or stability of neural circuits, a defect that is one of the hallmarks of schizophrenia (Penzes et al., “Dendritic Spine Pathology in Neuropsychiatric Disorders,” Nat. Neurosci. 14:285-293 (2011), which is hereby incorporated by reference in its entirety).
Glial maturation is precisely regulated in human brain development (Goldman & Kuypers, “How to Make an Oligodendrocyte,” Development 142:3983-3995 (2015); Molofsky et al., “Astrocytes and Disease: A Neurodevelopmental Perspective,” Genes & Development 26:891-907 (2012), which are hereby incorporated by reference in their entirety). Astrocytes have a multitude of roles in the CNS, including energy support to both neurons and oligodendrocytes, potassium buffering, neurotransmitter recycling, and synapse formation and maturation (Blanco-Suarez et al., “Role of Astrocyte-Synapse Interactions in CNS Disorders,” J. Physiol. 595:1903-1916 (2017); Clarke & Barres, “Emerging Roles of Astrocytes in Neural Circuit Development,” Nature Reviews Neuroscience 14:311-321 (2013); Verkhratsky et al., “Why are Astrocytes Important?” Neurochemical Research 40:389-401 (2015), which are hereby incorporated by reference in their entirety). As such, astrocytes play critical roles in neural circuit formation and maintenance. Astrocytes also contribute to the glymphatic system through the regulation of cerebral spinal fluid flow (Xie et al., “Sleep Drives Metabolite Clearance From the Adult Brain,” Science 342:373-377 (2013), which is hereby incorporated by reference in its entirety). Thus, the delayed differentiation of SCZ astrocytes may have significant effects on neural network formation, organization and mature function alike.
A number potassium channels were down-regulated in SCZ glia. Interestingly, prior genome wide association studies have identified an association of potassium channel genes with schizophrenia. For instance, the chromosome 1q21-q22 locus, containing KCNN3, has a significant linkage to familial schizophrenia (Brzustowicz et al., “Location of a Major Susceptibility Locus for Familial Schizophrenia on Chromosome 1q21-q22,” Science 288:678-682 (2000), which is hereby incorporated by reference in its entirety). KCNN3 is widely express in the human brain, and selectively regulates neuronal excitability and neurotransmitter release in monoaminergic neurons (O'Donovan & Owen, “Candidate-Gene Association Studies of Schizophrenia,” Am. J. Hum. Genet. 65:587-592 (1999), which is hereby incorporated by reference in its entirety). In addition to KCNN3, a number of other potassium channel genes have been associated with schizophrenia, including KCNQ2 and KCNAB1 (Lee et al., “Pathway Analysis of a Genome-Wide Association Study in Schizophrenia,” Gene 525:107-115 (2013), which is hereby incorporated by reference in its entirety). More recently, a novel de novo mutation in ATP1A3, a subunit of the sodium-potassium pump, has been specifically associated with childhood-onset schizophrenia (Smedemark-Margulies et al., “A Novel De Novo Mutation in ATP1A3 and Childhood-Onset Schizophrenia,” Cold Spring Harb. Mol. Case Stud 2:a001008 (2016), which is hereby incorporated by reference in its entirety).
The down-regulation or dysfunction of these potassium channel genes in GPCs and their derived astrocytes may contribute significantly to disease phenotype in schizophrenia. Potassium channel genes are widely expressed in both GPCs (Coppi et al., “UDP-Glucose Enhances Outward K(+) Currents Necessary for Cell Differentiation and Stimulates Cell Migration by Activating the GPR17 Receptor in Oligodendrocyte Precursors,” Glia 61:1155-1171 (2013); Maldonado et al., “Oligodendrocyte Precursor Cells are Accurate Sensors of Local K+ in Mature Gray Matter,” J. Neurosci. 33:2432-2442 (2013), which are hereby incorporated by reference in their entirety) and astrocytes (Larsen et al., “Contributions of the Na(+)/K(+)-ATPase, NKCC1, and Kir4.1 to Hippocampal K(+) Clearance and Volume Responses,” Glia 62:608-622 (2014); Zhang & Barres, “Astrocyte Heterogeneity: An Underappreciated Topic in Neurobiology,” Current Opinion in Neurobiology 20:588-594 (2010), which are hereby incorporated by reference in their entirety), in which they regulate not only proliferation, migration, and differentiation, but also the relationship of glia to neurons (Coppi et al., “UDP-Glucose Enhances Outward K(+) Currents Necessary for Cell Differentiation and Stimulates Cell Migration by Activating the GPR17 Receptor in Oligodendrocyte Precursors,” Glia 61:1155-1171 (2013); Maldonado et al., “Oligodendrocyte Precursor Cells are Accurate Sensors of Local K+ in Mature Gray Matter,” J. Neurosci. 33:2432-2442 (2013), which are hereby incorporated by reference in their entirety). In regards to the latter, astrocytes also regulate synaptic K+ uptake through Na+/K+-ATPase, NKCC, and the inwardly rectifying Kir channels (Larsen et al., “Contributions of the Na(+)/K(+)-ATPase, NKCC1, and Kir4.1 to Hippocampal K(+) Clearance and Volume Responses,” Glia 62:608-622 (2014); Zhang & Barres, “Astrocyte Heterogeneity: An Underappreciated Topic in Neurobiology,” Current Opinion in Neurobiology 20:588-594 (2010), which are hereby incorporated by reference in their entirety), thereby establishing neuronal firing thresholds over broad regional domains. In addition, dysregulated potassium channel genes have been associated with a broad variety of neurological and psychiatric diseases. Several Kir genes, including Kir4.1, are involved in astrocytic potassium buffering and glutamate uptake, and deletion of these genes has been noted in both Huntington's disease and multiple sclerosis (Seifert et al., “Astrocyte Dysfunction in Neurological Disorders: A Molecular Perspective,” Nat. Rev. Neurosci. 7:194-206 (2006); Tong et al., “Astrocyte Kir4.1 Ion Channel Deficits Contribute to Neuronal Dysfunction in Huntington's Disease Model Mice,” Nat. Neurosci. 17:694-703 (2014), which are hereby incorporated by reference in their entirety). In addition, mutation of astrocytic ATP1A2, the a2 isoform of the sodium-potassium pump, may be causally associated with familial hemiplegic migraine (Bottger et al., “Glutamate-System Defects Behind Psychiatric Manifestations in a Familial Hemiplegic Migraine Type 2 Disease-Mutation Mouse Model,” Sci. Rep. 6:22047 (2016); Swarts et al., “Familial Hemiplegic Migraine Mutations Affect Na,K-ATPase Domain Interactions,” Biochim. Biophys. Acta 1832:2173-2179 (2013), which are hereby incorporated by reference in their entirety). In all of these examples, glial K+ uptake is impaired, just as in SCZ glia, and all are associated with elements of phenotypic hyperexcitability. Indeed, elevated extracellular K+ has been shown to alter the neuronal excitability and neural circuit stability in a mouse model of schizophrenia (Crabtree et al., “Alteration of Neuronal Excitability and Short-Term Synaptic Plasticity in the Prefrontal Cortex of a Mouse Model of Mental Illness,” J. Neurosci. 37(15):4158-4180 (2017), which is hereby incorporated by reference in its entirety). Thus, the decreased K+ uptake of SCZ glia may be a significant contributor to schizophrenia pathogenesis, especially in regards to those schizophrenic phenotypes associated with hyperexcitability and seizure disorders, which would be potentiated in the setting of disrupted potassium homeostasis.
The upregulated REST in SCZ glia appears to be both necessary and sufficient for the suppression of both potassium channel gene expression and potassium uptake. REST, as a transcriptional repressor, regulates neural gene expression in both neurons and glia (Bruce et al., “Genome-Wide Analysis of Repressor Element 1 Silencing Transcription Factor/Neuron-Restrictive Silencing Factor (REST/NRSF) Target Genes,” Proc. Nat'l. Acad. Sci. U.S.A. 101:10458-10463 (2004); Dewald et al., “The RE1 Binding Protein REST Regulates Oligodendrocyte Differentiation,” J. Neurosci. 31:3470-3483 (2011), which are hereby incorporated by reference in their entirety). In broad terms, REST represses neural genes through its recruitment of CoREST and mSIN3a, the complex of which further recruits HDAC1/2 and methyltransferase G9a to promote concurrent histone deacetylation and methylation, which together serve to block transcription (Hirabayashi & Gotoh, “Epigenetic Control of Neural Precursor Cell Fate During Development,” Nat. Rev. Neurosci. 11:377-388 (2010), which is hereby incorporated by reference in its entirety). As such, the misdirected upregulation of REST inhibits potassium channel gene expression, and thereby contributes to the disease phenotype of those disorders associated with dysregulated potassium homeostasis and its attendant neuronal hyperexcitability. For instance, up-regulated REST in peripheral sensory neurons induces the downregulation of KCNQ2, which in turn potentiates the hyperexcitability of sensory neurons and hence the maintenance of neuropathic pain (Rose et al., “Transcriptional Repression of the M Channel Subunit Kv7.2 in Chronic Nerve Injury,” Pain 152:742-754 (2011), which is hereby incorporated by reference in its entirety). REST similarly represses KCNQ3 gene expression, and the down regulation of KCNQ3 by REST provokes neuronal hyperexcitability in specific neonatal epilepsies (Mucha et al., “Transcriptional Control of KCNQ Channel Genes and the Regulation of Neuronal Excitability,” J. Neurosci. 30:13235-13245 (2010), which is hereby incorporated by reference in its entirety).
Furthermore, REST is involved in schizophrenia through its modulation of miR137 (Warburton et al., “Characterization of a REST-Regulated Internal Promoter in the Schizophrenia Genome-Wide Associated Gene MIR137,” Schizophr. Bull. 41:698-707 (2015), which is hereby incorporated by reference in its entirety), which regulates multiple schizophrenia-associated genes, including CACNA1C, TCF4, and ANK3 (Kwon et al., “Validation of Schizophrenia-Associated Genes CSMD1, C10orf26, CACNA1C and TCF4 as miR-137 Targets,” Mol. Psychiatry 18:11-12 (2013), which is hereby incorporated by reference in its entirety; Schizophrenia Psychiatric Genome-Wide Association Study (GWAS) Consortium, “Genome-Wide Association Study Identifies Five New Schizophrenia Loci,” Nat. Genet. 43:969-976 (2011), which are hereby incorporated by reference in their entirety). Other investigators have reported that REST can repress the expression of potassium channel-associated genes (Bruce et al., “Genome-Wide Analysis of Repressor Element 1 Silencing Transcription Factor/Neuron-Restrictive Silencing Factor (REST/NRSF) Target Genes,” Proc. Nat'l. Acad. Sci. U.S.A. 101:10458-10463 (2004), which is hereby incorporated by reference in its entirety), and can suppress oligodendroglial differentiation within the glial lineage (Dewald et al., “The RE1 Binding Protein REST Regulates Oligodendrocyte Differentiation,” J. Neurosci. 31:3470-3483 (2011), which is hereby incorporated by reference in its entirety). Thus, it was hypothesized that pathologically high levels of REST might repress K+ channel associated gene expression, and thereby decrease K+ uptake, in schizophrenia-derived glia. This would be expected to lead to high interstitial K+, and hence to relative neuronal hyperexcitability and network desynchronization. That said, the role of REST in disordered glial potassium homeostasis has never before been reported. The data herein suggest the likelihood that some fraction of schizophrenic patients might suffer high interstitial K+ levels, as a function of diminished glial potassium uptake. This would be expected to yield neuronal hyperexcitability, as has been reported Huntington disease, another disorder characterized by glial potassium channel dysfunction (Benraiss et al., “Human Glia Can Both Induce and Rescue Aspects of Disease Phenotype in Huntington Disease,” Nat. Commun. 7:11758 (2016), which is hereby incorporated by reference in its entirety). As such, the observation of a REST-dependent impairment of K+ uptake by SCZ derived glia indicates that REST is an effective target for the treatment of schizophrenia
In that regard, several REST-targeted drugs have been developed for epilepsy and Huntington disease, including valproic acid and X5050 (Charbord et al., “High Throughput Screening for Inhibitors of REST in Neural Derivatives of Human Embryonic Stem Cells Reveals a Chemical Compound That Promotes Expression of Neuronal Genes,” Stem Cells 31:1816-1828 (2013); Graff & Tsai, “The Potential of HDAC Inhibitors as Cognitive Enhancers,” Annu. Rev. Pharmacol. Toxicol. 53:311-330 (2013), which are hereby incorporated by reference in their entirety). The data herein indicates that these agents may have therapeutic utility in schizophrenia as well. In that regard, it was noted that ouabain and bumetanide significantly inhibited K+ uptake by both CTR astrocytes and SCZ astrocytes following REST knockdown, and yet neither affected the uptake of K+ by astrocytes transduced to over-express REST. These data suggest that the suppression of K+ uptake in SCZ glia by REST is through the suppression of potassium channel gene expression. A corollary of that observation is that modulators of K+ uptake might have real value in the treatment of schizophrenia (Calcaterra et al., “Schizophrenia-Associated hERG Channel Kv11.1-3.1 Exhibits a Unique Trafficking Deficit that is Rescued Through Proteasome Inhibition for High Throughput Screening,” Sci. Rep. 6:19976 (2016); He et al., “Current Pharmacogenomic Studies on hERG Potassium Channels,” Trends Mol. Med. 19:227-238 (2013); Rahmanzadeh et al., “Lack of the Effect of Bumetanide, a Selective NKCC1 Inhibitor, in Patients With Schizophrenia: A Double-Blind Randomized Trial,” Psychiatry Clin. Neurosci. 71:72-73 (2017), which are hereby incorporated by reference in their entirety). Thus, the data herein reveal the defective differentiation of astrocytes by SCZ GPCs, the REST-dependent suppression of potassium channel genes and consequent defective uptake of K+ by SCZ astrocytes. The resultant deficiencies in synaptic potassium homeostasis may be expected to significantly lower neuronal firing thresholds while accentuating network desynchronization (Benraiss et al., “Human Glia Can Both Induce and Rescue Aspects of Disease Phenotype in Huntington Disease,” Nat. Commun. 7:11758 (2016), which is hereby incorporated by reference in its entirety). As such, these findings identify a causal contribution of astrocytic pathology to the neuronal dysfunction of SCZ, and by so doing suggests a set of tractable molecular targets for its treatment
Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the disclosure and these are therefore considered to be within the scope of the disclosure as defined in the claims which follow.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/686,346 filed Jun. 18, 2018, which is hereby incorporated by reference in its entirety.
This invention was made with government support under R01 MH099578 awarded by the National Institutes of Health. The government has certain rights in this invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/037754 | 6/18/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62686346 | Jun 2018 | US |
