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Paryani F, Kwon JS, Ng CW, Jakubiak K, Madden N, Ofori K, Tang A, Lu H, Xia S, Li J, Mahajan A, Davidson SM, Basile AO, McHugh C, Vonsattel JP, Hickman R, Zody MC, Housman DE, Goldman JE, Yoo AS, Menon V, Al-Dalahmah O. Multi-omic analysis of Huntington's disease reveals a compensatory astrocyte state. Nat Commun 2024; 15:6742. [PMID: 39112488 PMCID: PMC11306246 DOI: 10.1038/s41467-024-50626-0] [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: 09/17/2023] [Accepted: 07/09/2024] [Indexed: 08/10/2024] Open
Abstract
The mechanisms underlying the selective regional vulnerability to neurodegeneration in Huntington's disease (HD) have not been fully defined. To explore the role of astrocytes in this phenomenon, we used single-nucleus and bulk RNAseq, lipidomics, HTT gene CAG repeat-length measurements, and multiplexed immunofluorescence on HD and control post-mortem brains. We identified genes that correlated with CAG repeat length, which were enriched in astrocyte genes, and lipidomic signatures that implicated poly-unsaturated fatty acids in sensitizing neurons to cell death. Because astrocytes play essential roles in lipid metabolism, we explored the heterogeneity of astrocytic states in both protoplasmic and fibrous-like (CD44+) astrocytes. Significantly, one protoplasmic astrocyte state showed high levels of metallothioneins and was correlated with the selective vulnerability of distinct striatal neuronal populations. When modeled in vitro, this state improved the viability of HD-patient-derived spiny projection neurons. Our findings uncover key roles of astrocytic states in protecting against neurodegeneration in HD.
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Affiliation(s)
- Fahad Paryani
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA
| | - Ji-Sun Kwon
- Department of Developmental Biology Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Christopher W Ng
- Massachusetts Institute of Technology, Department of Biological Engineering, Cambridge, MA, USA
| | - Kelly Jakubiak
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Nacoya Madden
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Kenneth Ofori
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Alice Tang
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Hong Lu
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Shengnan Xia
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Juncheng Li
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Aayushi Mahajan
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Shawn M Davidson
- Northwestern Feinberg School of Medicine, Northwestern University, Evanston, IL, USA
| | | | | | - Jean Paul Vonsattel
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Richard Hickman
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | | | - David E Housman
- Massachusetts Institute of Technology, Department of Biological Engineering, Cambridge, MA, USA
| | - James E Goldman
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, New York, NY, USA
| | - Andrew S Yoo
- Department of Developmental Biology Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Vilas Menon
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA.
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, New York, NY, USA.
| | - Osama Al-Dalahmah
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA.
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, New York, NY, USA.
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2
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Wang N, Zhang S, Langfelder P, Ramanathan L, Plascencia M, Gao F, Vaca R, Gu X, Deng L, Dionisio LE, Prasad BC, Vogt T, Horvath S, Aaronson JS, Rosinski J, Yang XW. Msh3 and Pms1 Set Neuronal CAG-repeat Migration Rate to Drive Selective Striatal and Cortical Pathogenesis in HD Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.09.602815. [PMID: 39026894 PMCID: PMC11257559 DOI: 10.1101/2024.07.09.602815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Modifiers of Huntington's disease (HD) include mismatch repair (MMR) genes; however, their underlying disease-altering mechanisms remain unresolved. Knockout (KO) alleles for 9 HD GWAS modifiers/MMR genes were crossed to the Q140 Huntingtin (mHtt) knock-in mice to probe such mechanisms. Four KO mice strongly ( Msh3 and Pms1 ) or moderately ( Msh2 and Mlh1 ) rescue a triad of adult-onset, striatal medium-spiny-neuron (MSN)-selective phenotypes: somatic Htt DNA CAG-repeat expansion, transcriptionopathy, and mHtt protein aggregation. Comparatively, Q140 cortex also exhibits an analogous, but later-onset, pathogenic triad that is Msh3 -dependent. Remarkably, Q140/homozygous Msh3-KO lacks visible mHtt aggregates in the brain, even at advanced ages (20-months). Moreover, Msh3 -deficiency prevents striatal synaptic marker loss, astrogliosis, and locomotor impairment in HD mice. Purified Q140 MSN nuclei exhibit highly linear age-dependent mHtt DNA repeat expansion (i.e. repeat migration), with modal-CAG increasing at +8.8 repeats/month (R 2 =0.98). This linear rate is reduced to 2.3 and 0.3 repeats/month in Q140 with Msh3 heterozygous and homozygous alleles, respectively. Our study defines somatic Htt CAG-repeat thresholds below which there are no detectable mHtt nuclear or neuropil aggregates. Mild transcriptionopathy can still occur in Q140 mice with stabilized Htt 140-CAG repeats, but the majority of transcriptomic changes are due to somatic repeat expansion. Our analysis reveals 479 genes with expression levels highly correlated with modal-CAG length in MSNs. Thus, our study mechanistically connects HD GWAS genes to selective neuronal vulnerability in HD, in which Msh3 and Pms1 set the linear rate of neuronal mHtt CAG-repeat migration to drive repeat-length dependent pathogenesis; and provides a preclinical platform for targeting these genes for HD suppression across brain regions. One Sentence Summary Msh3 and Pms1 are genetic drivers of sequential striatal and cortical pathogenesis in Q140 mice by mediating selective CAG-repeat migration in HD vulnerable neurons.
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3
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Mouro Pinto R, Murtha R, Azevedo A, Douglas C, Kovalenko M, Ulloa J, Crescenti S, Burch Z, Oliver E, Vitalo A, Mota-Silva E, Riggs MJ, Correia K, Elezi E, Demelo B, Carroll JB, Gillis T, Gusella JF, MacDonald ME, Wheeler VC. Identification of genetic modifiers of Huntington's disease somatic CAG repeat instability by in vivo CRISPR-Cas9 genome editing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.08.597823. [PMID: 38895438 PMCID: PMC11185783 DOI: 10.1101/2024.06.08.597823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Huntington's disease (HD), one of >50 inherited repeat expansion disorders (Depienne and Mandel, 2021), is a dominantly-inherited neurodegenerative disease caused by a CAG expansion in HTT (The Huntington's Disease Collaborative Research Group, 1993). Inherited CAG repeat length is the primary determinant of age of onset, with human genetic studies underscoring that the property driving disease is the CAG length-dependent propensity of the repeat to further expand in brain (Swami et al ., 2009; GeM-HD, 2015; Hensman Moss et al ., 2017; Ciosi et al ., 2019; GeM-HD, 2019; Hong et al ., 2021). Routes to slowing somatic CAG expansion therefore hold great promise for disease-modifying therapies. Several DNA repair genes, notably in the mismatch repair (MMR) pathway, modify somatic expansion in HD mouse models (Wheeler and Dion, 2021). To identify novel modifiers of somatic expansion, we have used CRISPR-Cas9 editing in HD knock-in mice to enable in vivo screening of expansion-modifier candidates at scale. This has included testing of HD onset modifier genes emerging from human genome-wide association studies (GWAS), as well as interactions between modifier genes, thereby providing new insight into pathways underlying CAG expansion and potential therapeutic targets.
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4
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Ferguson R, Goold R, Coupland L, Flower M, Tabrizi SJ. Therapeutic validation of MMR-associated genetic modifiers in a human ex vivo model of Huntington disease. Am J Hum Genet 2024; 111:1165-1183. [PMID: 38749429 PMCID: PMC11179424 DOI: 10.1016/j.ajhg.2024.04.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 06/09/2024] Open
Abstract
The pathological huntingtin (HTT) trinucleotide repeat underlying Huntington disease (HD) continues to expand throughout life. Repeat length correlates both with earlier age at onset (AaO) and faster progression, making slowing its expansion an attractive therapeutic approach. Genome-wide association studies have identified candidate variants associated with altered AaO and progression, with many found in DNA mismatch repair (MMR)-associated genes. We examine whether lowering expression of these genes affects the rate of repeat expansion in human ex vivo models using HD iPSCs and HD iPSC-derived striatal medium spiny neuron-enriched cultures. We have generated a stable CRISPR interference HD iPSC line in which we can specifically and efficiently lower gene expression from a donor carrying over 125 CAG repeats. Lowering expression of each member of the MMR complexes MutS (MSH2, MSH3, and MSH6), MutL (MLH1, PMS1, PMS2, and MLH3), and LIG1 resulted in characteristic MMR deficiencies. Reduced MSH2, MSH3, and MLH1 slowed repeat expansion to the largest degree, while lowering either PMS1, PMS2, or MLH3 slowed it to a lesser degree. These effects were recapitulated in iPSC-derived striatal cultures where MutL factor expression was lowered. CRISPRi-mediated lowering of key MMR factor expression to levels feasibly achievable by current therapeutic approaches was able to effectively slow the expansion of the HTT CAG tract. We highlight members of the MutL family as potential targets to slow pathogenic repeat expansion with the aim to delay onset and progression of HD and potentially other repeat expansion disorders exhibiting somatic instability.
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Affiliation(s)
- Ross Ferguson
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK
| | - Robert Goold
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK
| | - Lucy Coupland
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK
| | - Michael Flower
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK
| | - Sarah J Tabrizi
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK.
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5
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McLean ZL, Gao D, Correia K, Roy JCL, Shibata S, Farnum IN, Valdepenas-Mellor Z, Kovalenko M, Rapuru M, Morini E, Ruliera J, Gillis T, Lucente D, Kleinstiver BP, Lee JM, MacDonald ME, Wheeler VC, Mouro Pinto R, Gusella JF. Splice modulators target PMS1 to reduce somatic expansion of the Huntington's disease-associated CAG repeat. Nat Commun 2024; 15:3182. [PMID: 38609352 PMCID: PMC11015039 DOI: 10.1038/s41467-024-47485-0] [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: 07/24/2023] [Accepted: 03/30/2024] [Indexed: 04/14/2024] Open
Abstract
Huntington's disease (HD) is a dominant neurological disorder caused by an expanded HTT exon 1 CAG repeat that lengthens huntingtin's polyglutamine tract. Lowering mutant huntingtin has been proposed for treating HD, but genetic modifiers implicate somatic CAG repeat expansion as the driver of onset. We find that branaplam and risdiplam, small molecule splice modulators that lower huntingtin by promoting HTT pseudoexon inclusion, also decrease expansion of an unstable HTT exon 1 CAG repeat in an engineered cell model. Targeted CRISPR-Cas9 editing shows this effect is not due to huntingtin lowering, pointing instead to pseudoexon inclusion in PMS1. Homozygous but not heterozygous inactivation of PMS1 also reduces CAG repeat expansion, supporting PMS1 as a genetic modifier of HD and a potential target for therapeutic intervention. Although splice modulation provides one strategy, genome-wide transcriptomics also emphasize consideration of cell-type specific effects and polymorphic variation at both target and off-target sites.
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Affiliation(s)
- Zachariah L McLean
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Dadi Gao
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Jennie C L Roy
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
| | - Shota Shibata
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Iris N Farnum
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Zoe Valdepenas-Mellor
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Marina Kovalenko
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Manasa Rapuru
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Elisabetta Morini
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
| | - Jayla Ruliera
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Benjamin P Kleinstiver
- Center for Genomic Medicine and Department of Pathology, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Pathology, Harvard Medical School, Boston, MA, 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Marcy E MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Vanessa C Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Ricardo Mouro Pinto
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - James F Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA.
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA.
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
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6
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Tong H, Yang T, Xu S, Li X, Liu L, Zhou G, Yang S, Yin S, Li XJ, Li S. Huntington's Disease: Complex Pathogenesis and Therapeutic Strategies. Int J Mol Sci 2024; 25:3845. [PMID: 38612657 PMCID: PMC11011923 DOI: 10.3390/ijms25073845] [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: 02/19/2024] [Revised: 03/21/2024] [Accepted: 03/26/2024] [Indexed: 04/14/2024] Open
Abstract
Huntington's disease (HD) arises from the abnormal expansion of CAG repeats in the huntingtin gene (HTT), resulting in the production of the mutant huntingtin protein (mHTT) with a polyglutamine stretch in its N-terminus. The pathogenic mechanisms underlying HD are complex and not yet fully elucidated. However, mHTT forms aggregates and accumulates abnormally in neuronal nuclei and processes, leading to disruptions in multiple cellular functions. Although there is currently no effective curative treatment for HD, significant progress has been made in developing various therapeutic strategies to treat HD. In addition to drugs targeting the neuronal toxicity of mHTT, gene therapy approaches that aim to reduce the expression of the mutant HTT gene hold great promise for effective HD therapy. This review provides an overview of current HD treatments, discusses different therapeutic strategies, and aims to facilitate future therapeutic advancements in the field.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Xiao-Jiang Li
- Guangdong Key Laboratory of Non-Human Primate Research, Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, China; (H.T.); (T.Y.); (S.X.); (X.L.); (L.L.); (G.Z.); (S.Y.); (S.Y.)
| | - Shihua Li
- Guangdong Key Laboratory of Non-Human Primate Research, Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, China; (H.T.); (T.Y.); (S.X.); (X.L.); (L.L.); (G.Z.); (S.Y.); (S.Y.)
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7
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Sun X, Liu L, Wu C, Li X, Guo J, Zhang J, Guan J, Wang N, Gu L, Yang XW, Li GM. Mutant huntingtin protein induces MLH1 degradation, DNA hyperexcision, and cGAS-STING-dependent apoptosis. Proc Natl Acad Sci U S A 2024; 121:e2313652121. [PMID: 38498709 PMCID: PMC10990133 DOI: 10.1073/pnas.2313652121] [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: 08/18/2023] [Accepted: 01/27/2024] [Indexed: 03/20/2024] Open
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder caused by an expanded CAG repeat in the huntingtin (HTT) gene. The repeat-expanded HTT encodes a mutated HTT (mHTT), which is known to induce DNA double-strand breaks (DSBs), activation of the cGAS-STING pathway, and apoptosis in HD. However, the mechanism by which mHTT triggers these events is unknown. Here, we show that HTT interacts with both exonuclease 1 (Exo1) and MutLα (MLH1-PMS2), a negative regulator of Exo1. While the HTT-Exo1 interaction suppresses the Exo1-catalyzed DNA end resection during DSB repair, the HTT-MutLα interaction functions to stabilize MLH1. However, mHTT displays a significantly reduced interaction with Exo1 or MutLα, thereby losing the ability to regulate Exo1. Thus, cells expressing mHTT exhibit rapid MLH1 degradation and hyperactive DNA excision, which causes severe DNA damage and cytosolic DNA accumulation. This activates the cGAS-STING pathway to mediate apoptosis. Therefore, we have identified unique functions for both HTT and mHTT in modulating DNA repair and the cGAS-STING pathway-mediated apoptosis by interacting with MLH1. Our work elucidates the mechanism by which mHTT causes HD.
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Affiliation(s)
- Xiao Sun
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX75390
- The Ministry of Education Key Laboratory of Reproductive Genetics, Department of Reproductive Endocrinology, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou310006, China
| | - Lu Liu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Chao Wu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Xueying Li
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Jinzhen Guo
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Junqiu Zhang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Junhong Guan
- Cui-ying Experimental Center, Lanzhou University Second Hospital, Lanzhou730030, China
| | - Nan Wang
- Center for Neurobehavioral Genetics, Semel Institute for Neuroscience & Human behavior, University of California, Los Angeles, CA90095
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Liya Gu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - X. Willian Yang
- Center for Neurobehavioral Genetics, Semel Institute for Neuroscience & Human behavior, University of California, Los Angeles, CA90095
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Guo-Min Li
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Institute for Cancer Research, Chinese Institutes for Medical Research, Beijing100069, China
- School of Basic Medical Sciences, Capital Medical University, Beijing100069, China
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8
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Hong EP, Ramos EM, Aziz NA, Massey TH, McAllister B, Lobanov S, Jones L, Holmans P, Kwak S, Orth M, Ciosi M, Lomeikaite V, Monckton DG, Long JD, Lucente D, Wheeler VC, Gillis T, MacDonald ME, Sequeiros J, Gusella JF, Lee JM. Modification of Huntington's disease by short tandem repeats. Brain Commun 2024; 6:fcae016. [PMID: 38449714 PMCID: PMC10917446 DOI: 10.1093/braincomms/fcae016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 12/20/2023] [Accepted: 01/22/2024] [Indexed: 03/08/2024] Open
Abstract
Expansions of glutamine-coding CAG trinucleotide repeats cause a number of neurodegenerative diseases, including Huntington's disease and several of spinocerebellar ataxias. In general, age-at-onset of the polyglutamine diseases is inversely correlated with the size of the respective inherited expanded CAG repeat. Expanded CAG repeats are also somatically unstable in certain tissues, and age-at-onset of Huntington's disease corrected for individual HTT CAG repeat length (i.e. residual age-at-onset), is modified by repeat instability-related DNA maintenance/repair genes as demonstrated by recent genome-wide association studies. Modification of one polyglutamine disease (e.g. Huntington's disease) by the repeat length of another (e.g. ATXN3, CAG expansions in which cause spinocerebellar ataxia 3) has also been hypothesized. Consequently, we determined whether age-at-onset in Huntington's disease is modified by the CAG repeats of other polyglutamine disease genes. We found that the CAG measured repeat sizes of other polyglutamine disease genes that were polymorphic in Huntington's disease participants but did not influence Huntington's disease age-at-onset. Additional analysis focusing specifically on ATXN3 in a larger sample set (n = 1388) confirmed the lack of association between Huntington's disease residual age-at-onset and ATXN3 CAG repeat length. Additionally, neither our Huntington's disease onset modifier genome-wide association studies single nucleotide polymorphism data nor imputed short tandem repeat data supported the involvement of other polyglutamine disease genes in modifying Huntington's disease. By contrast, our genome-wide association studies based on imputed short tandem repeats revealed significant modification signals for other genomic regions. Together, our short tandem repeat genome-wide association studies show that modification of Huntington's disease is associated with short tandem repeats that do not involve other polyglutamine disease-causing genes, refining the landscape of Huntington's disease modification and highlighting the importance of rigorous data analysis, especially in genetic studies testing candidate modifiers.
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Affiliation(s)
- Eun Pyo Hong
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Eliana Marisa Ramos
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - N Ahmad Aziz
- Population & Clinical Neuroepidemiology, German Center for Neurodegenerative Diseases, 53127 Bonn, Germany
- Department of Neurology, Faculty of Medicine, University of Bonn, Bonn D-53113, Germany
| | - Thomas H Massey
- Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Branduff McAllister
- Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Sergey Lobanov
- Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Lesley Jones
- Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Peter Holmans
- Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Seung Kwak
- Molecular System Biology, CHDI Foundation, Princeton, NJ 08540, USA
| | - Michael Orth
- University Hospital of Old Age Psychiatry and Psychotherapy, Bern University, CH-3000 Bern 60, Switzerland
| | - Marc Ciosi
- School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Vilija Lomeikaite
- School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Darren G Monckton
- School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Jeffrey D Long
- Department of Psychiatry, Carver College of Medicine and Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA 52242, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Vanessa C Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Marcy E MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Jorge Sequeiros
- UnIGENe, IBMC—Institute for Molecular and Cell Biology, i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 420-135, Portugal
- ICBAS School of Medicine and Biomedical Sciences, University of Porto, Porto 420-135, Portugal
| | - James F Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
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9
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Handley RR, Reid SJ, Burch Z, Jacobsen JC, Gillis T, Correia K, Rudiger SR, McLaughlin CJ, Bawden CS, MacDonald ME, Wheeler VC, Snell RG. Somatic CAG Repeat Stability in a Transgenic Sheep Model of Huntington's Disease. J Huntingtons Dis 2024; 13:33-40. [PMID: 38393920 DOI: 10.3233/jhd-231516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
Somatic instability of the huntingtin (HTT) CAG repeat mutation modifies age-at-onset of Huntington's disease (HD). Understanding the mechanism and pathogenic consequences of instability may reveal therapeutic targets. Using small-pool PCR we analyzed CAG instability in the OVT73 sheep model which expresses a full-length human cDNA HTT transgene. Analyses of five- and ten-year old sheep revealed the transgene (CAG)69 repeat was remarkably stable in liver, striatum, and other brain tissues. As OVT73 sheep at ten years old have minimal cell death and behavioral changes, our findings support instability of the HTT expanded-CAG repeat as being required for the progression of HD.
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Affiliation(s)
- Renee R Handley
- Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Suzanne J Reid
- Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Zoe Burch
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Jessie C Jacobsen
- Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Tammy Gillis
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Kevin Correia
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Skye R Rudiger
- Molecular Biology and Reproductive Technology, Laboratories, South Australian Research and Development Institute, Adelaide, SA, Australia
| | - Clive J McLaughlin
- Molecular Biology and Reproductive Technology, Laboratories, South Australian Research and Development Institute, Adelaide, SA, Australia
| | - C Simon Bawden
- Molecular Biology and Reproductive Technology, Laboratories, South Australian Research and Development Institute, Adelaide, SA, Australia
| | - Marcy E MacDonald
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Vanessa C Wheeler
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Russell G Snell
- Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
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10
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Rajagopal S, Donaldson J, Flower M, Hensman Moss DJ, Tabrizi SJ. Genetic modifiers of repeat expansion disorders. Emerg Top Life Sci 2023; 7:325-337. [PMID: 37861103 PMCID: PMC10754329 DOI: 10.1042/etls20230015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 09/20/2023] [Accepted: 10/09/2023] [Indexed: 10/21/2023]
Abstract
Repeat expansion disorders (REDs) are monogenic diseases caused by a sequence of repetitive DNA expanding above a pathogenic threshold. A common feature of the REDs is a strong genotype-phenotype correlation in which a major determinant of age at onset (AAO) and disease progression is the length of the inherited repeat tract. Over a disease-gene carrier's life, the length of the repeat can expand in somatic cells, through the process of somatic expansion which is hypothesised to drive disease progression. Despite being monogenic, individual REDs are phenotypically variable, and exploring what genetic modifying factors drive this phenotypic variability has illuminated key pathogenic mechanisms that are common to this group of diseases. Disease phenotypes are affected by the cognate gene in which the expansion is found, the location of the repeat sequence in coding or non-coding regions and by the presence of repeat sequence interruptions. Human genetic data, mouse models and in vitro models have implicated the disease-modifying effect of DNA repair pathways via the mechanisms of somatic mutation of the repeat tract. As such, developing an understanding of these pathways in the context of expanded repeats could lead to future disease-modifying therapies for REDs.
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Affiliation(s)
- Sangeerthana Rajagopal
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
| | - Jasmine Donaldson
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
| | - Michael Flower
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
| | - Davina J Hensman Moss
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
- St George's University of London, London SW17 0RE, U.K
| | - Sarah J Tabrizi
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
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11
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Medina-Rivera M, Phelps S, Sridharan M, Becker J, Lamb N, Kumar C, Sutton M, Bielinsky A, Balakrishnan L, Surtees J. Elevated MSH2 MSH3 expression interferes with DNA metabolism in vivo. Nucleic Acids Res 2023; 51:12185-12206. [PMID: 37930834 PMCID: PMC10711559 DOI: 10.1093/nar/gkad934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/30/2023] [Accepted: 10/10/2023] [Indexed: 11/08/2023] Open
Abstract
The Msh2-Msh3 mismatch repair (MMR) complex in Saccharomyces cerevisiae recognizes and directs repair of insertion/deletion loops (IDLs) up to ∼17 nucleotides. Msh2-Msh3 also recognizes and binds distinct looped and branched DNA structures with varying affinities, thereby contributing to genome stability outside post-replicative MMR through homologous recombination, double-strand break repair (DSBR) and the DNA damage response. In contrast, Msh2-Msh3 promotes genome instability through trinucleotide repeat (TNR) expansions, presumably by binding structures that form from single-stranded (ss) TNR sequences. We previously demonstrated that Msh2-Msh3 binding to 5' ssDNA flap structures interfered with Rad27 (Fen1 in humans)-mediated Okazaki fragment maturation (OFM) in vitro. Here we demonstrate that elevated Msh2-Msh3 levels interfere with DNA replication and base excision repair in vivo. Elevated Msh2-Msh3 also induced a cell cycle arrest that was dependent on RAD9 and ELG1 and led to PCNA modification. These phenotypes also required Msh2-Msh3 ATPase activity and downstream MMR proteins, indicating an active mechanism that is not simply a result of Msh2-Msh3 DNA-binding activity. This study provides new mechanistic details regarding how excess Msh2-Msh3 can disrupt DNA replication and repair and highlights the role of Msh2-Msh3 protein abundance in Msh2-Msh3-mediated genomic instability.
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Affiliation(s)
- Melisa Medina-Rivera
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Samantha Phelps
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Madhumita Sridharan
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Jordan Becker
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Natalie A Lamb
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Charanya Kumar
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Mark D Sutton
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
| | - Anja Bielinsky
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Lata Balakrishnan
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Jennifer A Surtees
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY, 14203, USA
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12
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Gall-Duncan T, Luo J, Jurkovic CM, Fischer LA, Fujita K, Deshmukh AL, Harding RJ, Tran S, Mehkary M, Li V, Leib DE, Chen R, Tanaka H, Mason AG, Lévesque D, Khan M, Razzaghi M, Prasolava T, Lanni S, Sato N, Caron MC, Panigrahi GB, Wang P, Lau R, Castel AL, Masson JY, Tippett L, Turner C, Spies M, La Spada AR, Campos EI, Curtis MA, Boisvert FM, Faull RLM, Davidson BL, Nakamori M, Okazawa H, Wold MS, Pearson CE. Antagonistic roles of canonical and Alternative-RPA in disease-associated tandem CAG repeat instability. Cell 2023; 186:4898-4919.e25. [PMID: 37827155 PMCID: PMC11209935 DOI: 10.1016/j.cell.2023.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 06/30/2023] [Accepted: 09/09/2023] [Indexed: 10/14/2023]
Abstract
Expansions of repeat DNA tracts cause >70 diseases, and ongoing expansions in brains exacerbate disease. During expansion mutations, single-stranded DNAs (ssDNAs) form slipped-DNAs. We find the ssDNA-binding complexes canonical replication protein A (RPA1, RPA2, and RPA3) and Alternative-RPA (RPA1, RPA3, and primate-specific RPA4) are upregulated in Huntington disease and spinocerebellar ataxia type 1 (SCA1) patient brains. Protein interactomes of RPA and Alt-RPA reveal unique and shared partners, including modifiers of CAG instability and disease presentation. RPA enhances in vitro melting, FAN1 excision, and repair of slipped-CAGs and protects against CAG expansions in human cells. RPA overexpression in SCA1 mouse brains ablates expansions, coincident with decreased ATXN1 aggregation, reduced brain DNA damage, improved neuron morphology, and rescued motor phenotypes. In contrast, Alt-RPA inhibits melting, FAN1 excision, and repair of slipped-CAGs and promotes CAG expansions. These findings suggest a functional interplay between the two RPAs where Alt-RPA may antagonistically offset RPA's suppression of disease-associated repeat expansions, which may extend to other DNA processes.
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Affiliation(s)
- Terence Gall-Duncan
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Jennifer Luo
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | | | - Laura A Fischer
- Developmental Biology and Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Kyota Fujita
- Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Amit L Deshmukh
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Rachel J Harding
- Structural Genomics Consortium, University of Toronto, Toronto, ON M5G 1L7, Canada; Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Stephanie Tran
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Mustafa Mehkary
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Vanessa Li
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - David E Leib
- Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19146, USA
| | - Ran Chen
- Pediatrics, Division of Hematology and Oncology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hikari Tanaka
- Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Amanda G Mason
- Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Dominique Lévesque
- Immunology and Cell Biology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Mahreen Khan
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Mortezaali Razzaghi
- Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Tanya Prasolava
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Stella Lanni
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Nozomu Sato
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Marie-Christine Caron
- CHU de Québec-Université Laval, Oncology Division, Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec, QC, Canada
| | - Gagan B Panigrahi
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Peixiang Wang
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Rachel Lau
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | | | - Jean-Yves Masson
- CHU de Québec-Université Laval, Oncology Division, Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec, QC, Canada
| | - Lynette Tippett
- School of Psychology, University of Auckland, Auckland, New Zealand; University Research Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Clinton Turner
- Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Maria Spies
- Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Albert R La Spada
- Pathology & Laboratory Medicine, Neurology, and Biological Chemistry, University of California, Irvine School of Medicine, Irvine, CA, USA; Neurobiology & Behavior, University of California, Irvine, Irvine, CA, USA; Center for Neurotherapeutics, University of California, Irvine, Irvine, CA 92697, USA
| | - Eric I Campos
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Maurice A Curtis
- University Research Centre for Brain Research, University of Auckland, Auckland, New Zealand; Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | | | - Richard L M Faull
- University Research Centre for Brain Research, University of Auckland, Auckland, New Zealand; Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | - Beverly L Davidson
- Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19146, USA
| | - Masayuki Nakamori
- Neurology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hitoshi Okazawa
- Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Marc S Wold
- Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Christopher E Pearson
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Structural Genomics Consortium, University of Toronto, Toronto, ON M5G 1L7, Canada.
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13
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Paryani F, Kwon JS, Ng CW, Madden N, Ofori K, Tang A, Lu H, Li J, Mahajan A, Davidson SM, Basile A, McHugh C, Vonsattel JP, Hickman R, Zody M, Houseman DE, Goldman JE, Yoo AS, Menon V, Al-Dalahmah O. Multi-OMIC analysis of Huntington disease reveals a neuroprotective astrocyte state. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.08.556867. [PMID: 37745577 PMCID: PMC10515780 DOI: 10.1101/2023.09.08.556867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Huntington disease (HD) is an incurable neurodegenerative disease characterized by neuronal loss and astrogliosis. One hallmark of HD is the selective neuronal vulnerability of striatal medium spiny neurons. To date, the underlying mechanisms of this selective vulnerability have not been fully defined. Here, we employed a multi-omic approach including single nucleus RNAseq (snRNAseq), bulk RNAseq, lipidomics, HTT gene CAG repeat length measurements, and multiplexed immunofluorescence on post-mortem brain tissue from multiple brain regions of HD and control donors. We defined a signature of genes that is driven by CAG repeat length and found it enriched in astrocytic and microglial genes. Moreover, weighted gene correlation network analysis showed loss of connectivity of astrocytic and microglial modules in HD and identified modules that correlated with CAG-repeat length which further implicated inflammatory pathways and metabolism. We performed lipidomic analysis of HD and control brains and identified several lipid species that correlate with HD grade, including ceramides and very long chain fatty acids. Integration of lipidomics and bulk transcriptomics identified a consensus gene signature that correlates with HD grade and HD lipidomic abnormalities and implicated the unfolded protein response pathway. Because astrocytes are critical for brain lipid metabolism and play important roles in regulating inflammation, we analyzed our snRNAseq dataset with an emphasis on astrocyte pathology. We found two main astrocyte types that spanned multiple brain regions; these types correspond to protoplasmic astrocytes, and fibrous-like - CD44-positive, astrocytes. HD pathology was differentially associated with these cell types in a region-specific manner. One protoplasmic astrocyte cluster showed high expression of metallothionein genes, the depletion of this cluster positively correlated with the depletion of vulnerable medium spiny neurons in the caudate nucleus. We confirmed that metallothioneins were increased in cingulate HD astrocytes but were unchanged or even decreased in caudate astrocytes. We combined existing genome-wide association studies (GWAS) with a GWA study conducted on HD patients from the original Venezuelan cohort and identified a single-nucleotide polymorphism in the metallothionein gene locus associated with delayed age of onset. Functional studies found that metallothionein overexpressing astrocytes are better able to buffer glutamate and were neuroprotective of patient-derived directly reprogrammed HD MSNs as well as against rotenone-induced neuronal death in vitro. Finally, we found that metallothionein-overexpressing astrocytes increased the phagocytic activity of microglia in vitro and increased the expression of genes involved in fatty acid binding. Together, we identified an astrocytic phenotype that is regionally-enriched in less vulnerable brain regions that can be leveraged to protect neurons in HD.
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Affiliation(s)
- Fahad Paryani
- Department of Neurology, Columbia University Irving Medical Center
| | - Ji-Sun Kwon
- Washington University School of Medicine in St. Louis
| | - Chris W Ng
- Massachusetts Institute of Technology, Department of Biological Engineering
| | - Nacoya Madden
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | - Kenneth Ofori
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | - Alice Tang
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | - Hong Lu
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | - Juncheng Li
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | - Aayushi Mahajan
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | - Shawn M. Davidson
- Princeton University, Lewis-Sigler Institute for Integrative Genomics
| | | | | | - Jean Paul Vonsattel
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | - Richard Hickman
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | | | - David E. Houseman
- Massachusetts Institute of Technology, Department of Biological Engineering
| | - James E. Goldman
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
| | - Andrew S. Yoo
- Washington University School of Medicine in St. Louis
| | - Vilas Menon
- Department of Neurology, Columbia University Irving Medical Center
| | - Osama Al-Dalahmah
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center
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14
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Phadte AS, Bhatia M, Ebert H, Abdullah H, Elrazaq EA, Komolov KE, Pluciennik A. FAN1 removes triplet repeat extrusions via a PCNA- and RFC-dependent mechanism. Proc Natl Acad Sci U S A 2023; 120:e2302103120. [PMID: 37549289 PMCID: PMC10438374 DOI: 10.1073/pnas.2302103120] [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: 02/06/2023] [Accepted: 06/22/2023] [Indexed: 08/09/2023] Open
Abstract
Human genome-wide association studies have identified FAN1 and several DNA mismatch repair (MMR) genes as modifiers of Huntington's disease age of onset. In animal models, FAN1 prevents somatic expansion of CAG triplet repeats, whereas MMR proteins promote this process. To understand the molecular basis of these opposing effects, we evaluated FAN1 nuclease function on DNA extrahelical extrusions that represent key intermediates in triplet repeat expansion. Here, we describe a strand-directed, extrusion-provoked nuclease function of FAN1 that is activated by RFC, PCNA, and ATP at physiological ionic strength. Activation of FAN1 in this manner results in DNA cleavage in the vicinity of triplet repeat extrahelical extrusions thereby leading to their removal in human cell extracts. The role of PCNA and RFC is to confer strand directionality to the FAN1 nuclease, and this reaction requires a physical interaction between PCNA and FAN1. Using cell extracts, we show that FAN1-dependent CAG extrusion removal relies on a very short patch excision-repair mechanism that competes with MutSβ-dependent MMR which is characterized by longer excision tracts. These results provide a mechanistic basis for the role of FAN1 in preventing repeat expansion and could explain the antagonistic effects of MMR and FAN1 in disease onset/progression.
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Affiliation(s)
- Ashutosh S. Phadte
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Mayuri Bhatia
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Hope Ebert
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Haaris Abdullah
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Essam Abed Elrazaq
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Konstantin E. Komolov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Anna Pluciennik
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
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15
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McLean ZL, Gao D, Correia K, Roy JCL, Shibata S, Farnum IN, Valdepenas-Mellor Z, Rapuru M, Morini E, Ruliera J, Gillis T, Lucente D, Kleinstiver BP, Lee JM, MacDonald ME, Wheeler VC, Pinto RM, Gusella JF. PMS1 as a target for splice modulation to prevent somatic CAG repeat expansion in Huntington's disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550489. [PMID: 37547003 PMCID: PMC10402039 DOI: 10.1101/2023.07.25.550489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder whose motor, cognitive, and behavioral manifestations are caused by an expanded, somatically unstable CAG repeat in the first exon of HTT that lengthens a polyglutamine tract in huntingtin. Genome-wide association studies (GWAS) have revealed DNA repair genes that influence the age-at-onset of HD and implicate somatic CAG repeat expansion as the primary driver of disease timing. To prevent the consequent neuronal damage, small molecule splice modulators (e.g., branaplam) that target HTT to reduce the levels of huntingtin are being investigated as potential HD therapeutics. We found that the effectiveness of the splice modulators can be influenced by genetic variants, both at HTT and other genes where they promote pseudoexon inclusion. Surprisingly, in a novel hTERT-immortalized retinal pigment epithelial cell (RPE1) model for assessing CAG repeat instability, these drugs also reduced the rate of HTT CAG expansion. We determined that the splice modulators also affect the expression of the mismatch repair gene PMS1, a known modifier of HD age-at-onset. Genome editing at specific HTT and PMS1 sequences using CRISPR-Cas9 nuclease confirmed that branaplam suppresses CAG expansion by promoting the inclusion of a pseudoexon in PMS1, making splice modulation of PMS1 a potential strategy for delaying HD onset. Comparison with another splice modulator, risdiplam, suggests that other genes affected by these splice modulators also influence CAG instability and might provide additional therapeutic targets.
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Affiliation(s)
- Zachariah L. McLean
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Dadi Gao
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jennie C. L. Roy
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Shota Shibata
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Iris N. Farnum
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Zoe Valdepenas-Mellor
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Manasa Rapuru
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Elisabetta Morini
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Jayla Ruliera
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Benjamin P. Kleinstiver
- Center for Genomic Medicine and Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Marcy E. MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Vanessa C. Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Ricardo Mouro Pinto
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - James F. Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
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16
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O'Reilly D, Belgrad J, Ferguson C, Summers A, Sapp E, McHugh C, Mathews E, Boudi A, Buchwald J, Ly S, Moreno D, Furgal R, Luu E, Kennedy Z, Hariharan V, Monopoli K, Yang XW, Carroll J, DiFiglia M, Aronin N, Khvorova A. Di-valent siRNA-mediated silencing of MSH3 blocks somatic repeat expansion in mouse models of Huntington's disease. Mol Ther 2023; 31:1661-1674. [PMID: 37177784 PMCID: PMC10277892 DOI: 10.1016/j.ymthe.2023.05.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 03/10/2023] [Accepted: 05/08/2023] [Indexed: 05/15/2023] Open
Abstract
Huntington's disease (HD) is a severe neurodegenerative disorder caused by the expansion of the CAG trinucleotide repeat tract in the huntingtin gene. Inheritance of expanded CAG repeats is needed for HD manifestation, but further somatic expansion of the repeat tract in non-dividing cells, particularly striatal neurons, hastens disease onset. Called somatic repeat expansion, this process is mediated by the mismatch repair (MMR) pathway. Among MMR components identified as modifiers of HD onset, MutS homolog 3 (MSH3) has emerged as a potentially safe and effective target for therapeutic intervention. Here, we identify a fully chemically modified short interfering RNA (siRNA) that robustly silences Msh3 in vitro and in vivo. When synthesized in a di-valent scaffold, siRNA-mediated silencing of Msh3 effectively blocked CAG-repeat expansion in the striatum of two HD mouse models without affecting tumor-associated microsatellite instability or mRNA expression of other MMR genes. Our findings establish a promising treatment approach for patients with HD and other repeat expansion diseases.
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Affiliation(s)
- Daniel O'Reilly
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Jillian Belgrad
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Chantal Ferguson
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Ashley Summers
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Ellen Sapp
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Cassandra McHugh
- Behavioral Neuroscience Program, Psychology Department, Western Washington University, Bellingham, WA 98225, USA
| | - Ella Mathews
- Behavioral Neuroscience Program, Psychology Department, Western Washington University, Bellingham, WA 98225, USA
| | - Adel Boudi
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Julianna Buchwald
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Socheata Ly
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Dimas Moreno
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Raymond Furgal
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Eric Luu
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Zachary Kennedy
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Vignesh Hariharan
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Kathryn Monopoli
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - X William Yang
- Center for Neurobehavioral Genetics, Jane and Terry Semel Institute of Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA 90095, USA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Jeffery Carroll
- Behavioral Neuroscience Program, Psychology Department, Western Washington University, Bellingham, WA 98225, USA; Department of Neurology, University of Washington, Seattle, WA 98104-2499, USA
| | - Marian DiFiglia
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Neil Aronin
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Anastasia Khvorova
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA.
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17
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Masnovo C, Lobo AF, Mirkin SM. Replication dependent and independent mechanisms of GAA repeat instability. DNA Repair (Amst) 2022; 118:103385. [PMID: 35952488 PMCID: PMC9675320 DOI: 10.1016/j.dnarep.2022.103385] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/28/2022] [Accepted: 07/30/2022] [Indexed: 11/20/2022]
Abstract
Trinucleotide repeat instability is a driver of human disease. Large expansions of (GAA)n repeats in the first intron of the FXN gene are the cause Friedreich's ataxia (FRDA), a progressive degenerative disorder which cannot yet be prevented or treated. (GAA)n repeat instability arises during both replication-dependent processes, such as cell division and intergenerational transmission, as well as in terminally differentiated somatic tissues. Here, we provide a brief historical overview on the discovery of (GAA)n repeat expansions and their association to FRDA, followed by recent advances in the identification of triplex H-DNA formation and replication fork stalling. The main body of this review focuses on the last decade of progress in understanding the mechanism of (GAA)n repeat instability during DNA replication and/or DNA repair. We propose that the discovery of additional mechanisms of (GAA)n repeat instability can be achieved via both comparative approaches to other repeat expansion diseases and genome-wide association studies. Finally, we discuss the advances towards FRDA prevention or amelioration that specifically target (GAA)n repeat expansions.
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Affiliation(s)
- Chiara Masnovo
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Ayesha F Lobo
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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18
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Abstract
Roughly 3% of the human genome consists of microsatellites or tracts of short tandem repeats (STRs). These STRs are often unstable, undergoing high-frequency expansions (increases) or contractions (decreases) in the number of repeat units. Some microsatellite instability (MSI) is seen at multiple STRs within a single cell and is associated with certain types of cancer. A second form of MSI is characterised by expansion of a single gene-specific STR and such expansions are responsible for a group of 40+ human genetic disorders known as the repeat expansion diseases (REDs). While the mismatch repair (MMR) pathway prevents genome-wide MSI, emerging evidence suggests that some MMR factors are directly involved in generating expansions in the REDs. Thus, MMR suppresses some forms of expansion while some MMR factors promote expansion in other contexts. This review will cover what is known about the paradoxical effect of MMR on microsatellite expansion in mammalian cells.
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19
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Wipf P, Polyzos AA, McMurray CT. A Double-Pronged Sword: XJB-5-131 Is a Suppressor of Somatic Instability and Toxicity in Huntington's Disease. J Huntingtons Dis 2022; 11:3-15. [PMID: 34924397 PMCID: PMC9028625 DOI: 10.3233/jhd-210510] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Due to large increases in the elderly populations across the world, age-related diseases are expected to expand dramatically in the coming years. Among these, neurodegenerative diseases will be among the most devastating in terms of their emotional and economic impact on patients, their families, and associated subsidized health costs. There is no currently available cure or rescue for dying brain cells. Viable therapeutics for any of these disorders would be a breakthrough and provide relief for the large number of affected patients and their families. Neurodegeneration is accompanied by elevated oxidative damage and inflammation. While natural antioxidants have largely failed in clinical trials, preclinical phenotyping of the unnatural, mitochondrial targeted nitroxide, XJB-5-131, bodes well for further translational development in advanced animal models or in humans. Here we consider the usefulness of synthetic antioxidants for the treatment of Huntington's disease. The mitochondrial targeting properties of XJB-5-131 have great promise. It is both an electron scavenger and an antioxidant, reducing both somatic expansion and toxicity simultaneously through the same redox mechanism. By quenching reactive oxygen species, XJB-5-131 breaks the cycle between the rise in oxidative damage during disease progression and the somatic growth of the CAG repeat which depends on oxidation.
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Affiliation(s)
- Pater Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Aris A. Polyzos
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Cynthia T. McMurray
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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20
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Sanchez A, Reginato G, Cejka P. Crossover or non-crossover outcomes: tailored processing of homologous recombination intermediates. Curr Opin Genet Dev 2021; 71:39-47. [PMID: 34293660 DOI: 10.1016/j.gde.2021.06.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 06/15/2021] [Accepted: 06/23/2021] [Indexed: 12/14/2022]
Abstract
DNA breaks may arise accidentally in vegetative cells or in a programmed manner in meiosis. The usage of a DNA template makes homologous recombination potentially error-free, however, recombination is not always accurate. Cells possess a remarkable capacity to tailor processing of recombination intermediates to fulfill a particular need. Vegetatively growing cells aim to maintain genome stability and therefore repair accidental breaks largely accurately, using sister chromatids as templates, into mostly non-crossovers products. Recombination in meiotic cells is instead more likely to employ homologous chromosomes as templates and result in crossovers to allow proper chromosome segregation and promote genetic diversity. Here we review models explaining the processing of recombination intermediates in vegetative and meiotic cells and its regulation, with a focus on MLH1-MLH3-dependent crossing-over during meiotic recombination.
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Affiliation(s)
- Aurore Sanchez
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland
| | - Giordano Reginato
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland.
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