1
|
Giannini M, Porrua O. Senataxin: A key actor in RNA metabolism, genome integrity and neurodegeneration. Biochimie 2024; 217:10-19. [PMID: 37558082 DOI: 10.1016/j.biochi.2023.08.001] [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: 05/08/2023] [Revised: 07/29/2023] [Accepted: 08/01/2023] [Indexed: 08/11/2023]
Abstract
The RNA/DNA helicase senataxin (SETX) has been involved in multiple crucial processes related to genome expression and integrity such us transcription termination, the regulation of transcription-replication conflicts and the resolution of R-loops. SETX has been the focus of numerous studies since the discovery that mutations in its coding gene are the root cause of two different neurodegenerative diseases: Ataxia with Oculomotor Apraxia type 2 (AOA2) and a juvenile form of Amyotrophic Lateral Sclerosis (ALS4). A plethora of cellular phenotypes have been described as the result of SETX deficiency, yet the precise molecular function of SETX as well as the molecular pathways leading from SETX mutations to AOA2 and ALS4 pathologies have remained unclear. However, recent data have shed light onto the biochemical activities and biological roles of SETX, thus providing new clues to understand the molecular consequences of SETX mutation. In this review we summarize near two decades of scientific effort to elucidate SETX function, we discuss strengths and limitations of the approaches and models used thus far to investigate SETX-associated diseases and suggest new possible research avenues for the study of AOA2 and ALS4 pathogenesis.
Collapse
Affiliation(s)
- Marta Giannini
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
| | - Odil Porrua
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France.
| |
Collapse
|
2
|
Gambelli A, Ferrando A, Boncristiani C, Schoeftner S. Regulation and function of R-loops at repetitive elements. Biochimie 2023; 214:141-155. [PMID: 37619810 DOI: 10.1016/j.biochi.2023.08.013] [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: 05/05/2023] [Revised: 08/13/2023] [Accepted: 08/19/2023] [Indexed: 08/26/2023]
Abstract
R-loops are atypical, three-stranded nucleic acid structures that contain a stretch of RNA:DNA hybrids and an unpaired, single stranded DNA loop. R-loops are physiological relevant and can act as regulators of gene expression, chromatin structure, DNA damage repair and DNA replication. However, unscheduled and persistent R-loops are mutagenic and can mediate replication-transcription conflicts, leading to DNA damage and genome instability if left unchecked. Detailed transcriptome analysis unveiled that 85% of the human genome, including repetitive regions, hold transcriptional activity. This anticipates that R-loops management plays a central role for the regulation and integrity of genomes. This function is expected to have a particular relevance for repetitive sequences that make up to 75% of the human genome. Here, we review the impact of R-loops on the function and stability of repetitive regions such as centromeres, telomeres, rDNA arrays, transposable elements and triplet repeat expansions and discuss their relevance for associated pathological conditions.
Collapse
Affiliation(s)
- Alice Gambelli
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Alessandro Ferrando
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Chiara Boncristiani
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Stefan Schoeftner
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy.
| |
Collapse
|
3
|
Salvato I, Ricciardi L, Dal Col J, Nigro A, Giurato G, Memoli D, Sellitto A, Lamparelli EP, Crescenzi MA, Vitale M, Vatrella A, Nucera F, Brun P, Caicci F, Dama P, Stiff T, Castellano L, Idrees S, Johansen MD, Faiz A, Wark PA, Hansbro PM, Adcock IM, Caramori G, Stellato C. Expression of targets of the RNA-binding protein AUF-1 in human airway epithelium indicates its role in cellular senescence and inflammation. Front Immunol 2023; 14:1192028. [PMID: 37483631 PMCID: PMC10360199 DOI: 10.3389/fimmu.2023.1192028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 06/06/2023] [Indexed: 07/25/2023] Open
Abstract
Introduction The RNA-binding protein AU-rich-element factor-1 (AUF-1) participates to posttranscriptional regulation of genes involved in inflammation and cellular senescence, two pathogenic mechanisms of chronic obstructive pulmonary disease (COPD). Decreased AUF-1 expression was described in bronchiolar epithelium of COPD patients versus controls and in vitro cytokine- and cigarette smoke-challenged human airway epithelial cells, prompting the identification of epithelial AUF-1-targeted transcripts and function, and investigation on the mechanism of its loss. Results RNA immunoprecipitation-sequencing (RIP-Seq) identified, in the human airway epithelial cell line BEAS-2B, 494 AUF-1-bound mRNAs enriched in their 3'-untranslated regions for a Guanine-Cytosine (GC)-rich binding motif. AUF-1 association with selected transcripts and with a synthetic GC-rich motif were validated by biotin pulldown. AUF-1-targets' steady-state levels were equally affected by partial or near-total AUF-1 loss induced by cytomix (TNFα/IL1β/IFNγ/10 nM each) and siRNA, respectively, with differential transcript decay rates. Cytomix-mediated decrease in AUF-1 levels in BEAS-2B and primary human small-airways epithelium (HSAEC) was replicated by treatment with the senescence- inducer compound etoposide and associated with readouts of cell-cycle arrest, increase in lysosomal damage and senescence-associated secretory phenotype (SASP) factors, and with AUF-1 transfer in extracellular vesicles, detected by transmission electron microscopy and immunoblotting. Extensive in-silico and genome ontology analysis found, consistent with AUF-1 functions, enriched RIP-Seq-derived AUF-1-targets in COPD-related pathways involved in inflammation, senescence, gene regulation and also in the public SASP proteome atlas; AUF-1 target signature was also significantly represented in multiple transcriptomic COPD databases generated from primary HSAEC, from lung tissue and from single-cell RNA-sequencing, displaying a predominant downregulation of expression. Discussion Loss of intracellular AUF-1 may alter posttranscriptional regulation of targets particularly relevant for protection of genomic integrity and gene regulation, thus concurring to airway epithelial inflammatory responses related to oxidative stress and accelerated aging. Exosomal-associated AUF-1 may in turn preserve bound RNA targets and sustain their function, participating to spreading of inflammation and senescence to neighbouring cells.
Collapse
Affiliation(s)
- Ilaria Salvato
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
- Respiratory Medicine Unit, Department of Biomedical Sciences, Dentistry and Morphological and Functional Imaging (BIOMORF), University of Messina, Messina, Italy
| | - Luca Ricciardi
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
- Respiratory Medicine Unit, Department of Biomedical Sciences, Dentistry and Morphological and Functional Imaging (BIOMORF), University of Messina, Messina, Italy
| | - Jessica Dal Col
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Annunziata Nigro
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Giorgio Giurato
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Domenico Memoli
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Assunta Sellitto
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Erwin Pavel Lamparelli
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Maria Assunta Crescenzi
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Monica Vitale
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Alessandro Vatrella
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| | - Francesco Nucera
- Respiratory Medicine Unit, Department of Biomedical Sciences, Dentistry and Morphological and Functional Imaging (BIOMORF), University of Messina, Messina, Italy
| | - Paola Brun
- Department of Molecular Medicine, University of Padua, Padua, Italy
| | | | - Paola Dama
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Thomas Stiff
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Leandro Castellano
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Sobia Idrees
- Centre for Inflammation, Centenary Institute and University of Technology Sydney, Faculty of Science, School of Life Sciences, Sydney, NSW, Australia
| | - Matt D. Johansen
- Centre for Inflammation, Centenary Institute and University of Technology Sydney, Faculty of Science, School of Life Sciences, Sydney, NSW, Australia
| | - Alen Faiz
- Centre for Inflammation, Centenary Institute and University of Technology Sydney, Faculty of Science, School of Life Sciences, Sydney, NSW, Australia
| | - Peter A. Wark
- Immune Health, Hunter Medical Research Institute and The University of Newcastle, Newcastle, NSW, Australia
| | - Philip M. Hansbro
- Centre for Inflammation, Centenary Institute and University of Technology Sydney, Faculty of Science, School of Life Sciences, Sydney, NSW, Australia
- Immune Health, Hunter Medical Research Institute and The University of Newcastle, Newcastle, NSW, Australia
| | - Ian M. Adcock
- National Heart and Lung Institute, Imperial College London and the National Institute for Health and Care Research (NIHR) Imperial Biomedical Research Centre, London, United Kingdom
| | - Gaetano Caramori
- Respiratory Medicine Unit, Department of Biomedical Sciences, Dentistry and Morphological and Functional Imaging (BIOMORF), University of Messina, Messina, Italy
| | - Cristiana Stellato
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy
| |
Collapse
|
4
|
Reiss M, Keegan J, Aldrich A, Lyons SM, Flynn RL. The exoribonuclease XRN2 mediates degradation of the long non-coding telomeric RNA TERRA. FEBS Lett 2023; 597:1818-1836. [PMID: 37191774 PMCID: PMC10524182 DOI: 10.1002/1873-3468.14639] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/01/2023] [Accepted: 05/05/2023] [Indexed: 05/17/2023]
Abstract
The telomeric repeat-containing RNA, TERRA, associates with both telomeric DNA and telomeric proteins, often forming RNA:DNA hybrids (R-loops). TERRA is most abundant in cancer cells utilizing the alternative lengthening of telomeres (ALT) pathway for telomere maintenance, suggesting that persistent TERRA R-loops may contribute to activation of the ALT mechanism. Therefore, we sought to identify the enzyme(s) that regulate TERRA metabolism in mammalian cells. Here, we identify that the 5'-3' exoribonuclease XRN2 regulates the stability of TERRA RNA. Moreover, while stabilization of TERRA alone was insufficient to drive ALT, depletion of XRN2 in ALT-positive cells led to a significant increase in TERRA R-loops and exacerbated ALT activity. Together, our findings highlight XRN2 as a key determinant of TERRA metabolism and telomere stability in cancer cells that rely on the ALT pathway.
Collapse
Affiliation(s)
- Matthew Reiss
- Departments of Pharmacology and Experimental Therapeutics, and Medicine, Cancer Center, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Joshua Keegan
- Departments of Pharmacology and Experimental Therapeutics, and Medicine, Cancer Center, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Anne Aldrich
- Departments of Biochemistry and Cell Biology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Shawn M. Lyons
- Departments of Biochemistry and Cell Biology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Rachel Litman Flynn
- Departments of Pharmacology and Experimental Therapeutics, and Medicine, Cancer Center, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| |
Collapse
|
5
|
Kanagaraj R, Mitter R, Kantidakis T, Edwards MM, Benitez A, Chakravarty P, Fu B, Becherel O, Yang F, Lavin MF, Koren A, Stewart A, West SC. Integrated genome and transcriptome analyses reveal the mechanism of genome instability in ataxia with oculomotor apraxia 2. Proc Natl Acad Sci U S A 2022; 119:e2114314119. [PMID: 35042798 PMCID: PMC8795503 DOI: 10.1073/pnas.2114314119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 12/14/2021] [Indexed: 12/21/2022] Open
Abstract
Mutations in the SETX gene, which encodes Senataxin, are associated with the progressive neurodegenerative diseases ataxia with oculomotor apraxia 2 (AOA2) and amyotrophic lateral sclerosis 4 (ALS4). To identify the causal defect in AOA2, patient-derived cells and SETX knockouts (human and mouse) were analyzed using integrated genomic and transcriptomic approaches. A genome-wide increase in chromosome instability (gains and losses) within genes and at chromosome fragile sites was observed, resulting in changes to gene-expression profiles. Transcription stress near promoters correlated with high GCskew and the accumulation of R-loops at promoter-proximal regions, which localized with chromosomal regions where gains and losses were observed. In the absence of Senataxin, the Cockayne syndrome protein CSB was required for the recruitment of the transcription-coupled repair endonucleases (XPG and XPF) and RAD52 recombination protein to target and resolve transcription bubbles containing R-loops, leading to genomic instability. These results show that transcription stress is an important contributor to SETX mutation-associated chromosome fragility and AOA2.
Collapse
Affiliation(s)
- Radhakrishnan Kanagaraj
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom;
| | - Richard Mitter
- Bioinformatics and Biostatistics, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | | | - Matthew M Edwards
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Anaid Benitez
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Probir Chakravarty
- Bioinformatics and Biostatistics, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Beiyuan Fu
- Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SA, United Kingdom
| | - Olivier Becherel
- Center for Clinical Research, University of Queensland, Herston, QLD 4029, Australia
| | - Fengtang Yang
- Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SA, United Kingdom
| | - Martin F Lavin
- Center for Clinical Research, University of Queensland, Herston, QLD 4029, Australia
| | - Amnon Koren
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Aengus Stewart
- Bioinformatics and Biostatistics, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Stephen C West
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom;
| |
Collapse
|
6
|
Pławińska-Czarnak J, Majewska A, Zarzyńska J, Bogdan J, Kaba J, Anusz K, Bagnicka E. Gene Expression Profile in Peripheral Blood Nuclear Cells of Small Ruminant Lentivirus-Seropositive and Seronegative Dairy Goats in Their First Lactation. Animals (Basel) 2021; 11:ani11040940. [PMID: 33810360 PMCID: PMC8066113 DOI: 10.3390/ani11040940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 12/19/2022] Open
Abstract
Simple Summary Caprine arthritis encephalitis, caused by small ruminant lentivirus (SRLV), is a disease that develops with various signs in adult goats, e.g., arthritis, mastitis, and progressive weight loss, while in goat kids, the disease presents with only neuropathy and extremely rarely. The disease results in reduced milk production and economic losses in herds of goats. Previously described changes in single gene expression do not fully explain all the processes occurring in the infected goats. Therefore, the present study describes the first use of a transcriptomic array designed specifically for goats in Poland. Its aim was to investigate the gene expression profiles of peripheral blood nuclear cells from SRLV-seropositive and SRLV-seronegative goats using a custom-made Capra hircus gene expression array. Just four genes out of ~50,000 were found to have differential expression; moreover, changes in their expression suggest an active inflammatory mechanism in SRLV-seropositive goats at the early stage of SRLV infection. Abstract The immune response to a viral antigen causes inflammatory cell infiltration to the tissue, which creates a suitable environment for the replication of the virus in macrophages, and the recruitment of more monocytes to the site of infection, or latently infected monocytes. The aim of the study was to analyze the transcriptomic profile of peripheral blood nuclear cells isolated from SRLV-seropositive and SRLV-negative goats at the peak of their first lactation. SRLV-seropositive goats were probably infected via colostrum. Custom transcriptomic microarrays for goats were designed and developed, namely the Capra hircus gene expression array, which features ~50,000 unique transcripts per microarray. Only four genes were differentially expressed, with up-regulated expression of the GIMAP2, SSC5D and SETX genes, and down-regulated expression of the GPR37 gene in SRLV-seropositive vs. SRLV-seronegative goats. However, in an RT-qPCR analysis, the result for the SETX gene was not confirmed. The differences in the expressions of the studied genes indicate an active inflammatory process in the SRLV-seropositive goats at the early stage of infection.
Collapse
Affiliation(s)
- Joanna Pławińska-Czarnak
- Department of Food Hygiene and Public Health Protection, Institute of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland; (J.Z.); (J.B.); (K.A.)
- Correspondence:
| | - Alicja Majewska
- Department of Physiology Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland;
| | - Joanna Zarzyńska
- Department of Food Hygiene and Public Health Protection, Institute of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland; (J.Z.); (J.B.); (K.A.)
| | - Janusz Bogdan
- Department of Food Hygiene and Public Health Protection, Institute of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland; (J.Z.); (J.B.); (K.A.)
| | - Jarosław Kaba
- Division of Epidemiology and Veterinary Management, Institute of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 159c, 02-776 Warsaw, Poland;
| | - Krzysztof Anusz
- Department of Food Hygiene and Public Health Protection, Institute of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland; (J.Z.); (J.B.); (K.A.)
| | - Emilia Bagnicka
- Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postepu 36A, Jastrzebiec, 05-552 Magdalenka, Poland;
| |
Collapse
|
7
|
Volkening K, Farhan SMK, Kao J, Leystra-Lantz C, Ang LC, McIntyre A, Wang J, Hegele RA, Strong MJ. Evidence of synergism among three genetic variants in a patient with LMNA-related lipodystrophy and amyotrophic lateral sclerosis leading to a remarkable nuclear phenotype. Mol Cell Biochem 2021; 476:2633-2650. [PMID: 33661429 PMCID: PMC8192393 DOI: 10.1007/s11010-021-04103-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 02/06/2021] [Indexed: 11/25/2022]
Abstract
Neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), can be clinically heterogeneous which may be explained by the co-inheritance of multiple genetic variants that modify the clinical course. In this study we examine variants in three genes in a family with one individual presenting with ALS and lipodystrophy. Sequencing revealed a p.Gly602Ser variant in LMNA, and two additional variants, one each in SETX (g.intron10-13delCTT) and FUS (p.Gly167_Gly168del). These latter genes have been linked to ALS. All family members were genotyped and each variant, and each combination of variants detected, were functionally evaluated in vitro regarding effects on cell survival, expression patterns and cellular phenotype. Muscle biopsy retrieved from the individual with ALS showed leakage of chromatin from the nucleus, a phenotype that was recapitulated in vitro with expression of all three variants simultaneously. Individually expressed variants gave cellular phenotypes there were unremarkable. Interestingly the FUS variant appears to be protective against the effects of the SETX and the LMNA variants on cell viability and may indicate loss of interaction of FUS with SETX and/or R-loops. We conclude that these findings support genetic modifications as an explanation of the clinical heterogeneity observed in human disease.
Collapse
Affiliation(s)
- Kathryn Volkening
- Molecular Medicine, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Sali M K Farhan
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Jessica Kao
- Molecular Medicine, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Cheryl Leystra-Lantz
- Molecular Medicine, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Lee Cyn Ang
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- Department of Pathology and Laboratory Medicine, London Health Sciences Centre-University Hospital, London, ON, Canada
| | - Adam McIntyre
- Blackburn Cardiovascular Genetics Lab, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Jian Wang
- Blackburn Cardiovascular Genetics Lab, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Robert A Hegele
- Department of Pathology and Laboratory Medicine, London Health Sciences Centre-University Hospital, London, ON, Canada
- Blackburn Cardiovascular Genetics Lab, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- Department of Biochemistry, Western University, London, ON, Canada
| | - Michael J Strong
- Molecular Medicine, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
| |
Collapse
|
8
|
Abstract
Physiological and pathological roles for R-loop structures continue to be discovered, and studies suggest that R-loops could contribute to human disease. R-loops are nucleic acid structures characterized by a DNA:RNA hybrid and displaced single-stranded DNA that occur in connection with transcription. R-loops form naturally and have been shown to be important for a number of physiological processes such as mitochondrial replication initiation, class switch recombination, DNA repair, modulating DNA topology, and regulation of gene expression. However, subsets of R-loops or persistent R-loops lead to DNA breaks, chromosome rearrangement, and genome instability. In addition, R-loops have been linked to human diseases, specifically neurological disorders and cancer. Of the large amount of research produced recently on R-loops, this review covers evidence for R-loop involvement in normal cellular physiology and pathophysiology, as well as describing factors that contribute to R-loop regulation.
Collapse
Affiliation(s)
- Ryan Patrick Mackay
- Department of Molecular and Cellular Physiology and Louisiana State University Health Sciences Center - Shreveport, Shreveport, Louisiana, USA
| | - Qinqin Xu
- Department of Otolaryngology - Head & Neck Surgery, Louisiana State University Health Sciences Center - Shreveport, Shreveport, Louisiana, USA
| | - Paul M Weinberger
- Department of Molecular and Cellular Physiology and Louisiana State University Health Sciences Center - Shreveport, Shreveport, Louisiana, USA.,Department of Otolaryngology - Head & Neck Surgery, Louisiana State University Health Sciences Center - Shreveport, Shreveport, Louisiana, USA
| |
Collapse
|
9
|
Disruption of Spermatogenesis and Infertility in Ataxia with Oculomotor Apraxia Type 2 (AOA2). THE CEREBELLUM 2019; 18:448-456. [PMID: 30778901 DOI: 10.1007/s12311-019-01012-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ataxia with oculomotor apraxia type 2 (AOA2) is a rare autosomal recessive cerebellar ataxia characterized by onset between 10 and 20 years of age and a range of neurological features that include progressive cerebellar atrophy, axonal sensorimotor neuropathy, oculomotor apraxia in a majority of patients, and elevated serum alpha-fetoprotein (AFP). AOA2 is caused by mutation of the SETX gene which encodes senataxin, a DNA/RNA helicase involved in transcription regulation, RNA processing, and DNA maintenance. Disruption of senataxin in rodents led to defective spermatogenesis and sterility in males uncovering a key role for senataxin in male germ cell survival. Here, we report the first clinical and cellular evidence of impaired spermatogenesis in AOA2 patients. We assessed sperm production in three AOA2 patients and testicular pathology in one patient and compared the findings to those of Setx-knockout mice. Sperm production was impaired in all patients assessed (3/3, 100%). Analyses of testicular biopsies from an AOA2 patient recapitulate features of the histology seen in Setx-knockout mice, strongly suggesting an underlying mechanism centering on DNA-damage-mediated germ cell apoptosis. These findings support a role for senataxin in human reproductive function and highlight a novel clinical feature of AOA2 that extends the extra-neurological roles of senataxin. This raises an important reproductive counseling issue for clinicians, and fertility specialists should be aware of SETX mutations as a possible diagnosis in young male patients presenting with oligospermia or azoospermia since infertility may presage the later onset of neurological manifestations in some individuals.
Collapse
|
10
|
Kannan A, Bhatia K, Branzei D, Gangwani L. Combined deficiency of Senataxin and DNA-PKcs causes DNA damage accumulation and neurodegeneration in spinal muscular atrophy. Nucleic Acids Res 2019; 46:8326-8346. [PMID: 30010942 PMCID: PMC6144794 DOI: 10.1093/nar/gky641] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/05/2018] [Indexed: 12/12/2022] Open
Abstract
Chronic low levels of survival motor neuron (SMN) protein cause spinal muscular atrophy (SMA). SMN is ubiquitously expressed, but the mechanisms underlying predominant neuron degeneration in SMA are poorly understood. We report that chronic low levels of SMN cause Senataxin (SETX)-deficiency, which results in increased RNA–DNA hybrids (R-loops) and DNA double-strand breaks (DSBs), and deficiency of DNA-activated protein kinase-catalytic subunit (DNA-PKcs), which impairs DSB repair. Consequently, DNA damage accumulates in patient cells, SMA mice neurons and patient spinal cord tissues. In dividing cells, DSBs are repaired by homologous recombination (HR) and non-homologous end joining (NHEJ) pathways, but neurons predominantly use NHEJ, which relies on DNA-PKcs activity. In SMA dividing cells, HR repairs DSBs and supports cellular proliferation. In SMA neurons, DNA-PKcs-deficiency causes defects in NHEJ-mediated repair leading to DNA damage accumulation and neurodegeneration. Restoration of SMN levels rescues SETX and DNA-PKcs deficiencies and DSB accumulation in SMA neurons and patient cells. Moreover, SETX overexpression in SMA neurons reduces R-loops and DNA damage, and rescues neurodegeneration. Our findings identify combined deficiency of SETX and DNA-PKcs stemming downstream of SMN as an underlying cause of DSBs accumulation, genomic instability and neurodegeneration in SMA and suggest SETX as a potential therapeutic target for SMA.
Collapse
Affiliation(s)
- Annapoorna Kannan
- Center of Emphasis in Neurosciences, Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905.,Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905
| | - Kanchan Bhatia
- Center of Emphasis in Neurosciences, Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905.,Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905
| | - Dana Branzei
- The FIRC Institute of Molecular Oncology Foundation, IFOM Foundation, Via Adamello 16, Milan 20139, Italy.,Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, Pavia 27100, Italy
| | - Laxman Gangwani
- Center of Emphasis in Neurosciences, Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905.,Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905.,Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905, USA
| |
Collapse
|
11
|
Abstract
The maintenance of genome stability in eukaryotic cells relies on accurate and efficient replication along each chromosome following every cell division. The terminal position, repetitive sequence, and structural complexities of the telomeric DNA make the telomere an inherently difficult region to replicate within the genome. Thus, despite functioning to protect genome stability mammalian telomeres are also a source of replication stress and have been recognized as common fragile sites within the genome. Telomere fragility is exacerbated at telomeres that rely on the Alternative Lengthening of Telomeres (ALT) pathway. Like common fragile sites, ALT telomeres are prone to chromosome breaks and are frequent sites of recombination suggesting that ALT telomeres are subjected to chronic replication stress. Here, we will review the features of telomeric DNA that challenge the replication machinery and also how the cell overcomes these challenges to maintain telomere stability and ensure the faithful duplication of the human genome.
Collapse
Affiliation(s)
- Emily Mason-Osann
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA
| | - Himabindu Gali
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA
| | - Rachel Litman Flynn
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA.
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA.
| |
Collapse
|
12
|
Abstract
R loops are transient three-stranded nucleic acid structures that form physiologically during transcription when a nascent RNA transcript hybridizes with the DNA template strand, leaving a single strand of displaced nontemplate DNA. However, aberrant persistence of R-loops can cause DNA damage by inducing genomic instability. Indeed, evidence has emerged that R-loops might represent a key element in the pathogenesis of human diseases, including cancer, neurodegeneration, and motor neuron disorders. Mutations in genes directly involved in R-loop biology, such as SETX (senataxin), or unstable DNA expansion eliciting R-loop generation, such as C9ORF72 HRE, can cause DNA damage and ultimately result in motor neuron cell death. In this review, we discuss current advancements in this field with a specific focus on motor neuron diseases associated with deregulation of R-loop structures. These mechanisms can represent novel therapeutic targets for these devastating, incurable diseases.
Collapse
|
13
|
A senataxin-associated exonuclease SAN1 is required for resistance to DNA interstrand cross-links. Nat Commun 2018; 9:2592. [PMID: 29968717 PMCID: PMC6030175 DOI: 10.1038/s41467-018-05008-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 06/07/2018] [Indexed: 02/02/2023] Open
Abstract
Interstrand DNA cross-links (ICLs) block both replication and transcription, and are commonly repaired by the Fanconi anemia (FA) pathway. However, FA-independent repair mechanisms of ICLs remain poorly understood. Here we report a previously uncharacterized protein, SAN1, as a 5′ exonuclease that acts independently of the FA pathway in response to ICLs. Deletion of SAN1 in HeLa cells and mouse embryonic fibroblasts causes sensitivity to ICLs, which is prevented by re-expression of wild type but not nuclease-dead SAN1. SAN1 deletion causes DNA damage and radial chromosome formation following treatment with Mitomycin C, phenocopying defects in the FA pathway. However, SAN1 deletion is not epistatic with FANCD2, a core FA pathway component. Unexpectedly, SAN1 binds to Senataxin (SETX), an RNA/DNA helicase that resolves R-loops. SAN1-SETX binding is increased by ICLs, and is required to prevent cross-link sensitivity. We propose that SAN1 functions with SETX in a pathway necessary for resistance to ICLs. When DNA interstrand cross-links damage occurs, it causes disruption of replication and transcription. Here the authors identify FAM120B/SAN1, a 5′ exonuclease involved in the repair process of Interstrand Crosslinks independently of the Fanconi Anemia pathway.
Collapse
|
14
|
Senataxin resolves RNA:DNA hybrids forming at DNA double-strand breaks to prevent translocations. Nat Commun 2018; 9:533. [PMID: 29416069 PMCID: PMC5803260 DOI: 10.1038/s41467-018-02894-w] [Citation(s) in RCA: 199] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 01/05/2018] [Indexed: 12/21/2022] Open
Abstract
Ataxia with oculomotor apraxia 2 (AOA-2) and amyotrophic lateral sclerosis (ALS4) are neurological disorders caused by mutations in the gene encoding for senataxin (SETX), a putative RNA:DNA helicase involved in transcription and in the maintenance of genome integrity. Here, using ChIP followed by high throughput sequencing (ChIP-seq), we report that senataxin is recruited at DNA double-strand breaks (DSBs) when they occur in transcriptionally active loci. Genome-wide mapping unveiled that RNA:DNA hybrids accumulate on DSB-flanking chromatin but display a narrow, DSB-induced, depletion near DNA ends coinciding with senataxin binding. Although neither required for resection nor for timely repair of DSBs, senataxin was found to promote Rad51 recruitment, to minimize illegitimate rejoining of distant DNA ends and to sustain cell viability following DSB production in active genes. Our data suggest that senataxin functions at DSBs in order to limit translocations and ensure cell viability, providing new insights on AOA2/ALS4 neuropathies.
Collapse
|
15
|
Foley NM, Hughes GM, Huang Z, Clarke M, Jebb D, Whelan CV, Petit EJ, Touzalin F, Farcy O, Jones G, Ransome RD, Kacprzyk J, O’Connell MJ, Kerth G, Rebelo H, Rodrigues L, Puechmaille SJ, Teeling EC. Growing old, yet staying young: The role of telomeres in bats' exceptional longevity. SCIENCE ADVANCES 2018; 4:eaao0926. [PMID: 29441358 PMCID: PMC5810611 DOI: 10.1126/sciadv.aao0926] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 01/10/2018] [Indexed: 05/02/2023]
Abstract
Understanding aging is a grand challenge in biology. Exceptionally long-lived animals have mechanisms that underpin extreme longevity. Telomeres are protective nucleotide repeats on chromosome tips that shorten with cell division, potentially limiting life span. Bats are the longest-lived mammals for their size, but it is unknown whether their telomeres shorten. Using >60 years of cumulative mark-recapture field data, we show that telomeres shorten with age in Rhinolophus ferrumequinum and Miniopterus schreibersii, but not in the bat genus with greatest longevity, Myotis. As in humans, telomerase is not expressed in Myotis myotis blood or fibroblasts. Selection tests on telomere maintenance genes show that ATM and SETX, which repair and prevent DNA damage, potentially mediate telomere dynamics in Myotis bats. Twenty-one telomere maintenance genes are differentially expressed in Myotis, of which 14 are enriched for DNA repair, and 5 for alternative telomere-lengthening mechanisms. We demonstrate how telomeres, telomerase, and DNA repair genes have contributed to the evolution of exceptional longevity in Myotis bats, advancing our understanding of healthy aging.
Collapse
Affiliation(s)
- Nicole M. Foley
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Graham M. Hughes
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Zixia Huang
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Michael Clarke
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - David Jebb
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Conor V. Whelan
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Eric J. Petit
- Ecologie et Santé des Ecosystèmes (ESE), Ecology and Ecosystem Health, Agrocampus Ouest, INRA, 35042 Rennes, France
| | - Frédéric Touzalin
- Laboratoire Évolution et Diversité Biologique, UMR 5174: Université Toulouse III, CNRS, ENFA, 118 Route de Narbonne, 31062 Toulouse cedex 9, France
| | - Olivier Farcy
- Le Groupe Chiroptères de Bretagne Vivante/SEPNB, 19 rue Gouesnou BP 62132, 29221 Brest cedex 2, France
| | - Gareth Jones
- School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TH, UK
| | - Roger D. Ransome
- School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TH, UK
| | - Joanna Kacprzyk
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Mary J. O’Connell
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Gerald Kerth
- University of Greifswald, Loitzer Strasse 26, 17489 Greifswald, Germany
| | - Hugo Rebelo
- School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TH, UK
- CIBIO-InBIO, Universidade do Porto, Campus de Agrário Vairão, Rua Padre Armando Quintas, 4485-661 Vairão, Portugal
- CEABN-InBIO, Instituto Superior de Agronomia, Universidade de Lisboa, 1349-015 Lisboa, Portugal
| | - Luísa Rodrigues
- Instituto da Conservação da Natureza e das Florestas, Avenida da República 16-16B, 1050-191 Lisboa, Portugal
| | - Sébastien J. Puechmaille
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
- University of Greifswald, Loitzer Strasse 26, 17489 Greifswald, Germany
| | - Emma C. Teeling
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
- Corresponding author.
| |
Collapse
|
16
|
Bennett CL, La Spada AR. Senataxin, A Novel Helicase at the Interface of RNA Transcriptome Regulation and Neurobiology: From Normal Function to Pathological Roles in Motor Neuron Disease and Cerebellar Degeneration. ADVANCES IN NEUROBIOLOGY 2018; 20:265-281. [DOI: 10.1007/978-3-319-89689-2_10] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
|
17
|
Groh M, Albulescu LO, Cristini A, Gromak N. Senataxin: Genome Guardian at the Interface of Transcription and Neurodegeneration. J Mol Biol 2016; 429:3181-3195. [PMID: 27771483 DOI: 10.1016/j.jmb.2016.10.021] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/14/2016] [Accepted: 10/15/2016] [Indexed: 12/12/2022]
Abstract
R-loops comprise an RNA/DNA hybrid and a displaced single-stranded DNA. They play crucial biological functions and are implicated in neurological diseases, including ataxias, amyotrophic lateral sclerosis, nucleotide expansion disorders (Friedreich ataxia and fragile X syndrome), and cancer. Currently, it is unclear which mechanisms cause R-loop structures to become pathogenic. The RNA/DNA helicase senataxin (SETX) is one of the best characterised R-loop-binding factors in vivo. Mutations in SETX are linked to two neurodegenerative disorders: ataxia with oculomotor apraxia type 2 (AOA2) and amyotrophic lateral sclerosis type 4 (ALS4). SETX is known to play a role in transcription, neurogenesis, and antiviral response. Here, we review the causes of R-loop dysregulation in neurodegenerative diseases and how these structures contribute to pathomechanisms. We will discuss the importance of SETX as a genome guardian in suppressing aberrant R-loop formation and analyse how SETX mutations can lead to neurodegeneration in AOA2/ALS4. Finally, we will discuss the implications for other R-loop-associated neurodegenerative diseases and point to future therapeutic approaches to treat these disorders.
Collapse
Affiliation(s)
- Matthias Groh
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK
| | - Laura Oana Albulescu
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK
| | - Agnese Cristini
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK
| | - Natalia Gromak
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK.
| |
Collapse
|
18
|
Richard P, Manley JL. R Loops and Links to Human Disease. J Mol Biol 2016; 429:3168-3180. [PMID: 27600412 DOI: 10.1016/j.jmb.2016.08.031] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/26/2016] [Accepted: 08/31/2016] [Indexed: 12/13/2022]
Abstract
Aberrant R-loop structures are increasingly being realized as an important contributor to human disease. R loops, which are mainly co-transcriptional, abundant RNA/DNA hybrids, form naturally and can indeed be beneficial for transcription regulation at certain loci. However, their unwanted persistence elsewhere or in particular situations can lead to DNA double-strand breaks, chromosome rearrangements, and hypermutation, which are all sources of genomic instability. Mutations in genes involved in R-loop resolution or mutations leading to R-loop formation at specific genes affect the normal physiology of the cell. We discuss here the examples of diseases for which a link with R loops has been described, as well as how disease-causing mutations might participate in the development and/or progression of diseases that include repeat-associated conditions, other neurological disorders, and cancers.
Collapse
Affiliation(s)
- Patricia Richard
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| |
Collapse
|
19
|
Senataxin controls meiotic silencing through ATR activation and chromatin remodeling. Cell Discov 2015; 1:15025. [PMID: 27462424 PMCID: PMC4860845 DOI: 10.1038/celldisc.2015.25] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 07/17/2015] [Indexed: 12/13/2022] Open
Abstract
Senataxin, defective in ataxia oculomotor apraxia type 2, protects the genome by facilitating the resolution of RNA–DNA hybrids (R-loops) and other aspects of RNA processing. Disruption of this gene in mice causes failure of meiotic recombination and defective meiotic sex chromosome inactivation, leading to male infertility. Here we provide evidence that the disruption of Setx leads to reduced SUMOylation and disruption of protein localization across the XY body during meiosis. We demonstrate that senataxin and other DNA damage repair proteins, including ataxia telangiectasia and Rad3-related protein-interacting partner, are SUMOylated, and a marked downregulation of both ataxia telangiectasia and Rad3-related protein-interacting partner and TopBP1 leading to defective activation and signaling through ataxia telangiectasia and Rad3-related protein occurs in the absence of senataxin. Furthermore, chromodomain helicase DNA-binding protein 4, a component of the nucleosome remodeling and deacetylase chromatin remodeler that interacts with both ataxia telangiectasia and Rad3-related protein and senataxin was not recruited efficiently to the XY body, triggering altered histone acetylation and chromatin conformation in Setx−/− pachytene-staged spermatocytes. These results demonstrate that senataxin has a critical role in ataxia telangiectasia and Rad3-related protein- and chromodomain helicase DNA-binding protein 4-mediated transcriptional silencing and chromatin remodeling during meiosis providing greater insight into its critical role in gene regulation to protect against neurodegeneration.
Collapse
|
20
|
Becherel OJ, Sun J, Yeo AJ, Nayler S, Fogel BL, Gao F, Coppola G, Criscuolo C, De Michele G, Wolvetang E, Lavin MF. A new model to study neurodegeneration in ataxia oculomotor apraxia type 2. Hum Mol Genet 2015; 24:5759-74. [PMID: 26231220 DOI: 10.1093/hmg/ddv296] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 07/20/2015] [Indexed: 12/18/2022] Open
Abstract
Ataxia oculomotor apraxia type 2 (AOA2) is a rare autosomal recessive cerebellar ataxia. Recent evidence suggests that the protein defective in this syndrome, senataxin (SETX), functions in RNA processing to protect the integrity of the genome. To date, only patient-derived lymphoblastoid cells, fibroblasts and SETX knockdown cells were available to investigate AOA2. Recent disruption of the Setx gene in mice did not lead to neurobehavioral defects or neurodegeneration, making it difficult to study the etiology of AOA2. To develop a more relevant neuronal model to study neurodegeneration in AOA2, we derived neural progenitors from a patient with AOA2 and a control by induced pluripotent stem cell (iPSC) reprogramming of fibroblasts. AOA2 iPSC and neural progenitors exhibit increased levels of oxidative damage, DNA double-strand breaks, increased DNA damage-induced cell death and R-loop accumulation. Genome-wide expression and weighted gene co-expression network analysis in these neural progenitors identified both previously reported and novel affected genes and cellular pathways associated with senataxin dysfunction and the pathophysiology of AOA2, providing further insight into the role of senataxin in regulating gene expression on a genome-wide scale. These data show that iPSCs can be generated from patients with the autosomal recessive ataxia, AOA2, differentiated into neurons, and that both cell types recapitulate the AOA2 cellular phenotype. This represents a novel and appropriate model system to investigate neurodegeneration in this syndrome.
Collapse
Affiliation(s)
- Olivier J Becherel
- UQ Centre for Clinical Research (UQCCR), School of Chemistry and Molecular Biosciences and
| | - Jane Sun
- Australian Institute for Bioengineering and Nanotechnology
| | - Abrey J Yeo
- UQ Centre for Clinical Research (UQCCR), School of Medicine, The University of Queensland, Brisbane, QLD 4029, Australia
| | - Sam Nayler
- Australian Institute for Bioengineering and Nanotechnology
| | | | - Fuying Gao
- Department of Psychiatry, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA and
| | - Giovanni Coppola
- Department of Neurology and Department of Psychiatry, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA and
| | - Chiara Criscuolo
- Department of Neuroscience and Reproductive and Odontostomatological Sciences, Federico II University, Napoli, Italy
| | - Giuseppe De Michele
- Department of Neuroscience and Reproductive and Odontostomatological Sciences, Federico II University, Napoli, Italy
| | | | | |
Collapse
|
21
|
Abstract
The RNA polymerase II transcription cycle is often divided into three major stages: initiation, elongation, and termination. Research over the last decade has blurred these divisions and emphasized the tightly regulated transitions that occur as RNA polymerase II synthesizes a transcript from start to finish. Transcription termination, the process that marks the end of transcription elongation, is regulated by proteins that interact with the polymerase, nascent transcript, and/or chromatin template. The failure to terminate transcription can cause accumulation of aberrant transcripts and interfere with transcription at downstream genes. Here, we review the mechanism, regulation, and physiological impact of a termination pathway that targets small noncoding transcripts produced by RNA polymerase II. We emphasize the Nrd1-Nab3-Sen1 pathway in yeast, in which the process has been extensively studied. The importance of understanding small RNA termination pathways is underscored by the need to control noncoding transcription in eukaryotic genomes.
Collapse
Affiliation(s)
- Karen M Arndt
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260;
| | | |
Collapse
|
22
|
Carroll J, Page TKW, Chiang SC, Kalmar B, Bode D, Greensmith L, Mckinnon PJ, Thorpe JR, Hafezparast M, El-Khamisy SF. Expression of a pathogenic mutation of SOD1 sensitizes aprataxin-deficient cells and mice to oxidative stress and triggers hallmarks of premature ageing. Hum Mol Genet 2015; 24:828-40. [PMID: 25274775 PMCID: PMC4291253 DOI: 10.1093/hmg/ddu500] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/02/2014] [Accepted: 09/26/2014] [Indexed: 11/13/2022] Open
Abstract
Aprataxin (APTX) deficiency causes progressive cerebellar degeneration, ataxia and oculomotor apraxia in man. Cell free assays and crystal structure studies demonstrate a role for APTX in resolving 5'-adenylated nucleic acid breaks, however, APTX function in vertebrates remains unclear due to the lack of an appropriate model system. Here, we generated a murine model in which a pathogenic mutant of superoxide dismutase 1 (SOD1(G93A)) is expressed in an Aptx-/- mouse strain. We report a delayed population doubling and accelerated senescence in Aptx-/- primary mouse fibroblasts, which is not due to detectable telomere instability or cell cycle deregulation but is associated with a reduction in transcription recovery following oxidative stress. Expression of SOD1(G93A) uncovers a survival defect ex vivo in cultured cells and in vivo in tissues lacking Aptx. The surviving neurons feature numerous and deep nuclear envelope invaginations, a hallmark of cellular stress. Furthermore, they possess an elevated number of high-density nuclear regions and a concomitant increase in histone H3 K9 trimethylation, hallmarks of silenced chromatin. Finally, the accelerated cellular senescence was also observed at the organismal level as shown by down-regulation of insulin-like growth factor 1 (IGF-1), a hallmark of premature ageing. Together, this study demonstrates a protective role of Aptx in vivo and suggests that its loss results in progressive accumulation of DNA breaks in the nervous system, triggering hallmarks of premature ageing, systemically.
Collapse
Affiliation(s)
- Jean Carroll
- Genome Damage and Stability Center, University of Sussex, Brighton BN1 9RQ, UK
| | - Tristan K W Page
- School of Life Science, University of Sussex, Brighton BN1 9QG, UK
| | - Shih-Chieh Chiang
- Department of Molecular Biology and Biotechnology, Krebs Institute, University of Sheffield, Sheffield S10 2TN, UK
| | - Bernadett Kalmar
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - David Bode
- School of Life Science, University of Sussex, Brighton BN1 9QG, UK
| | - Linda Greensmith
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Peter J Mckinnon
- Department of Genetics, St Jude Children's Research Hospital, Memphis, TN 38105-3678, USA and
| | - Julian R Thorpe
- School of Life Science, University of Sussex, Brighton BN1 9QG, UK
| | | | - Sherif F El-Khamisy
- Genome Damage and Stability Center, University of Sussex, Brighton BN1 9RQ, UK Department of Molecular Biology and Biotechnology, Krebs Institute, University of Sheffield, Sheffield S10 2TN, UK Center of Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
| |
Collapse
|
23
|
Abstract
R-loops are cellular structures composed of an RNA/DNA hybrid, which is formed when the RNA hybridises to a complementary DNA strand and a displaced single-stranded DNA. R-loops have been detected in various organisms from bacteria to mammals and play crucial roles in regulating gene expression, DNA and histone modifications, immunoglobulin class switch recombination, DNA replication, and genome stability. Recent evidence suggests that R-loops are also involved in molecular mechanisms of neurological diseases and cancer. In addition, mutations in factors implicated in R-loop biology, such as RNase H and SETX (senataxin), lead to devastating human neurodegenerative disorders, highlighting the importance of correctly regulating the level of R-loops in human cells. In this review we summarise current advances in this field, with a particular focus on diseases associated with dysregulation of R-loop structures. We also discuss potential therapeutic approaches for such diseases and highlight future research directions.
Collapse
Affiliation(s)
- Matthias Groh
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Natalia Gromak
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- * E-mail:
| |
Collapse
|
24
|
Vantaggiato C, Cantoni O, Guidarelli A, Romaniello R, Citterio A, Arrigoni F, Doneda C, Castelli M, Airoldi G, Bresolin N, Borgatti R, Bassi MT. Novel SETX variants in a patient with ataxia, neuropathy, and oculomotor apraxia are associated with normal sensitivity to oxidative DNA damaging agents. Brain Dev 2014; 36:682-9. [PMID: 24183476 DOI: 10.1016/j.braindev.2013.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND Homozygous and compound heterozygous mutations in SETX are associated with AOA2 disease, a recessive form of ataxia with oculomotor apraxia and neuropathy with onset of ataxia between the first and second decade of life. The majority of the AOA2 mutated cell lines tested show hypersensitivity to oxidative DNA damaging agents, with one exception. RESULTS We describe a patient presenting with early-onset progressive ataxia, oculomotor apraxia, axonal sensory-motor neuropathy, optic atrophy, delayed psychomotor development, and a behavior disorder. The patient carries two novel missense variants in the SETX gene. Based on the hypothesis that the patient's clinical phenotype may represent an atypical form of the AOA2 disease, we tested the patient-derived cell line for hypersensitivity to oxidative DNA damaging agents, with negative results. CONCLUSIONS The lack of hypersensitivity we observed may be explained either by considering the atypical clinical picture of the patient analyzed or, alternatively, by hypothesizing that the variants detected are not the cause of the observed phenotype. Consistent with the first hypothesis of an atypical AOA2 form and based on the multiple functions of senataxin reported so far, it is likely that different sets of SETX mutations/variants may have variable functional effects that still need to be functionally characterized. The possibility that the severe and complicated clinical picture presented by the patient described here represents a clinical entity differing from the known recessive ataxias should be considered as well.
Collapse
Affiliation(s)
- Chiara Vantaggiato
- Scientific Institute IRCCS E. Medea, Laboratory of Molecular Biology, 23842 Bosisio Parini, Lecco, Italy
| | - Orazio Cantoni
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Urbino, Italy
| | - Andrea Guidarelli
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Urbino, Italy
| | - Romina Romaniello
- Scientific Institute IRCCS E. Medea, Neuropsychiatry and Neurorehabilitation Unit, Bosisio Parini, Lecco, Italy
| | - Andrea Citterio
- Scientific Institute IRCCS E. Medea, Laboratory of Molecular Biology, 23842 Bosisio Parini, Lecco, Italy
| | - Filippo Arrigoni
- Scientific Institute IRCCS E.Medea, Neuroimaging Unit, Bosisio Parini, Lecco, Italy
| | - Chiara Doneda
- Radiology and Pediatric Neuroradiology, Buzzi Hospital, Milan, Italy
| | - Marianna Castelli
- Scientific Institute IRCCS E. Medea, Laboratory of Molecular Biology, 23842 Bosisio Parini, Lecco, Italy
| | - Giovanni Airoldi
- Scientific Institute IRCCS E. Medea, Laboratory of Molecular Biology, 23842 Bosisio Parini, Lecco, Italy
| | - Nereo Bresolin
- Scientific Institute IRCCS E. Medea, Laboratory of Molecular Biology, 23842 Bosisio Parini, Lecco, Italy; Dino Ferrari Centre, IRCCS Ca' Granda, Ospedale Maggiore Policlinico Foundation, Department of Physiopathology and Transplantation, University of Milan, Italy
| | - Renato Borgatti
- Scientific Institute IRCCS E. Medea, Neuropsychiatry and Neurorehabilitation Unit, Bosisio Parini, Lecco, Italy
| | - Maria Teresa Bassi
- Scientific Institute IRCCS E. Medea, Laboratory of Molecular Biology, 23842 Bosisio Parini, Lecco, Italy.
| |
Collapse
|
25
|
|
26
|
DNA repair abnormalities leading to ataxia: shared neurological phenotypes and risk factors. Neurogenetics 2014; 15:217-28. [PMID: 25038946 DOI: 10.1007/s10048-014-0415-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/11/2014] [Indexed: 02/06/2023]
Abstract
Since identification of mutations in the ATM gene leading to ataxia-telangiectasia, enormous efforts have been devoted to discovering the roles this protein plays in DNA repair as well as other cellular functions. Even before the identification of ATM mutations, it was clear that other diseases with different genomic loci had very similar neurological symptoms. There has been significant progress in understanding why cancer and immunodeficiency occur in ataxia-telangiectasia even though many details remain to be determined, but the field is no closer to determining why the nervous system requires ATM and other DNA repair genes. Even though rodent disease models have similar DNA repair abnormalities as the human diseases, they have no consistent, robust neuropathological phenotype making it difficult to understand the neurological underpinnings of disease. Therefore, it may be useful to reassess the neurological and neuropathological characteristics of ataxia-telangiectasia in human patients to look for potential commonalities in DNA repair diseases that result in ataxia. In doing so, it is clear that ataxia-telangiectasia and similar diseases share neurological features other than merely ataxia, such as length-dependent motor and sensory neuropathies, and that the neuroanatomical localization for these symptoms is understood. Cells affected in ataxia-telangiectasia and similar diseases are some of the largest single nucleated cells in the body. In addition, a subset of these diseases also has extrapyramidal movements and oculomotor apraxia. These neurological and neuropathological similarities may indicate a common DNA repair related pathogenesis with very large cell size as a critical risk factor.
Collapse
|
27
|
Bennett CL, Chen Y, Vignali M, Lo RS, Mason AG, Unal A, Huq Saifee NP, Fields S, La Spada AR. Protein interaction analysis of senataxin and the ALS4 L389S mutant yields insights into senataxin post-translational modification and uncovers mutant-specific binding with a brain cytoplasmic RNA-encoded peptide. PLoS One 2013; 8:e78837. [PMID: 24244371 PMCID: PMC3823977 DOI: 10.1371/journal.pone.0078837] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 09/24/2013] [Indexed: 12/12/2022] Open
Abstract
Senataxin is a large 303 kDa protein linked to neuron survival, as recessive mutations cause Ataxia with Oculomotor Apraxia type 2 (AOA2), and dominant mutations cause amyotrophic lateral sclerosis type 4 (ALS4). Senataxin contains an amino-terminal protein-interaction domain and a carboxy-terminal DNA/RNA helicase domain. In this study, we focused upon the common ALS4 mutation, L389S, by performing yeast two-hybrid screens of a human brain expression library with control senataxin or L389S senataxin as bait. Interacting clones identified from the two screens were collated, and redundant hits and false positives subtracted to yield a set of 13 protein interactors. Among these hits, we discovered a highly specific and reproducible interaction of L389S senataxin with a peptide encoded by the antisense sequence of a brain-specific non-coding RNA, known as BCYRN1. We further found that L389S senataxin interacts with other proteins containing regions of conserved homology with the BCYRN1 reverse complement-encoded peptide, suggesting that such aberrant protein interactions may contribute to L389S ALS4 disease pathogenesis. As the yeast two-hybrid screen also demonstrated senataxin self-association, we confirmed senataxin dimerization via its amino-terminal binding domain and determined that the L389S mutation does not abrogate senataxin self-association. Finally, based upon detection of interactions between senataxin and ubiquitin-SUMO pathway modification enzymes, we examined senataxin for the presence of ubiquitin and SUMO monomers, and observed this post-translational modification. Our senataxin protein interaction study reveals a number of features of senataxin biology that shed light on senataxin normal function and likely on senataxin molecular pathology in ALS4.
Collapse
Affiliation(s)
- Craig L. Bennett
- Comparative Genomics Centre, School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Queensland, Australia
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
| | - Yingzhang Chen
- Department of Pediatrics, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Marissa Vignali
- Department of Genome Sciences, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Russell S. Lo
- Department of Genome Sciences, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Amanda G. Mason
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
| | - Asli Unal
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
| | - Nabiha P. Huq Saifee
- Department of Pharmacology, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Stanley Fields
- Department of Genome Sciences, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Albert R. La Spada
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
- Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, California, United States of America
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
- Rady Children’s Hospital, La Jolla, California, United States of America
| |
Collapse
|
28
|
Davis MY, Keene CD, Swanson PD, Sheehy C, Bird TD. Novel mutations in ataxia telangiectasia and AOA2 associated with prolonged survival. J Neurol Sci 2013; 335:134-8. [PMID: 24090759 DOI: 10.1016/j.jns.2013.09.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 08/16/2013] [Accepted: 09/10/2013] [Indexed: 12/23/2022]
Abstract
Ataxia telangiectasia (AT) and ataxia oculomotor apraxia type 2 (AOA2) are autosomal recessive ataxias caused by mutations in genes involved in maintaining DNA integrity. Lifespan in AT is greatly shortened (20s-30s) due to increased susceptibility to malignancies (leukemia/lymphoma). Lifespan in AOA2 is uncertain. We describe a woman with variant AT with two novel mutations in ATM (IVS14+2T>G and 5825C>T, p.A1942V) who died at age 48 with pancreatic adenocarcinoma. Her mutations are associated with an unusually long life for AT and with a cancer rarely associated with that disease. We also describe two siblings with AOA2, heterozygous for two novel mutations in senataxin (3 bp deletion c.343-345 and 1398T>G, p.I466M) who have survived into their 70s, allowing us to characterize the longitudinal course of AOA2. In contrast to AT, we show that persons with AOA2 can experience a prolonged lifespan with considerable motor disability.
Collapse
Affiliation(s)
- Marie Y Davis
- Department of Neurology, University of Washington, Seattle, WA, United States
| | | | | | | | | |
Collapse
|
29
|
Lavin MF, Yeo AJ, Becherel OJ. Senataxin protects the genome: Implications for neurodegeneration and other abnormalities. Rare Dis 2013; 1:e25230. [PMID: 25003001 PMCID: PMC3927485 DOI: 10.4161/rdis.25230] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/31/2013] [Indexed: 11/29/2022] Open
Abstract
Ataxia oculomotor apraxia type 2 (AOA2) is a rare autosomal recessive disorder characterized by cerebellar atrophy, peripheral neuropathy, loss of Purkinje cells and elevated α-fetoprotein. AOA2 is caused by mutations in the SETX gene that codes for the high molecular weight protein senataxin. Mutations in this gene also cause dominant neurodegenerative disorders. Similar to that observed for other autosomal recessive ataxias, this protein protects the integrity of the genome against oxidative and other forms of DNA damage to reduce the risk of neurodegeneration. Senataxin functions in transcription termination and RNA splicing and it has been shown to resolve RNA/DNA hybrids (R-loops) that arise at transcription pause sites or when transcription is blocked. Recent data suggest that this protein functions at the interface between transcription and DNA replication to minimise the risk of collision and maintain genome stability. Our recent data using SETX gene-disrupted mice revealed that male mice were defective in spermatogenesis and were infertile. DNA double strand-breaks persisted throughout meiosis and crossing-over failed in SETX mutant mice. These changes can be explained by the accumulation of R-loops, which interfere with Holiday junctions and crossing-over. We also showed that senataxin was localized to the XY body in pachytene cells and was involved in transcriptional silencing of these chromosomes. While the defect in meiotic recombination was striking in these animals, there was no evidence of neurodegeneration as observed in AOA2 patients. We discuss here potentially different roles for senataxin in proliferating and post-mitotic cells.
Collapse
Affiliation(s)
- Martin F Lavin
- Queensland Institute of Medical Research; Radiation Biology and Oncology; Brisbane, QLD, Australia ; University of Queensland Centre for Clinical Research; Herston, QLD, Australia
| | - Abrey J Yeo
- Queensland Institute of Medical Research; Radiation Biology and Oncology; Brisbane, QLD, Australia ; School of Medicine; University of Queensland; Herston, QLD, Australia
| | - Olivier J Becherel
- Queensland Institute of Medical Research; Radiation Biology and Oncology; Brisbane, QLD, Australia ; School of Chemistry & Molecular Biosciences; University of Queensland; St. Lucia, QLD, Australia
| |
Collapse
|
30
|
Reynolds JJ, Stewart GS. A single strand that links multiple neuropathologies in human disease. ACTA ACUST UNITED AC 2013; 136:14-27. [PMID: 23365091 DOI: 10.1093/brain/aws310] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The development of the human central nervous system is a complex process involving highly coordinated periods of neuronal proliferation, migration and differentiation. Disruptions in these neurodevelopmental processes can result in microcephaly, a neuropathological disorder characterized by a reduction in skull circumference and total brain volume, whereas a failure to maintain neuronal health in the adult brain can lead to progressive neurodegeneration. Defects in the cellular pathways that detect and repair DNA damage are a common cause of both these neuropathologies and are associated with a growing number of hereditary human disorders. In particular, defects in the repair of DNA single strand breaks, one of the most commonly occurring types of DNA lesion, have been associated with three neuropathological diseases: ataxia oculomotor apraxia 1, spinocerebellar ataxia with neuronal neuropathy 1 and microcephaly, early-onset, intractable seizures and developmental delay. A striking similarity between these three human diseases is that they are all caused by mutations in DNA end processing factors, suggesting that a particularly crucial stage of DNA single strand break repair is the repair of breaks with 'damaged' termini. Additionally all three disorders lack any extraneurological symptoms, such as immunodeficiency and cancer predisposition, which are typically found in other human diseases associated with defective DNA repair. However despite these similarities, two of these disorders present with progressive cerebellar degeneration, whereas the third presents with severe microcephaly. This review discusses the molecular defects behind these disorders and presents several hypotheses based on current literature on a number of important questions, in particular, how do mutations in different end processing factors within the same DNA repair pathway lead to such different neuropathologies?
Collapse
Affiliation(s)
- John J Reynolds
- School of Cancer Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | | |
Collapse
|
31
|
Cozzolino M, Pesaresi MG, Gerbino V, Grosskreutz J, Carrì MT. Amyotrophic lateral sclerosis: new insights into underlying molecular mechanisms and opportunities for therapeutic intervention. Antioxid Redox Signal 2012; 17:1277-330. [PMID: 22413952 DOI: 10.1089/ars.2011.4328] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recent years have witnessed a renewed interest in the pathogenic mechanisms of amyotrophic lateral sclerosis (ALS), a late-onset progressive degeneration of motor neurons. The discovery of new genes associated with the familial form of the disease, along with a deeper insight into pathways already described for this disease, has led scientists to reconsider previous postulates. While protein misfolding, mitochondrial dysfunction, oxidative damage, defective axonal transport, and excitotoxicity have not been dismissed, they need to be re-examined as contributors to the onset or progression of ALS in the light of the current knowledge that the mutations of proteins involved in RNA processing, apparently unrelated to the previous "old partners," are causative of the same phenotype. Thus, newly envisaged models and tools may offer unforeseen clues on the etiology of this disease and hopefully provide the key to treatment.
Collapse
|