Patent Application
20210269780
The present application is being filed along with a Sequence Listing in electronic format. The Sequence Listing is provided as a file entitled PRIN-63876 ST25.TXT, created Jul. 11, 2019, which is approximately 28,287 bytes in size. The information in the electronic format of the Sequence Listing is incorporated herein by reference in its entirety.
The present invention relates to a system and method for treating individuals to modulate the assembly of stress granules in the individual, and specifically for providing particular proteins that modulate dimerization and other interactions associated with G3BP1/2 and other key stress granule proteins in a way that allows for the up- and down-regulation of stress granule assembly.
G3BP refers to two homologous human proteins termed G3BP1 and G3BP2. G3BP includes an RNA-binding domain (RBD), an internal disordered region, and a dimerization/oligomerization domain. In G3BP, the dimerization/oligomerization domain consists of amino acids 1-142 of G3BP1 or amino acids 1-133 of G3BP2 (hereinafter referred to as “NTF2-like” domains). Data suggests that viruses interfere with oligomerization of G3BP1/2 to prevent the formation of stress granules, which typically act as platforms to relay protective cell death-initiating signals to prevent continued viral replication.
Stress granules are micron-sized membrane-less condensates composed of RNA and protein that form, e.g., upon stressful environmental perturbations. Persistent stress granule assembly or perturbed dynamics likely plays a critical role in initiating the characteristic protein pathology observed in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), frontotemporal degeneration (FTD), inclusion body myopathies (IBM), and potentially Alzheimer's disease (AD). Not surprisingly, various cancers have evolved related strategies to promote tumor viability, counter-intuitively by stabilizing critical RNAs via G3BP upregulation. Thus, there is an urgent public health need to develop rationally designed therapeutic approaches that interfere with the assembly or dynamics of stress granules.
Currently, treatments that prevent, cure, or prolong lifespan are non-existent in the context of human neurodegenerative diseases. Brain diseases associated with perturbed RNA homeostasis represent a particularly formidable challenge, since most are caused by conversion of an essential physiological protein (e.g., TDP43) to a self-replicating form that ultimately kills the brain cell (i.e., neuron) via protein loss-of-function or poorly understood gain-of-function. A simple strategy proposed for many neurodegenerative diseases associated with such “protein misfolding” is to get rid of the toxic protein using genetic strategies. This is a viable approach for diseases caused by proteins that feature redundancy with respect to their function or are not important for the adult nervous system. Unfortunately, however, most proteins that accumulate in diseases of RNA homeostasis (e.g., ALS, FTD, IBM) are essential RNA-binding molecules with diverse cellular functions. Proximal proteins (e.g., G3BP) in the formation of stress granules are similarly problematic targets. Thus, therapeutics aimed at reducing their levels (e.g., siRNA, shRNA, antisense oligonucleotides) are likely to cause significant unwanted consequences if used in patients.
Thus, a system and method for modulating stress granule assembly is desirable.
A first aspect of the present disclosure is a protein construct that can be used to modulate stress granule assembly. The protein construct is configured to penetrate a cell and bind with the G3BP1 (or G3BP2) NTF2-like domain. To do so, the protein construct includes a cell penetrating protein fused to between 1 and 10 additional proteins that dimerize with a NTF2 domain or interact with dimerized NTF2-like domains, where the additional proteins could be one or more of: the first m amino acids of G3BP1 where m is between 8 and 334, and preferably between 8 and 142, the first n amino acids of G3BP2 where n is between 8 and 330, and preferably between 8 and 133, or a peptide variant having any of the forms: (1) Xy-FGDF-Xy; (2) Xy-FGEF-Xy; or (3) Xy-FGSF-Xy, where Xy is 1 to y additional amino acids. In some embodiments, y≤1500, y≤1000, y≤500, y≤100, y≤50. In preferred embodiments, y≤25. In more preferred embodiments, y≤10. Optionally, the cell penetrating protein may also be fused to a protein tag, such as a fluorescent protein. A plasmid may be constructed that expresses the protein construct.
A second aspect of the present disclosure is a method for treating patients with a disease or infection. The method involves providing a protein construct configured to penetrate a cell and bind with an NTF2-like domain or NTF2-like dimer, such as the protein construct described previously. The protein construct is then appropriately introduced to the patient, such as by injecting a solution or other fluid containing the protein construct at a location that allows the protein fragment to modulate pathological stress granule assembly, where the protein construct may be in a solution or other fluid. The protein construct is then allowed to penetrate a cell and interact with at least one NTF2-like monomer or dimer within the cell. Where the protein construct is configured to only bind with a single NTF2-like domain, such dimerization will diminish the formation of stress granules. Where the protein construct is configured to simultaneously interact with two or more NTF2-like domains, such interactions will upregulate the formation of stress granules, by facilitating the formation of a connected network of interactions required for phase separation and stress granule condensation. Optionally, the patient will have a neurodegenerative disease or disorder of cell proliferation (e.g., various cancers). Optionally, the protein construct may be injected into cerebrospinal fluid. Optionally, the protein construct may hinder at least one homotypic or heterotypic interaction in the organism between an essential stress granule nucleator and the protein construct or associating binding partners without causing immediate cell toxicity. Optionally, the protein construct may be introduced as a prophylactic treatment. Optionally, the protein construct may be introduced as an active treatment of a viral infection.
As used herein, articles such as “a” and “an” when used in a claim, are understood to mean one or more of what is claimed or described.
As used herein, the term “about [a number]” is intended to include values rounded to the appropriate significant digit. Thus, “about 1” would be intended to include values between 0.5 and 1.5, whereas “about 1.0” would be intended to include values between 0.95 and 1.05.
As used herein, the term “at least one” means one or more and thus includes individual components as well as mixtures/combinations.
As used herein, the terms “include”, “includes” and “including” are meant to be non-limiting.
As used herein, the term “cell penetrating protein” is meant to include both cell penetrating proteins and cell penetrating peptides.
G3BP can exist as dimers that interact with a number of additional RNA-binding proteins via its NTF2-like dimerization domain to form large-scale phase-separated or aggregated biomolecular condensates/assemblies. In stressed cells, such assemblies, organized around G3BP dimers via interactions with the NTF2-like domain, recruit other components such as ribosomal subunits and RNA, which enter the system following stress-dependent ribosome disassembly. The end result of this process is the formation of micron-sized RNA-protein assemblies (“stress granules”) that can be observed by microscopy. The continued presence of stress granules can impair physiology and cause the characteristic protein pathologies observed in neurodegenerative diseases such as ALS. Alternatively, they may promote cell viability in rapidly proliferating cells associated with cancer. Stress granules are primarily composed of RNA but also contain characteristic RNA-binding proteins and oligomerized G3BP.
The disclosed system and method seek to treat diverse human diseases by preventing the first step in stress granule assembly (G3BP dimerization or complex formation with other RNA-binding proteins via NTF2-like domain binding interface) while minimizing unwanted side effects or toxicity associated with genetic ablation of the protein culprits driving disease pathogenesis.
G3BP is an essential nucleator of stress granule assembly. The RBD and NTF2-like domain are both critical to its function in the assembly of stress granules. The present disclosure takes advantage of the discovery that the assembly of stress granules can be modulated by introducing specifically configured protein constructs that are used to bind with the NTF2-like domains.
A first aspect of the present disclosure is a protein construct that can be used to modulate stress granule assembly. Referring to
The first segment (110) should comprise a cell penetrating protein (CPP). Any appropriate CPP known to those of skill in the art are envisioned. As an example, the CPP may be a positively charged peptide and may be selected from the group consisting of (1) trans-activator of transcription (TAT) (SEQ ID NO: 1), (b) penetratin (SEQ ID NO: 2), (c) polyarginine, (d) polylysine, or (e) an oligopeptide comprising at least about 70% of histidine, lysine, and/or arginine. In addition, the CPP may comprise a protein transduction domain (PTD) and may also be a cell permeable protein.
The second segment (120) should comprise between 1 and 10 additional proteins (“binding proteins”) (121, 122) (as used herein, “proteins” includes both full-length proteins and protein fragments) that can bind with the NTF2-like domain in a G3BP1 or G3BP2 protein. In some preferred embodiments, the number of additional binding proteins is 1 or 2. While the additional binding proteins may be identical, they may also each be a different full-length protein or protein fragment.
The second segment (120) specifically modulate the formation of stress granules (i.e. G3BP dimerization or oligomerization of it and associated proteins), preferably without disrupting RNA-binding protein abundance.
Referring to
Referring to
The additional binding proteins may include, but are not limited to, (i) the first m amino acids of G3BP1 (SEQ ID NO.: 1) where m is between 8 and 334 (a sequence consisting of the first 334 amino acids can be referred to as G3BP1 ΔRBD), and preferably between 8 and 142; or (ii) the first n amino acids of G3BP2 (SEQ ID NO.: 2) where m is between 8 and 330 (a sequence consisting of the first 330 amino acids can be referred to as G3BP2 ΔRBD), and preferably between 8 and 133. A sequence consisting of the first 142 amino acids of G3BP1 is hereinafter referred to as “G3BPdi” (G3BP dimer inhibitor).
In action, these binding proteins can be used to modulate the formation of stress granules. In one example, human HEK293 cells expressing a fluorescent marker of stress granules (PABPC1-EYFP) were treated with 1 mM sodium arsenite for 2 hours. Cells expressing a negative control (mCherry-sspB, a fluorescent fusion protein) were used and compared to cells expressing the negative control placed on the end of G3BPdi (G3BPdi-mCherry-sspB). After the sodium arsenite treatment, the percentage of cells with stress granules was quantified.
Referring to
However, since at high expression levels, cell growth defects and occasional cell death was observed, preferred G3BP fragments have less than 142 amino acids. Based on structural knowledge of G3BP-substrate binding, other appropriate proteins can be identified. For example, two factors (USP10 and CAPRIN1) that tune stress granule dynamics, compete for binding at specific interfaces in the first 124 amino acids of G3BP. Further, viral proteins featuring FGDF peptides, and possibly also related FGEF and FGSF are thought to perturb G3BP oligomerization at similar locations.
With this understanding, the additional binding proteins may alternatively utilize specific amino acid residues from G3BP1, G3BP2, USP10 and/or viral proteins with FGDF-motifs, where those specific amino acid residues may be important for oligomerization and/or interaction with other proteins that mediate higher-order complex assembly.
It is believed that these specific amino acid residues from G3BP1/2 may include K5, L10, V11, F15, R32, F33, K123, and F124. As such, peptide variants that specifically target these residues may also be utilized. In some embodiments, all eight residues are preferentially bound. In some embodiments, seven of the eight residues are bound. In some embodiments, six of the eight residues are bound. In some embodiments, five of the eight residues are bound. In some embodiments, four of the eight residues are bound.
The additional binding proteins from USP10 and/or viral proteins with FGDF-motifs may include, but are not limited to, a peptide variant having any of the forms: (1) Xy-FGDF-Xy; (2) Xy-FGEF-Xy; or (3) Xy-FGSF-Xy, where Xy is 1 to y additional amino acids. In some embodiments, y≤1500, y≤1000, y≤500, y≤100, y≤50. In preferred embodiments, y≤20. In more preferred embodiments, y≤10.
Referring back to
DNA fragments encoding sequences of interest, without the cell penetrating proteins, were amplified by PCR with Phusion® High-Fidelity DNA Polymerase (NEB). Oligonucleotides used for PCR were synthesized by IDT. In-Fusion HD cloning kit (Clonetech) was used to insert the PCR amplified fragments into (A) AscI (NEB restriction enzyme)-linearized FM5-mGFP-AscI site vector; (B) AscI (NEB restriction enzyme)-linearized FM5-mCherry-AscI site vector; and (C) AscI (NEB restriction enzyme)-linearized FM5-miRFP670-AscI site vector. Cloning products were confirmed by GENEWIZ sequencing, sequencing from both ends of the insert. In addition to a stop sequence after each insert, inserts included: (A) G3BP1 NTF2-like domain (the first 142 amino acids in G3BP1); (B) G3BP1 ΔRBD (the first 334 amino acids in G3BP1); (C) USP10 FGDF motif ×1 [PQYIFGDFSP DEFNQFFVTP RSSVELP] (SEQ ID NO.: 5); and (D) USP10 FGDF motif ×2 [PQYIFGDFSP DEFNQFFVTP RSSVELPSSGSGSGS PQYIFGDFSP DEFNQFFVTP RSSVELP] (SEQ ID NO.: 6). A cell penetrating protein can be incorporated into the inserts above, using standard, known techniques.
In an example illustrating the ability to reduce stress granule assembly, G3BP1 and UBAP2L (SEQ ID NO.: 7) are considered. Human U2OS cells both in untreated conditions and following arsenite-induced translational arrest and subsequent polysome disassembly. In wild-type (WT) cells, 400 μM arsenite treatment for 1-2 hours causes the formation of stress granules, as visualized by well-established stress granule markers. G3BP1/2 double-knockout U2OS cells were co-transduced to express mGFP-UBAP2L 467-540 (which is an FG-rich G3BP interaction domain) and G3BP1-mCherry. In cells featuring high UBAP2L 467-540 (
It is believed that NTF2-associated proteins collectively contribute the high RBD valency essential for stress granule condensation. Moreover, excess concentration of partners that lack RBDs (e.g., USP10, truncated G3BP, etc.) may inhibit this phase transition by out-competing binding of RBD-containing proteins (e.g., CAPRIN1 (SEQ ID NO.: 8)). It is hypothesized that USP10 acts as a molecular shut-off valve for this system by causing a significant decrease in the RBD valency of the network, possibly by cutting protein-protein cross-links between G3BP nodes or “capping” the network. It is believed that such an off-switch would occur independently of additional weak RNA cross-links between oligomeric RBP nodes, and that strong multivalent NTF2-NTF2 interactions between engineered structures would be sufficient for phase separation of the associated protein network. In another experiment, structures comprising G3BP ΔRBD were co-expressed with CAPRIN1-iRFP (i.e., a G3BP NTF2-binding partner with RBD) or USP10-iRFP (i.e., NTF2-associated partner without RBD that competes for binding with CAPRIN1 and possibly other RBPs that confer additive valency to complex). As seen in
In an example illustrating the ability to increase stress granule assembly, the USP10 FGDF motif ×2 and YBX1 (SEQ ID NO.: 9) are considered. YBX1 is an RNA-binding protein that marks stress granules and does not require G3BP1 NTF2-like domain for entry. Whereas the USP10 FGDF motif ×1 inhibits stress granule formation, the USP10 FGDF motif ×2 promotes stress granule biogenesis by cross-linking G3BP dimers into extended complexes that retain ability to interact with RNA. Wild-type U2OS cells were co-transduced with mGFP-USP10 FGDF motif ×2 and YBX1-mCherry. Even in the absence of stress (i.e. non-treated), stress granules (800) are observed for both the USP10 FGDF motif ×2 (
Also disclosed is a plasmid configured to express the protein construct described above. In one embodiment, the protein construct may be cloned into a custom lentiviral vector, allowing stable integration of the DNA into dividing human cells. The protein construct was expressed in mammalian cells using standard protocols of non-replication competent lentivirus infection and subsequent genomic integration. A gene map of a plasmid that expresses the binding proteins (but without the cell penetrating protein) can be seen in reference to
Also disclosed is a method of treating a disease or infection in a patient. In some cases, the patient has a neurodegenerative disease or disorder of cell proliferation (e.g., various cancers). In some cases, the method is a method for actively treating a disease or infection (e.g., actively treating a viral infection). In some cases, the method is used as a prophylactically treatment.
Referring to
The first step (610) is to provide a protein construct that is configured to penetrate a cell and bind with an NTF2-like domain. In some embodiments, the protein construct is provided by itself. In some embodiments, the protein construct is present in a fluid that is suitable for injection. The fluid may comprise water. In some embodiments, what may be provided is, e.g., a sterile package containing a fluid comprising less than 30% by weight of the protein construct.
The second step (620) is to introduce the protein construct (which includes any composition that comprises the protein construct) to a patient. This may be done by any appropriate technique known to those of skill in the art. In some embodiments the protein construct may be administered, e.g., orally, transdermally, or via intramuscular, subcutaneous, or intradermal injection. In some embodiments, the protein construct is injected into cerebrospinal fluid.
The third step (630) is to allow the protein construct to modulate pathological stress granule assembly. In some embodiments, where the protein construct consists of a single protein that binds with NTF2-like domains, the protein construct downregulates the formation of stress granules. In some embodiments, where the protein construct consists of two or more proteins that binds with NTF2-like domains, the protein construct upregulates the formation of stress granules.
In some embodiments, the protein construct hinders at least one homotypic or heterotypic interaction in the organism between an essential stress granule nucleator and itself or associating binding partners, preferably without causing immediate cell toxicity.
Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.
This application claims priority to U.S. Provisional Application No. 62/697,691, filed Jul. 13, 2018, and U.S. Provisional Application No. 62/719,751, filed Aug. 20, 2018, both of which are herein incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US19/41564 | 7/12/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62697691 | Jul 2018 | US | |
| 62719751 | Aug 2018 | US |
