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Reyes-Ábalos AL, Álvarez-Zabaleta M, Olivera-Bravo S, Di Tomaso MV. Astrocyte DNA damage and response upon acute exposure to ethanol and corticosterone. FRONTIERS IN TOXICOLOGY 2024; 5:1277047. [PMID: 38259729 PMCID: PMC10800529 DOI: 10.3389/ftox.2023.1277047] [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: 08/13/2023] [Accepted: 12/11/2023] [Indexed: 01/24/2024] Open
Abstract
Introduction: Astrocytes are the glial cells responsible for brain homeostasis, but if injured, they could damage neural cells even deadly. Genetic damage, DNA damage response (DDR), and its downstream cascades are dramatic events poorly studied in astrocytes. Hypothesis and methods: We propose that 1 h of 400 mmol/L ethanol and/or 1 μmol/L corticosterone exposure of cultured hippocampal astrocytes damages DNA, activating the DDR and eliciting functional changes. Immunolabeling against γH2AX (chromatin DNA damage sites), cyclin D1 (cell cycle control), nuclear (base excision repair, BER), and cytoplasmic (anti-inflammatory functions) APE1, ribosomal nucleolus proteins together with GFAP and S100β plus scanning electron microscopy studies of the astrocyte surface were carried out. Results: Data obtained indicate significant DNA damage, immediate cell cycle arrest, and BER activation. Changes in the cytoplasmic signals of cyclin D1 and APE1, nucleolus number, and membrane-attached vesicles strongly suggest a reactivity like astrocyte response without significant morphological changes. Discussion: Obtained results uncover astrocyte genome immediate vulnerability and DDR activation, plus a functional response that might in part, be signaled through extracellular vesicles, evidencing the complex influence that astrocytes may have on the CNS even upon short-term aggressions.
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Affiliation(s)
- Ana Laura Reyes-Ábalos
- Departamento de Genética, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Magdalena Álvarez-Zabaleta
- Departamento de Genética, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | | | - María Vittoria Di Tomaso
- Departamento de Genética, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
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2
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Ruszel KP, Zalewski DP, Stępniewski A, Gałkowski D, Bogucki J, Feldo M, Płachno BJ, Kocki J, Bogucka-Kocka A. Next-Generation Sequencing in the Assessment of the Transcriptomic Landscape of DNA Damage Repair Genes in Abdominal Aortic Aneurysm, Chronic Venous Disease and Lower Extremity Artery Disease. Int J Mol Sci 2022; 24:ijms24010551. [PMID: 36614026 PMCID: PMC9820637 DOI: 10.3390/ijms24010551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/17/2022] [Accepted: 12/21/2022] [Indexed: 12/31/2022] Open
Abstract
Vascular diseases are one of the most common causes of death and morbidity. Lower extremity artery disease (LEAD), abdominal aortic aneurysm (AAA) and chronic venous disease (CVD) belong to this group of conditions and exhibit various presentations and courses; thus, there is an urgent need for revealing new biomarkers for monitoring and potential treatment. Next-generation sequencing of mRNA allows rapid and detailed transcriptome analysis, allowing us to pinpoint the most pronounced differences between the mRNA expression profiles of vascular disease patients. Comparison of expression data of 519 DNA-repair-related genes obtained from mRNA next-generation sequencing revealed significant transcriptomic marks characterizing AAA, CVD and LEAD. Statistical, gene set enrichment analysis (GSEA), gene ontology (GO) and literature analyses were applied and highlighted many DNA repair and accompanying processes, such as cohesin functions, oxidative stress, homologous recombination, ubiquitin turnover, chromatin remodelling and DNA double-strand break repair. Surprisingly, obtained data suggest the contribution of genes engaged in the regulatory function of DNA repair as a key component that could be used to distinguish between analyzed conditions. DNA repair-related genes depicted in the presented study as dysregulated in AAA, CVD and LEAD could be utilized in the design of new biomarkers or therapies associated with these diseases.
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Affiliation(s)
- Karol P. Ruszel
- Department of Clinical Genetics, Chair of Medical Genetics, Medical University of Lublin, 11 Radziwiłłowska St., 20-080 Lublin, Poland
- Correspondence: ; Tel.: +48-81-448-6610
| | - Daniel P. Zalewski
- Chair and Department of Biology and Genetics, Medical University of Lublin, 4a Chodźki St., 20-093 Lublin, Poland
| | - Andrzej Stępniewski
- Ecotech Complex Analytical and Programme Centre for Advanced Environmentally Friendly Technologies, University of Marie Curie-Skłodowska, 39 Głęboka St., 20-612 Lublin, Poland
| | - Dariusz Gałkowski
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, One Robert Wood Johnson Place, New Brunswick, NJ 08903, USA
| | - Jacek Bogucki
- Chair and Department of Organic Chemistry, Medical University of Lublin, 4a Chodźki St., 20-093 Lublin, Poland
| | - Marcin Feldo
- Chair and Department of Vascular Surgery and Angiology, Medical University of Lublin, 11 Staszica St., 20-081 Lublin, Poland
| | - Bartosz J. Płachno
- Department of Plant Cytology and Embryology, Institute of Botany, Faculty of Biology, Jagiellonian University in Kraków, 9 Gronostajowa St., 30-387 Kraków, Poland
| | - Janusz Kocki
- Department of Clinical Genetics, Chair of Medical Genetics, Medical University of Lublin, 11 Radziwiłłowska St., 20-080 Lublin, Poland
| | - Anna Bogucka-Kocka
- Chair and Department of Biology and Genetics, Medical University of Lublin, 4a Chodźki St., 20-093 Lublin, Poland
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Feltes BC. Architects meets Repairers: The interplay between homeobox genes and DNA repair. DNA Repair (Amst) 2018; 73:34-48. [PMID: 30448208 DOI: 10.1016/j.dnarep.2018.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 10/30/2018] [Indexed: 02/07/2023]
Abstract
Homeobox genes are widely considered the major protagonists of embryonic development and tissue formation. For the past decades, it was established that the deregulation of these genes is intimately related to developmental abnormalities and a broad range of diseases in adults. Since the proper regulation and expression of homeobox genes are necessary for a successful developmental program and tissue function, their relation to DNA repair mechanisms become a necessary discussion. However, important as it is, studies focused on the interplay between homeobox genes and DNA repair are scarce, and there is no critical discussion on the subject. Hence, in this work, I aim to provide the first review of the current knowledge of the interplay between homeobox genes and DNA repair mechanisms, and offer future perspectives on this, yet, young ground for new researches. Critical discussion is conducted, together with a careful assessment of each reviewed topic.
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Affiliation(s)
- Bruno César Feltes
- Institute of Informatics, Department of Theoretical Informatics, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
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4
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Epanchintsev A, Costanzo F, Rauschendorf MA, Caputo M, Ye T, Donnio LM, Proietti-de-Santis L, Coin F, Laugel V, Egly JM. Cockayne's Syndrome A and B Proteins Regulate Transcription Arrest after Genotoxic Stress by Promoting ATF3 Degradation. Mol Cell 2017; 68:1054-1066.e6. [PMID: 29225035 DOI: 10.1016/j.molcel.2017.11.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/09/2017] [Accepted: 11/08/2017] [Indexed: 12/21/2022]
Abstract
Cockayne syndrome (CS) is caused by mutations in CSA and CSB. The CSA and CSB proteins have been linked to both promoting transcription-coupled repair and restoring transcription following DNA damage. We show that UV stress arrests transcription of approximately 70% of genes in CSA- or CSB-deficient cells due to the constitutive presence of ATF3 at CRE/ATF sites. We found that CSB, CSA/DDB1/CUL4A, and MDM2 were essential for ATF3 ubiquitination and degradation by the proteasome. ATF3 removal was concomitant with the recruitment of RNA polymerase II and the restart of transcription. Preventing ATF3 ubiquitination by mutating target lysines prevented recovery of transcription and increased cell death following UV treatment. Our data suggest that the coordinate action of CSA and CSB, as part of the ubiquitin/proteasome machinery, regulates the recruitment timing of DNA-binding factors and provide explanations about the mechanism of transcription arrest following genotoxic stress.
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Affiliation(s)
- Alexey Epanchintsev
- IGBMC, Department of Functional Genomics and Cancer, Equipe Labellisée Ligue 2014, CNRS/INSERM/University of Strasbourg, BP 163, 67404 Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67404 Illkirch, France
| | - Federico Costanzo
- IGBMC, Department of Functional Genomics and Cancer, Equipe Labellisée Ligue 2014, CNRS/INSERM/University of Strasbourg, BP 163, 67404 Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67404 Illkirch, France
| | - Marc-Alexander Rauschendorf
- IGBMC, Department of Functional Genomics and Cancer, Equipe Labellisée Ligue 2014, CNRS/INSERM/University of Strasbourg, BP 163, 67404 Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67404 Illkirch, France
| | - Manuela Caputo
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, 01100 Viterbo, Italy
| | - Tao Ye
- IGBMC, Department of Functional Genomics and Cancer, Equipe Labellisée Ligue 2014, CNRS/INSERM/University of Strasbourg, BP 163, 67404 Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67404 Illkirch, France
| | - Lise-Marie Donnio
- IGBMC, Department of Functional Genomics and Cancer, Equipe Labellisée Ligue 2014, CNRS/INSERM/University of Strasbourg, BP 163, 67404 Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67404 Illkirch, France
| | - Luca Proietti-de-Santis
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, 01100 Viterbo, Italy
| | - Frederic Coin
- IGBMC, Department of Functional Genomics and Cancer, Equipe Labellisée Ligue 2014, CNRS/INSERM/University of Strasbourg, BP 163, 67404 Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67404 Illkirch, France
| | - Vincent Laugel
- Laboratory of Medical Genetics, University of Strasbourg, 11 rue Humann, 67000 Strasbourg, France; Department of Pediatric Neurology, Strasbourg University Hospital, Avenue Moliere, 67098 Strasbourg Cedex, France
| | - Jean-Marc Egly
- IGBMC, Department of Functional Genomics and Cancer, Equipe Labellisée Ligue 2014, CNRS/INSERM/University of Strasbourg, BP 163, 67404 Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67404 Illkirch, France.
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5
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Su Y, Yang C, Zhang Z. The Association Between XPG Gene Polymorphism and Gastric Cancer Risk. Genet Test Mol Biomarkers 2017; 21:619-624. [PMID: 28832189 DOI: 10.1089/gtmb.2017.0056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
PURPOSE Studies exploring the association between the Xeroderma pigmentosum group G (XPG) gene polymorphisms and gastric cancer (GC) risk provide conflicting findings. Thus, this meta-analysis was performed. MATERIALS AND METHODS The PubMed and EMBASE databases were comprehensively searched to identify studies for the inclusion in the meta-analysis. The strength of the association was evaluated by calculating pooled odds ratios and 95% confidence intervals. RESULTS Nine case-control studies involving 3540 cases and 3953 controls were included in the meta-analysis, which revealed that the XPG rs751402 polymorphism is positively associated with GC risk and could be viewed as a risk factor of GC in three genetic models. CONCLUSION The XPG gene rs751402 polymorphism is associated with an increased risk of GC in Chinese Han populations. This finding should be verified by larger studies that include additional ethnic groups.
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Affiliation(s)
- Yanyan Su
- Department of General Surgery, Hangzhou Red Cross Hospital/Zhe Jiang Chinese Medicine and Western Medicine Integrated Hospital , Hangzhou, China
| | - Chong Yang
- Department of General Surgery, Hangzhou Red Cross Hospital/Zhe Jiang Chinese Medicine and Western Medicine Integrated Hospital , Hangzhou, China
| | - Zongxiang Zhang
- Department of General Surgery, Hangzhou Red Cross Hospital/Zhe Jiang Chinese Medicine and Western Medicine Integrated Hospital , Hangzhou, China
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6
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Hijazi H, Salih M, Hamad M, Hassan H, Salih S, Mohamed K, Mukhtar M, Karrar Z, Ansari S, Ibrahim N, Alkuraya F. Pellagra-like condition is xeroderma pigmentosum/Cockayne syndrome complex and niacin confers clinical benefit. Clin Genet 2013; 87:56-61. [DOI: 10.1111/cge.12325] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/19/2013] [Accepted: 11/19/2013] [Indexed: 11/28/2022]
Affiliation(s)
- H. Hijazi
- Department of Genetics; King Faisal Specialist Hospital and Research Center; Riyadh Saudi Arabia
| | | | | | - H.H. Hassan
- Department of Radiology; King Khalid University Hospital and College of Medicine, King Saud University; Riyadh Saudi Arabia
| | - S.B.M. Salih
- Department of Pediatrics, Mafraq Hospital; Abu Dhabi United Arab Emirates
| | - K.A. Mohamed
- Department of Pediatrics (Neurology), Sheikh Khalifa Medical City; Abu Dhabi United Arab Emirates
| | - M.M. Mukhtar
- Institute of Endemic Diseases, Faculty of Medicine
| | - Z.A. Karrar
- Department of Pediatrics and Child Health, Faculty of Medicine; University of Khartoum; Khartoum Sudan
| | - S. Ansari
- Department of Genetics; King Faisal Specialist Hospital and Research Center; Riyadh Saudi Arabia
| | - N. Ibrahim
- Department of Genetics; King Faisal Specialist Hospital and Research Center; Riyadh Saudi Arabia
| | - F.S. Alkuraya
- Department of Genetics; King Faisal Specialist Hospital and Research Center; Riyadh Saudi Arabia
- Department of Anatomy and Cell Biology, College of Medicine; Alfaisal University; Riyadh Saudi Arabia
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7
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Brooks PJ. Blinded by the UV light: how the focus on transcription-coupled NER has distracted from understanding the mechanisms of Cockayne syndrome neurologic disease. DNA Repair (Amst) 2013; 12:656-71. [PMID: 23683874 PMCID: PMC4240003 DOI: 10.1016/j.dnarep.2013.04.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cockayne syndrome (CS) is a devastating neurodevelopmental disorder, with growth abnormalities, progeriod features, and sun sensitivity. CS is typically considered to be a DNA repair disorder, since cells from CS patients have a defect in transcription-coupled nucleotide excision repair (TC-NER). However, cells from UV-sensitive syndrome patients also lack TC-NER, but these patients do not suffer from the neurologic and other abnormalities that CS patients do. Also, the neurologic abnormalities that affect CS patients (CS neurologic disease) are qualitatively different from those seen in NER-deficient XP patients. Therefore, the TC-NER defect explains the sun sensitive phenotype common to both CS and UVsS, but cannot explain CS neurologic disease. However, as CS neurologic disease is of much greater clinical significance than the sun sensitivity, there is a pressing need to understand its molecular basis. While there is evidence for defective repair of oxidative DNA damage and mitochondrial abnormalities in CS cells, here I propose that the defects in transcription by both RNA polymerases I and II that have been documented in CS cells provide a better explanation for many of the severe growth and neurodevelopmental defects in CS patients than defective DNA repair. The implications of these ideas for interpreting results from mouse models of CS, and for the development of treatments and therapies for CS patients are discussed.
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Affiliation(s)
- P J Brooks
- Laboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, NIH, 5625 Fishers Lane, 3S-32, Bethesda, MD 20892, USA.
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8
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Mason PA, Cox LS. The role of DNA exonucleases in protecting genome stability and their impact on ageing. AGE (DORDRECHT, NETHERLANDS) 2012; 34:1317-1340. [PMID: 21948156 PMCID: PMC3528374 DOI: 10.1007/s11357-011-9306-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 08/19/2011] [Indexed: 05/30/2023]
Abstract
Exonucleases are key enzymes involved in many aspects of cellular metabolism and maintenance and are essential to genome stability, acting to cleave DNA from free ends. Exonucleases can act as proof-readers during DNA polymerisation in DNA replication, to remove unusual DNA structures that arise from problems with DNA replication fork progression, and they can be directly involved in repairing damaged DNA. Several exonucleases have been recently discovered, with potentially critical roles in genome stability and ageing. Here we discuss how both intrinsic and extrinsic exonuclease activities contribute to the fidelity of DNA polymerases in DNA replication. The action of exonucleases in processing DNA intermediates during normal and aberrant DNA replication is then assessed, as is the importance of exonucleases in repair of double-strand breaks and interstrand crosslinks. Finally we examine how exonucleases are involved in maintenance of mitochondrial genome stability. Throughout the review, we assess how nuclease mutation or loss predisposes to a range of clinical diseases and particularly ageing.
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Affiliation(s)
- Penelope A. Mason
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU UK
| | - Lynne S. Cox
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU UK
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9
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Active DNA demethylation and DNA repair. Differentiation 2008; 77:1-11. [PMID: 19281759 DOI: 10.1016/j.diff.2008.09.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 06/19/2008] [Accepted: 07/07/2008] [Indexed: 12/17/2022]
Abstract
DNA methylation on cytosine is an epigenetic modification and is essential for gene regulation and genome stability in vertebrates. Traditionally DNA methylation was considered as the most stable of all heritable epigenetic marks. However, it has become clear that DNA methylation is reversible by enzymatic "active" DNA demethylation, with examples in plant cells, animal development and immune cells. It emerges that "pruning" of methylated cytosines by active DNA demethylation is an important determinant for the DNA methylation signature of a cell. Work in plants and animals shows that demethylation occurs by base excision and nucleotide excision repair. Far from merely protecting genomic integrity from environmental insult, DNA repair is therefore at the heart of an epigenetic activation process.
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10
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Affiliation(s)
- A M R Taylor
- CR-UK Institute for Cancer Studies, University of Birmingham.
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11
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The 8,5'-cyclopurine-2'-deoxynucleosides: candidate neurodegenerative DNA lesions in xeroderma pigmentosum, and unique probes of transcription and nucleotide excision repair. DNA Repair (Amst) 2008; 7:1168-79. [PMID: 18495558 DOI: 10.1016/j.dnarep.2008.03.016] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
It is a commonly held view that oxidatively induced DNA lesions are repaired by the base excision repair (BER) pathway, whereas DNA lesions induced by UV light and other "bulky" chemical adducts are repaired by the nucleotide excision repair (NER) pathway. While this distinction is generally accurate, the 8,5'-cyclopurine deoxynucleosides represent an important exception, in that they are formed in DNA by the hydroxyl radical, but are specifically repaired by NER, not by BER. They are also strong blocks to nucleases and polymerases, including RNA polymerase II in human cells. In this review, I will discuss the evidence that these lesions are in part responsible for the neurodegeneration that occurs in some XP patients, and what additional evidence would be necessary to prove such a role. I will also consider other DNA lesions that might be involved in XP neurologic disease. Finally, I will also discuss how our recent studies of these lesions have generated novel insights into the process of transcriptional mutagenesis in human cells, as well as the value of studying these lesions not only for a better understanding of NER but also for other aspects of human health and disease.
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12
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Lohman TM, Tomko EJ, Wu CG. Non-hexameric DNA helicases and translocases: mechanisms and regulation. Nat Rev Mol Cell Biol 2008; 9:391-401. [PMID: 18414490 DOI: 10.1038/nrm2394] [Citation(s) in RCA: 268] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Helicases and nucleic acid translocases are motor proteins that have essential roles in nearly all aspects of nucleic acid metabolism, ranging from DNA replication to chromatin remodelling. Fuelled by the binding and hydrolysis of nucleoside triphosphates, helicases move along nucleic acid filaments and separate double-stranded DNA into their complementary single strands. Recent evidence indicates that the ability to simply translocate along single-stranded DNA is, in many cases, insufficient for helicase activity. For some of these enzymes, self assembly and/or interactions with accessory proteins seem to regulate their translocase and helicase activities.
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Affiliation(s)
- Timothy M Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, Missouri 63110, USA.
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13
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An abundant evolutionarily conserved CSB-PiggyBac fusion protein expressed in Cockayne syndrome. PLoS Genet 2008; 4:e1000031. [PMID: 18369450 PMCID: PMC2268245 DOI: 10.1371/journal.pgen.1000031] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Accepted: 02/11/2008] [Indexed: 12/27/2022] Open
Abstract
Cockayne syndrome (CS) is a devastating progeria most often caused by mutations in the CSB gene encoding a SWI/SNF family chromatin remodeling protein. Although all CSB mutations that cause CS are recessive, the complete absence of CSB protein does not cause CS. In addition, most CSB mutations are located beyond exon 5 and are thought to generate only C-terminally truncated protein fragments. We now show that a domesticated PiggyBac-like transposon PGBD3, residing within intron 5 of the CSB gene, functions as an alternative 3′ terminal exon. The alternatively spliced mRNA encodes a novel chimeric protein in which CSB exons 1–5 are joined in frame to the PiggyBac transposase. The resulting CSB-transposase fusion protein is as abundant as CSB protein itself in a variety of human cell lines, and continues to be expressed by primary CS cells in which functional CSB is lost due to mutations beyond exon 5. The CSB-transposase fusion protein has been highly conserved for at least 43 Myr since the divergence of humans and marmoset, and appears to be subject to selective pressure. The human genome contains over 600 nonautonomous PGBD3-related MER85 elements that were dispersed when the PGBD3 transposase was last active at least 37 Mya. Many of these MER85 elements are associated with genes which are involved in neuronal development, and are known to be regulated by CSB. We speculate that the CSB-transposase fusion protein has been conserved for host antitransposon defense, or to modulate gene regulation by MER85 elements, but may cause CS in the absence of functional CSB protein. For reasons that are still unclear, genetic defects in DNA repair can cause diseases that resemble aspects of premature ageing (“segmental progerias”). Cockayne syndrome (CS) is a particularly devastating progeria most commonly caused by mutations in the CSB chromatin remodeling gene. About 43 million years ago, before humans diverged from marmosets, one of the last PiggyBac transposable elements to invade the human lineage landed within intron 5 of the 21 exon CSB gene. As a result, the CSB locus now encodes two equally abundant proteins generated by alternative mRNA splicing: the original full length CSB protein, and a novel CSB-PiggyBac fusion protein in which the N-terminus of CSB is fused to the complete PiggyBac transposase. Conservation of the CSB-PiggyBac fusion protein since marmoset suggests that it is normally beneficial, demonstrating once again that “selfish” transposable elements can be exploited or “domesticated” by the host. More importantly, almost all CSB mutations that cause CS continue to make the CSB-PiggyBac fusion protein, whereas a mutation that compromises both does not cause CS. Thus the fusion protein which is beneficial in the presence of functional CSB may be harmful in its absence. This may help clarify the cause of CS and other progerias.
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Do all of the neurologic diseases in patients with DNA repair gene mutations result from the accumulation of DNA damage? DNA Repair (Amst) 2008; 7:834-48. [PMID: 18339586 DOI: 10.1016/j.dnarep.2008.01.017] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 01/23/2008] [Indexed: 01/01/2023]
Abstract
The classic model for neurodegeneration due to mutations in DNA repair genes holds that DNA damage accumulates in the absence of repair, resulting in the death of neurons. This model was originally put forth to explain the dramatic loss of neurons observed in patients with xeroderma pigmentosum neurologic disease, and is likely to be valid for other neurodegenerative diseases due to mutations in DNA repair genes. However, in trichiothiodystrophy (TTD), Aicardi-Goutières syndrome (AGS), and Cockayne syndrome (CS), abnormal myelin is the most prominent neuropathological feature. Myelin is synthesized by specific types of glial cells called oligodendrocytes. In this review, we focus on new studies that illustrate two disease mechanisms for myelin defects resulting from mutations in DNA repair genes, both of which are fundamentally different than the classic model described above. First, studies using the TTD mouse model indicate that TFIIH acts as a co-activator for thyroid hormone-dependent gene expression in the brain, and that a causative XPD mutation in TTD results in reduction of this co-activator function and a dysregulation of myelin-related gene expression. Second, in AGS, which is caused by mutations in either TREX1 or RNASEH2, recent evidence indicates that failure to degrade nucleic acids produced during S-phase triggers activation of the innate immune system, resulting in myelin defects and calcification of the brain. Strikingly, both myelin defects and brain calcification are both prominent features of CS neurologic disease. The similar neuropathology in CS and AGS seems unlikely to be due to the loss of a common DNA repair function, and based on the evidence in the literature, we propose that vascular abnormalities may be part of the mechanism that is common to both diseases. In summary, while the classic DNA damage accumulation model is applicable to the neuronal death due to defective DNA repair, the myelination defects and brain calcification seem to be better explained by quite different mechanisms. We discuss the implications of these different disease mechanisms for the rational development of treatments and therapies.
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15
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Simonatto M, Latella L, Puri PL. DNA damage and cellular differentiation: more questions than responses. J Cell Physiol 2007; 213:642-8. [PMID: 17894406 DOI: 10.1002/jcp.21275] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Studies on DNA damage responses in proliferating cells have revealed the relationship between sensing and repair of the DNA lesions and the regulation of the cell cycle, leading to the discovery and molecular characterization of the DNA damage-activated cell cycle checkpoints. Much less is known about the DNA damage response in progenitors of differentiated cells, in which cell cycle arrest is a critical signal to trigger the differentiation program, and in terminally differentiated cells, which are typically post-mitotic. How DNA lesions are detected, processed and repaired in these cells, the functional impact of DNA damage on transcription of differentiation-specific genes, how these events are coordinated at the molecular level, the consequence of defective DNA damage response on tissue-specific functions and its potential relationship with age-related diseases are currently open questions. In particular the biological complexity inherent to the global genome reprogramming of tissue progenitors, such as embryonic or adult stem cells, suggests the importance of an accurate DNA damage response at the transcription level in these cells to ensure the genomic integrity of regenerating tissues.
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Affiliation(s)
- Marta Simonatto
- Dulbecco Telethon Institute, Fondazione Santa Lucia/EBRI, Roma, Italy
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