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Bahat A, Itzhaki E, Weiss B, Tolmasov M, Tsoory M, Kuperman Y, Brandis A, Shurrush KA, Dikstein R. Lowering mutant huntingtin by small molecules relieves Huntington's disease symptoms and progression. EMBO Mol Med 2024; 16:523-546. [PMID: 38374466 PMCID: PMC10940305 DOI: 10.1038/s44321-023-00020-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 11/21/2023] [Accepted: 12/07/2023] [Indexed: 02/21/2024] Open
Abstract
Huntington's disease (HD) is an incurable inherited disorder caused by a repeated expansion of glutamines in the huntingtin gene (Htt). The mutant protein causes neuronal degeneration leading to severe motor and psychological symptoms. Selective downregulation of the mutant Htt gene expression is considered the most promising therapeutic approach for HD. We report the identification of small molecule inhibitors of Spt5-Pol II, SPI-24 and SPI-77, which selectively lower mutant Htt mRNA and protein levels in HD cells. In the BACHD mouse model, their direct delivery to the striatum diminished mutant Htt levels, ameliorated mitochondrial dysfunction, restored BDNF expression, and improved motor and anxiety-like phenotypes. Pharmacokinetic studies revealed that these SPIs pass the blood-brain-barrier. Prolonged subcutaneous injection or oral administration to early-stage mice significantly delayed disease deterioration. SPI-24 long-term treatment had no side effects or global changes in gene expression. Thus, lowering mutant Htt levels by small molecules can be an effective therapeutic strategy for HD.
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Affiliation(s)
- Anat Bahat
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, 76100, Israel.
| | - Elad Itzhaki
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Benjamin Weiss
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Michael Tolmasov
- The Mina & Everard Goodman Faculty of Life-Sciences and The Leslie & Susan Gonda Multidisciplinary Brain Research Center Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Michael Tsoory
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Yael Kuperman
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Alexander Brandis
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Khriesto A Shurrush
- The Nancy and Stephen Grand Israel National Center for Personalized Medicine, The Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Rivka Dikstein
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, 76100, Israel.
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2
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Elghondakly A, Wu CH, Klupt S, Goodson J, Winkler WC. A NusG Specialized Paralog That Exhibits Specific, High-Affinity RNA-Binding Activity. J Mol Biol 2021; 433:167100. [PMID: 34119489 DOI: 10.1016/j.jmb.2021.167100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/17/2021] [Accepted: 06/05/2021] [Indexed: 10/21/2022]
Abstract
Bacterial NusG associates with RNA polymerase (RNAP) through its N-terminal domain, while the C-terminal domain (CTD) forms dynamic interactions with Rho, S10, NusB and NusA to affect transcription elongation. While virtually all bacteria encode for a core NusG, many also synthesize paralogs that transiently bind RNAP to alter expression of targeted genes. Yet, despite the importance of the genes they regulate, most of the subfamilies of NusG paralogs (e.g., UpxY, TaA, ActX and LoaP) have not been investigated in depth. Herein, we discover that LoaP requires a small RNA hairpin located within the 5' leader region of its targeted operons. LoaP binds the RNA element with nanomolar affinity and high specificity, in contrast to other NusG proteins, which have not been shown to exhibit RNA-binding activity. These data reveal a sequence feature that can be used to identify LoaP-regulated operons. This discovery also expands the repertoire of macromolecular interactions exhibited by the NusG CTD during transcription elongation to include an RNA ligand.
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Affiliation(s)
- Amr Elghondakly
- The University of Maryland, Department of Chemistry and Biochemistry, College Park, MD, United States
| | - Chih Hao Wu
- The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD, United States
| | - Steven Klupt
- The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD, United States
| | - Jonathan Goodson
- The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD, United States
| | - Wade C Winkler
- The University of Maryland, Department of Chemistry and Biochemistry, College Park, MD, United States; The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD, United States.
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Spt4 Promotes Pol I Processivity and Transcription Elongation. Genes (Basel) 2021; 12:genes12030413. [PMID: 33809333 PMCID: PMC8000598 DOI: 10.3390/genes12030413] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 01/25/2023] Open
Abstract
RNA polymerases (Pols) I, II, and III collectively synthesize most of the RNA in a eukaryotic cell. Transcription by Pols I, II, and III is regulated by hundreds of trans-acting factors. One such protein, Spt4, has been previously identified as a transcription factor that influences both Pols I and II. Spt4 forms a complex with Spt5, described as the Spt4/5 complex (or DSIF in mammalian cells). This complex has been shown previously to directly interact with Pol I and potentially affect transcription elongation. The previous literature identified defects in transcription by Pol I when SPT4 was deleted, but the necessary tools to characterize the mechanism of this effect were not available at the time. Here, we use a technique called Native Elongating Transcript Sequencing (NET-seq) to probe for the global occupancy of Pol I in wild-type (WT) and spt4△ Saccharomyces cerevisiae (yeast) cells at single nucleotide resolution in vivo. Analysis of NET-seq data reveals that Spt4 promotes Pol I processivity and enhances transcription elongation through regions of the ribosomal DNA that are particularly G-rich. These data suggest that Spt4/5 may directly affect transcription elongation by Pol I in vivo.
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Decker TM. Mechanisms of Transcription Elongation Factor DSIF (Spt4-Spt5). J Mol Biol 2020; 433:166657. [PMID: 32987031 DOI: 10.1016/j.jmb.2020.09.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 09/16/2020] [Accepted: 09/20/2020] [Indexed: 12/19/2022]
Abstract
The transcription elongation factor Spt5 is conserved from bacteria to humans. In eukaryotes, Spt5 forms a complex with Spt4 and regulates processive transcription elongation. Recent studies on transcription elongation suggest different mechanistic roles in yeast versus mammals. Higher eukaryotes utilize Spt4-Spt5 (DSIF) to regulate promoter-proximal pausing, a transcription-regulatory mechanism that connects initiation to productive elongation. DSIF is a versatile transcription factor and has been implicated in both gene-specific regulation and transcription through nucleosomes. Future studies will further elucidate the role of DSIF in transcriptional dynamics and disentangle its inhibitory and enhancing activities in transcription.
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Affiliation(s)
- Tim-Michael Decker
- Department of Biochemistry, University of Colorado, 3415 Colorado Ave, Boulder, CO 80303, USA.
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Tellier M, Maudlin I, Murphy S. Transcription and splicing: A two-way street. WILEY INTERDISCIPLINARY REVIEWS. RNA 2020; 11:e1593. [PMID: 32128990 DOI: 10.1002/wrna.1593] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/18/2019] [Accepted: 02/12/2020] [Indexed: 12/11/2022]
Abstract
RNA synthesis by RNA polymerase II and RNA processing are closely coupled during the transcription cycle of protein-coding genes. This coupling affords opportunities for quality control and regulation of gene expression and the effects can go in both directions. For example, polymerase speed can affect splice site selection and splicing can increase transcription and affect the chromatin landscape. Here we review the many ways that transcription and splicing influence one another, including how splicing "talks back" to transcription. We will also place the connections between transcription and splicing in the context of other RNA processing events that define the exons that will make up the final mRNA. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
- Michael Tellier
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Isabella Maudlin
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Shona Murphy
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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Bahat A, Lahav O, Plotnikov A, Leshkowitz D, Dikstein R. Targeting Spt5-Pol II by Small-Molecule Inhibitors Uncouples Distinct Activities and Reveals Additional Regulatory Roles. Mol Cell 2019; 76:617-631.e4. [PMID: 31564557 DOI: 10.1016/j.molcel.2019.08.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 06/12/2019] [Accepted: 08/26/2019] [Indexed: 12/27/2022]
Abstract
Spt5 is a conserved and essential transcription elongation factor that promotes promoter-proximal pausing, promoter escape, elongation, and mRNA processing. Spt5 plays specific roles in the transcription of inflammation and stress-induced genes and tri-nucleotide expanded-repeat genes involved in inherited neurological pathologies. Here, we report the identification of Spt5-Pol II small-molecule inhibitors (SPIs). SPIs faithfully reproduced Spt5 knockdown effects on promoter-proximal pausing, NF-κB activation, and expanded-repeat huntingtin gene transcription. Using SPIs, we identified Spt5 target genes that responded with profoundly diverse kinetics. SPIs uncovered the regulatory role of Spt5 in metabolism via GDF15, a food intake- and body weight-inhibitory hormone. SPIs further unveiled a role for Spt5 in promoting the 3' end processing of histone genes. While several SPIs affect all Spt5 functions, a few inhibit a single one, implying uncoupling and selective targeting of Spt5 activities. SPIs expand the understanding of Spt5-Pol II functions and are potential drugs against metabolic and neurodegenerative diseases.
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Affiliation(s)
- Anat Bahat
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Or Lahav
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alexander Plotnikov
- The Nancy and Stephen Grand Israel National Center for Personalized Medicine, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Dena Leshkowitz
- Bioinformatics Unit, Department of Life Sciences Core Facilities, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rivka Dikstein
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
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Promoter-proximal pausing mediated by the exon junction complex regulates splicing. Nat Commun 2019; 10:521. [PMID: 30705266 PMCID: PMC6355915 DOI: 10.1038/s41467-019-08381-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 01/04/2019] [Indexed: 02/08/2023] Open
Abstract
Promoter-proximal pausing of RNA polymerase II (Pol II) is a widespread transcriptional regulatory step across metazoans. Here we find that the nuclear exon junction complex (pre-EJC) is a critical and conserved regulator of this process. Depletion of pre-EJC subunits leads to a global decrease in Pol II pausing and to premature entry into elongation. This effect occurs, at least in part, via non-canonical recruitment of pre-EJC components at promoters. Failure to recruit the pre-EJC at promoters results in increased binding of the positive transcription elongation complex (P-TEFb) and in enhanced Pol II release. Notably, restoring pausing is sufficient to rescue exon skipping and the photoreceptor differentiation defect associated with depletion of pre-EJC components in vivo. We propose that the pre-EJC serves as an early transcriptional checkpoint to prevent premature entry into elongation, ensuring proper recruitment of RNA processing components that are necessary for exon definition.
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Kachaev ZM, Lebedeva LA, Kozlov EN, Toropygin IY, Schedl P, Shidlovskii YV. Paip2 is localized to active promoters and loaded onto nascent mRNA in Drosophila. Cell Cycle 2018; 17:1708-1720. [PMID: 29995569 DOI: 10.1080/15384101.2018.1496738] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Paip2 (Poly(A)-binding protein - interacting protein 2) is a conserved metazoan-specific protein that has been implicated in regulating the translation and stability of mRNAs. However, we have found that Paip2 is not restricted to the cytoplasm but is also found in the nucleus in Drosophila embryos, salivary glands, testes, and tissue culture cells. Nuclear Paip2 is associated with chromatin, and in chromatin immunoprecipitation experiments it maps to the promoter regions of active genes. However, this chromatin association is indirect, as it is RNA-dependent. Thus, Paip2 is one more item in the growing list of translation factors that are recruited to mRNAs co-transcriptionally.
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Affiliation(s)
- Zaur M Kachaev
- a Laboratory of Gene Expression Regulation in Development , Institute of Gene Biology, Russian Academy of Sciences , Moscow , Russia
| | - Lyubov A Lebedeva
- a Laboratory of Gene Expression Regulation in Development , Institute of Gene Biology, Russian Academy of Sciences , Moscow , Russia
| | - Eugene N Kozlov
- a Laboratory of Gene Expression Regulation in Development , Institute of Gene Biology, Russian Academy of Sciences , Moscow , Russia
| | - Ilya Y Toropygin
- d Center of Common Use "Human Proteome" , V.I. Orekhovich Research Institute of Biomedical Chemistry , Moscow , Russia
| | - Paul Schedl
- a Laboratory of Gene Expression Regulation in Development , Institute of Gene Biology, Russian Academy of Sciences , Moscow , Russia.,b Department of Molecular Biology , Princeton University , Princeton , NJ , USA
| | - Yulii V Shidlovskii
- a Laboratory of Gene Expression Regulation in Development , Institute of Gene Biology, Russian Academy of Sciences , Moscow , Russia.,c Department of Biology and General Genetics , I.M. Sechenov First Moscow State Medical University , Moscow , Russia
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Shetty A, Kallgren SP, Demel C, Maier KC, Spatt D, Alver BH, Cramer P, Park PJ, Winston F. Spt5 Plays Vital Roles in the Control of Sense and Antisense Transcription Elongation. Mol Cell 2017; 66:77-88.e5. [PMID: 28366642 DOI: 10.1016/j.molcel.2017.02.023] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 01/12/2017] [Accepted: 02/22/2017] [Indexed: 12/11/2022]
Abstract
Spt5 is an essential and conserved factor that functions in transcription and co-transcriptional processes. However, many aspects of the requirement for Spt5 in transcription are poorly understood. We have analyzed the consequences of Spt5 depletion in Schizosaccharomyces pombe using four genome-wide approaches. Our results demonstrate that Spt5 is crucial for a normal rate of RNA synthesis and distribution of RNAPII over transcription units. In the absence of Spt5, RNAPII localization changes dramatically, with reduced levels and a relative accumulation over the first ∼500 bp, suggesting that Spt5 is required for transcription past a barrier. Spt5 depletion also results in widespread antisense transcription initiating within this barrier region. Deletions of this region alter the distribution of RNAPII on the sense strand, suggesting that the barrier observed after Spt5 depletion is normally a site at which Spt5 stimulates elongation. Our results reveal a global requirement for Spt5 in transcription elongation.
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Affiliation(s)
- Ameet Shetty
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Scott P Kallgren
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Carina Demel
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Kerstin C Maier
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Dan Spatt
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Burak H Alver
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Peter J Park
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Fred Winston
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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