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Ascenção C, Sims JR, Dziubek A, Comstock W, Fogarty EA, Badar J, Freire R, Grimson A, Weiss RS, Cohen PE, Smolka MB. A TOPBP1 allele causing male infertility uncouples XY silencing dynamics from sex body formation. eLife 2024; 12:RP90887. [PMID: 38391183 PMCID: PMC10942628 DOI: 10.7554/elife.90887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024] Open
Abstract
Meiotic sex chromosome inactivation (MSCI) is a critical feature of meiotic prophase I progression in males. While the ATR kinase and its activator TOPBP1 are key drivers of MSCI within the specialized sex body (SB) domain of the nucleus, how they promote silencing remains unclear given their multifaceted meiotic functions that also include DNA repair, chromosome synapsis, and SB formation. Here we report a novel mutant mouse harboring mutations in the TOPBP1-BRCT5 domain. Topbp1B5/B5 males are infertile, with impaired MSCI despite displaying grossly normal events of early prophase I, including synapsis and SB formation. Specific ATR-dependent events are disrupted, including phosphorylation and localization of the RNA:DNA helicase Senataxin. Topbp1B5/B5 spermatocytes initiate, but cannot maintain ongoing, MSCI. These findings reveal a non-canonical role for the ATR-TOPBP1 signaling axis in MSCI dynamics at advanced stages in pachynema and establish the first mouse mutant that separates ATR signaling and MSCI from SB formation.
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Affiliation(s)
- Carolline Ascenção
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Jennie R Sims
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Alexis Dziubek
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - William Comstock
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Elizabeth A Fogarty
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Jumana Badar
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Raimundo Freire
- Fundación Canaria del Instituto de Investigación Sanitaria de Canarias (FIISC), Unidad de Investigación, Hospital Universitario de CanariasSanta Cruz de TenerifeSpain
- Instituto de Tecnologías Biomédicas, Universidad de La LagunaLa LagunaSpain
- Universidad Fernando Pessoa CanariasLas Palmas de Gran CanariaSpain
| | - Andrew Grimson
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Robert S Weiss
- Department of Biomedical Sciences, Cornell UniversityIthacaUnited States
| | - Paula E Cohen
- Department of Biomedical Sciences, Cornell UniversityIthacaUnited States
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
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2
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Ascencao CFR, Sims JR, Dziubek A, Comstock W, Fogarty EA, Badar J, Freire R, Grimson A, Weiss RS, Cohen PE, Smolka M. A TOPBP1 Allele Causing Male Infertility Uncouples XY Silencing Dynamics From Sex Body Formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.31.543071. [PMID: 37398453 PMCID: PMC10312512 DOI: 10.1101/2023.05.31.543071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Meiotic sex chromosome inactivation (MSCI) is a critical feature of meiotic prophase I progression in males. While the ATR kinase and its activator TOPBP1 are key drivers of MSCI within the specialized sex body (SB) domain of the nucleus, how they promote silencing remains unclear given their multifaceted meiotic functions that also include DNA repair, chromosome synapsis and SB formation. Here we report a novel mutant mouse harboring mutations in the TOPBP1-BRCT5 domain. Topbp1 B5/B5 males are infertile, with impaired MSCI despite displaying grossly normal events of early prophase I, including synapsis and SB formation. Specific ATR-dependent events are disrupted including phosphorylation and localization of the RNA:DNA helicase Senataxin. Topbp1 B5/B5 spermatocytes initiate, but cannot maintain ongoing, MSCI. These findings reveal a non-canonical role for the ATR-TOPBP1 signaling axis in MSCI dynamics at advanced stages in pachynema and establish the first mouse mutant that separates ATR signaling and MSCI from SB formation.
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3
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Gall-Duncan T, Luo J, Jurkovic CM, Fischer LA, Fujita K, Deshmukh AL, Harding RJ, Tran S, Mehkary M, Li V, Leib DE, Chen R, Tanaka H, Mason AG, Lévesque D, Khan M, Razzaghi M, Prasolava T, Lanni S, Sato N, Caron MC, Panigrahi GB, Wang P, Lau R, Castel AL, Masson JY, Tippett L, Turner C, Spies M, La Spada AR, Campos EI, Curtis MA, Boisvert FM, Faull RLM, Davidson BL, Nakamori M, Okazawa H, Wold MS, Pearson CE. Antagonistic roles of canonical and Alternative-RPA in disease-associated tandem CAG repeat instability. Cell 2023; 186:4898-4919.e25. [PMID: 37827155 PMCID: PMC11209935 DOI: 10.1016/j.cell.2023.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 06/30/2023] [Accepted: 09/09/2023] [Indexed: 10/14/2023]
Abstract
Expansions of repeat DNA tracts cause >70 diseases, and ongoing expansions in brains exacerbate disease. During expansion mutations, single-stranded DNAs (ssDNAs) form slipped-DNAs. We find the ssDNA-binding complexes canonical replication protein A (RPA1, RPA2, and RPA3) and Alternative-RPA (RPA1, RPA3, and primate-specific RPA4) are upregulated in Huntington disease and spinocerebellar ataxia type 1 (SCA1) patient brains. Protein interactomes of RPA and Alt-RPA reveal unique and shared partners, including modifiers of CAG instability and disease presentation. RPA enhances in vitro melting, FAN1 excision, and repair of slipped-CAGs and protects against CAG expansions in human cells. RPA overexpression in SCA1 mouse brains ablates expansions, coincident with decreased ATXN1 aggregation, reduced brain DNA damage, improved neuron morphology, and rescued motor phenotypes. In contrast, Alt-RPA inhibits melting, FAN1 excision, and repair of slipped-CAGs and promotes CAG expansions. These findings suggest a functional interplay between the two RPAs where Alt-RPA may antagonistically offset RPA's suppression of disease-associated repeat expansions, which may extend to other DNA processes.
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Affiliation(s)
- Terence Gall-Duncan
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Jennifer Luo
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | | | - Laura A Fischer
- Developmental Biology and Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Kyota Fujita
- Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Amit L Deshmukh
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Rachel J Harding
- Structural Genomics Consortium, University of Toronto, Toronto, ON M5G 1L7, Canada; Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Stephanie Tran
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Mustafa Mehkary
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Vanessa Li
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - David E Leib
- Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19146, USA
| | - Ran Chen
- Pediatrics, Division of Hematology and Oncology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hikari Tanaka
- Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Amanda G Mason
- Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Dominique Lévesque
- Immunology and Cell Biology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Mahreen Khan
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Mortezaali Razzaghi
- Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Tanya Prasolava
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Stella Lanni
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Nozomu Sato
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Marie-Christine Caron
- CHU de Québec-Université Laval, Oncology Division, Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec, QC, Canada
| | - Gagan B Panigrahi
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Peixiang Wang
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Rachel Lau
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | | | - Jean-Yves Masson
- CHU de Québec-Université Laval, Oncology Division, Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec, QC, Canada
| | - Lynette Tippett
- School of Psychology, University of Auckland, Auckland, New Zealand; University Research Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Clinton Turner
- Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Maria Spies
- Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Albert R La Spada
- Pathology & Laboratory Medicine, Neurology, and Biological Chemistry, University of California, Irvine School of Medicine, Irvine, CA, USA; Neurobiology & Behavior, University of California, Irvine, Irvine, CA, USA; Center for Neurotherapeutics, University of California, Irvine, Irvine, CA 92697, USA
| | - Eric I Campos
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Maurice A Curtis
- University Research Centre for Brain Research, University of Auckland, Auckland, New Zealand; Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | | | - Richard L M Faull
- University Research Centre for Brain Research, University of Auckland, Auckland, New Zealand; Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | - Beverly L Davidson
- Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19146, USA
| | - Masayuki Nakamori
- Neurology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hitoshi Okazawa
- Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Marc S Wold
- Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Christopher E Pearson
- Genetics & Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada; Structural Genomics Consortium, University of Toronto, Toronto, ON M5G 1L7, Canada.
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Chevarin M, Alcantara D, Albuisson J, Collonge-Rame MA, Populaire C, Selmani Z, Baurand A, Sawka C, Bertolone G, Callier P, Duffourd Y, Jonveaux P, Bignon YJ, Coupier I, Cornelis F, Cordier C, Mozelle-Nivoix M, Rivière JB, Kuentz P, Thauvin C, Boidot R, Ghiringhelli F, O'Driscoll M, Faivre L, Nambot S. The "extreme phenotype approach" applied to male breast cancer allows the identification of rare variants of ATR as potential breast cancer susceptibility alleles. Oncotarget 2023; 14:111-125. [PMID: 36749285 PMCID: PMC9904323 DOI: 10.18632/oncotarget.28358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 01/23/2023] [Indexed: 02/08/2023] Open
Abstract
In oncogenetics, some patients could be considered as "extreme phenotypes", such as those with very early onset presentation or multiple primary malignancies, unusually high numbers of cancers of the same spectrum or rare cancer types in the same parental branch. For these cases, a genetic predisposition is very likely, but classical candidate gene panel analyses often and frustratingly remains negative. In the framework of the EX2TRICAN project, exploring unresolved extreme cancer phenotypes, we applied exome sequencing on rare familial cases with male breast cancer, identifying a novel pathogenic variant of ATR (p.Leu1808*). ATR has already been suspected as being a predisposing gene to breast cancer in women. We next identified 3 additional ATR variants in a cohort of both male and female with early onset and familial breast cancers (c.7762-2A>C; c.2078+1G>A; c.1A>G). Further molecular and cellular investigations showed impacts on transcripts for variants affecting splicing sites and reduction of ATR expression and phosphorylation of the ATR substrate CHEK1. This work further demonstrates the interest of an extended genetic analysis such as exome sequencing to identify very rare variants that can play a role in cancer predisposition in extreme phenotype cancer cases unexplained by classical cancer gene panels testing.
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Affiliation(s)
- Martin Chevarin
- Inserm UMR 1231 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
- Unité Fonctionnelle Innovation diagnostique dans les maladies rares, laboratoire de génétique chromosomique et moléculaire, Plateau Technique de Biologie, CHU Dijon Bourgogne, Dijon, France
| | - Diana Alcantara
- Human DNA Damage Response Disorders Group, University of Sussex, Genome Damage and Stability Centre, Brighton, United Kingdom
| | - Juliette Albuisson
- Service d’Oncogénétique, Centre Georges François Leclerc, Dijon, France
- Département de biologie et pathologie des tumeurs, Centre Georges François Leclerc, Dijon, France
| | | | - Céline Populaire
- Oncobiologie Génétique Bioinformatique, PCBio, CHU Besançon, Besançon, France
| | - Zohair Selmani
- Oncobiologie Génétique Bioinformatique, PCBio, CHU Besançon, Besançon, France
| | - Amandine Baurand
- Service d’Oncogénétique, Centre Georges François Leclerc, Dijon, France
- Centre de Génétique et Centre de Référence Maladies Rares Anomalies du Développement de l’Interrégion Est, Hôpital d’Enfants, CHU Dijon Bourgogne, Dijon, France
| | - Caroline Sawka
- Centre de Génétique et Centre de Référence Maladies Rares Anomalies du Développement de l’Interrégion Est, Hôpital d’Enfants, CHU Dijon Bourgogne, Dijon, France
| | - Geoffrey Bertolone
- Centre de Génétique et Centre de Référence Maladies Rares Anomalies du Développement de l’Interrégion Est, Hôpital d’Enfants, CHU Dijon Bourgogne, Dijon, France
| | - Patrick Callier
- Inserm UMR 1231 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
- Unité Fonctionnelle Innovation diagnostique dans les maladies rares, laboratoire de génétique chromosomique et moléculaire, Plateau Technique de Biologie, CHU Dijon Bourgogne, Dijon, France
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU TRANSLAD), CHU Dijon Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
| | - Yannis Duffourd
- Inserm UMR 1231 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU TRANSLAD), CHU Dijon Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
| | - Philippe Jonveaux
- Laboratoire de Génétique Médicale, INSERM U954, Hôpitaux de Brabois, Vandoeuvre les Nancy, France
| | - Yves-Jean Bignon
- Laboratoire d’Oncologie Moléculaire, Centre Jean Perrin, Clermont-Ferrand, France
| | | | - François Cornelis
- Université Bordeaux, IMB, UMR 5251, Talence, France
- Service d’imagerie diagnostique et interventionnelle de l’adulte, Hôpital Pellegrin, CHU de Bordeaux, France
| | | | | | - Jean-Baptiste Rivière
- Inserm UMR 1231 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
- Centre de Génétique et Centre de Référence Maladies Rares Anomalies du Développement de l’Interrégion Est, Hôpital d’Enfants, CHU Dijon Bourgogne, Dijon, France
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU TRANSLAD), CHU Dijon Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
| | - Paul Kuentz
- Inserm UMR 1231 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
- Oncobiologie Génétique Bioinformatique, PCBio, CHU Besançon, Besançon, France
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU TRANSLAD), CHU Dijon Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
| | - Christel Thauvin
- Inserm UMR 1231 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
- Centre de Génétique et Centre de Référence Maladies Rares Anomalies du Développement de l’Interrégion Est, Hôpital d’Enfants, CHU Dijon Bourgogne, Dijon, France
| | - Romain Boidot
- Département de biologie et pathologie des tumeurs, Centre Georges François Leclerc, Dijon, France
| | - François Ghiringhelli
- Département d’oncologie médicale, INSERM LNC U1231, Centre Georges François Leclerc, Dijon, France
| | - Marc O'Driscoll
- Human DNA Damage Response Disorders Group, University of Sussex, Genome Damage and Stability Centre, Brighton, United Kingdom
| | - Laurence Faivre
- Inserm UMR 1231 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
- Service d’Oncogénétique, Centre Georges François Leclerc, Dijon, France
- Centre de Génétique et Centre de Référence Maladies Rares Anomalies du Développement de l’Interrégion Est, Hôpital d’Enfants, CHU Dijon Bourgogne, Dijon, France
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU TRANSLAD), CHU Dijon Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
| | - Sophie Nambot
- Inserm UMR 1231 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
- Service d’Oncogénétique, Centre Georges François Leclerc, Dijon, France
- Centre de Génétique et Centre de Référence Maladies Rares Anomalies du Développement de l’Interrégion Est, Hôpital d’Enfants, CHU Dijon Bourgogne, Dijon, France
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU TRANSLAD), CHU Dijon Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
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Spatiotemporal 7q11.23 protein network analysis implicates the role of DNA repair pathway during human brain development. Sci Rep 2021; 11:8246. [PMID: 33859276 PMCID: PMC8050238 DOI: 10.1038/s41598-021-87632-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 03/25/2021] [Indexed: 01/10/2023] Open
Abstract
Recurrent deletions and duplications of chromosome 7q11.23 copy number variants (CNVs) are associated with several psychiatric disorders. Although phenotypic abnormalities have been observed in patients, causal genes responsible for CNV-associated diagnoses and traits are still poorly understood. Furthermore, the targeted human brain regions, developmental stages, protein networks, and signaling pathways, influenced by this CNV remain unclear. Previous works showed GTF2I involved in Williams-Beuren syndrome, but pathways affected by GTF2I are indistinct. We first constructed dynamic spatiotemporal networks of 7q11.23 genes by combining data from the brain developmental transcriptome with physical interactions of 7q11.23 proteins. Topological changes were observed in protein-protein interaction (PPI) networks throughout different stages of brain development. Early and late fetal periods of development in the cortex, striatum, hippocampus, and amygdale were observed as the vital periods and regions for 7q11.23 CNV proteins. CNV proteins and their partners are significantly enriched in DNA repair pathway. As a driver gene, GTF2I interacted with PRKDC and BRCA1 to involve in DNA repair pathway. The physical interaction between GTF2I with PRKDC was confirmed experimentally by the liquid chromatography-tandem mass spectrometry (LC-MS/MS). We identified that early and late fetal periods are crucial for 7q11.23 genes to affect brain development. Our results implicate that 7q11.23 CNV genes converge on the DNA repair pathway to contribute to the pathogenesis of psychiatric diseases.
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Schnabel F, Kornak U, Wollnik B. Premature aging disorders: A clinical and genetic compendium. Clin Genet 2020; 99:3-28. [PMID: 32860237 DOI: 10.1111/cge.13837] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 12/22/2022]
Abstract
Progeroid disorders make up a heterogeneous group of very rare hereditary diseases characterized by clinical signs that often mimic physiological aging in a premature manner. Apart from Hutchinson-Gilford progeria syndrome, one of the best-investigated progeroid disorders, a wide spectrum of other premature aging phenotypes exist, which differ significantly in their clinical presentation and molecular pathogenesis. Next-generation sequencing (NGS)-based approaches have made it feasible to determine the molecular diagnosis in the early stages of a disease. Nevertheless, a broad clinical knowledge on these disorders and their associated symptoms is still fundamental for a comprehensive patient management and for the interpretation of variants of unknown significance from NGS data sets. This review provides a detailed overview on characteristic clinical features and underlying molecular genetics of well-known as well as only recently identified premature aging disorders and also highlights novel findings towards future therapeutic options.
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Affiliation(s)
- Franziska Schnabel
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
| | - Uwe Kornak
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
| | - Bernd Wollnik
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable cells" (MBExC), University of Göttingen, Göttingen, Germany
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7
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Llinares-Benadero C, Borrell V. Deconstructing cortical folding: genetic, cellular and mechanical determinants. Nat Rev Neurosci 2019; 20:161-176. [DOI: 10.1038/s41583-018-0112-2] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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8
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Widger A, Mahadevaiah SK, Lange J, ElInati E, Zohren J, Hirota T, Pacheco S, Maldonado-Linares A, Stanzione M, Ojarikre O, Maciulyte V, de Rooij DG, Tóth A, Roig I, Keeney S, Turner JMA. ATR is a multifunctional regulator of male mouse meiosis. Nat Commun 2018; 9:2621. [PMID: 29976923 PMCID: PMC6033951 DOI: 10.1038/s41467-018-04850-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 05/24/2018] [Indexed: 11/25/2022] Open
Abstract
Meiotic cells undergo genetic exchange between homologs through programmed DNA double-strand break (DSB) formation, recombination and synapsis. In mice, the DNA damage-regulated phosphatidylinositol-3-kinase-like kinase (PIKK) ATM regulates all of these processes. However, the meiotic functions of the PIKK ATR have remained elusive, because germline-specific depletion of this kinase is challenging. Here we uncover roles for ATR in male mouse prophase I progression. ATR deletion causes chromosome axis fragmentation and germ cell elimination at mid pachynema. This elimination cannot be rescued by deletion of ATM and the third DNA damage-regulated PIKK, PRKDC, consistent with the existence of a PIKK-independent surveillance mechanism in the mammalian germline. ATR is required for synapsis, in a manner genetically dissociable from DSB formation. ATR also regulates loading of recombinases RAD51 and DMC1 to DSBs and recombination focus dynamics on synapsed and asynapsed chromosomes. Our studies reveal ATR as a critical regulator of mouse meiosis.
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Affiliation(s)
- Alexander Widger
- Sex Chromosome Biology Lab, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Shantha K Mahadevaiah
- Sex Chromosome Biology Lab, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Julian Lange
- Molecular Biology Program, Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Elias ElInati
- Sex Chromosome Biology Lab, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Jasmin Zohren
- Sex Chromosome Biology Lab, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Takayuki Hirota
- Sex Chromosome Biology Lab, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Sarai Pacheco
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain
- Department of Cell Biology, Physiology and Immunology, Cytology and Histology Unit, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain
| | - Andros Maldonado-Linares
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain
- Department of Cell Biology, Physiology and Immunology, Cytology and Histology Unit, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain
| | - Marcello Stanzione
- Institute of Physiological Chemistry, Faculty of Medicine at the TU Dresden, Fetscherstraße 74, 01307, Dresden, Germany
| | - Obah Ojarikre
- Sex Chromosome Biology Lab, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Valdone Maciulyte
- Sex Chromosome Biology Lab, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Dirk G de Rooij
- Center for Reproductive Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, 1105 AZ, The Netherlands
| | - Attila Tóth
- Institute of Physiological Chemistry, Faculty of Medicine at the TU Dresden, Fetscherstraße 74, 01307, Dresden, Germany
| | - Ignasi Roig
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain
- Department of Cell Biology, Physiology and Immunology, Cytology and Histology Unit, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain
| | - Scott Keeney
- Molecular Biology Program, Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - James M A Turner
- Sex Chromosome Biology Lab, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
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9
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Duerinckx S, Verhelst H, Perazzolo C, David P, Desmyter L, Pirson I, Abramowicz M. Severe congenital microcephaly with AP4M1 mutation, a case report. BMC MEDICAL GENETICS 2017; 18:48. [PMID: 28464862 PMCID: PMC5414176 DOI: 10.1186/s12881-017-0412-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 04/20/2017] [Indexed: 12/30/2022]
Abstract
Background Autosomal recessive defects of either the B1, E1, M1 or S1 subunit of the Adaptor Protein complex-4 (AP4) are characterized by developmental delay, severe intellectual disability, spasticity, and occasionally mild to moderate microcephaly of essentially postnatal onset. Case presentation We report on a patient with severe microcephaly of prenatal onset, and progressive spasticity, developmental delay, and severe intellectual deficiency. Exome sequencing showed a homozygous mutation in AP4M1, causing the replacement of an arginine by a stop codon at position 338 of the protein (p.Arg338X). The premature stop codon truncates the Mu homology domain of AP4M1, with predicted loss of function. Exome analysis also showed heterozygous variants in three genes, ATR, MCPH1 and BLM, which are known causes of autosomal recessive primary microcephaly. Conclusions Our findings expand the AP4M1 phenotype to severe microcephaly of prenatal onset, and more generally suggest that the AP4 defect might share mechanisms of prenatal neuronal depletion with other genetic defects of brain development causing congenital, primary microcephaly. Electronic supplementary material The online version of this article (doi:10.1186/s12881-017-0412-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Helene Verhelst
- Department of Paediatric Neurology, Ghent University Hospital, Ghent, Belgium
| | | | - Philippe David
- Department of Medical Imaging and Radiology, Hôpital Erasme - Université Libre de Bruxelles, Brussels, Belgium
| | - Laurence Desmyter
- Department of Medical Genetics, Hôpital Erasme - Université Libre de Bruxelles, Brussels, Belgium
| | | | - Marc Abramowicz
- IRIBHM, Université Libre de Bruxelles, Brussels, Belgium. .,Department of Medical Genetics, Hôpital Erasme - Université Libre de Bruxelles, Brussels, Belgium.
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10
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Guenat D, Merla G, Deconinck E, Borg C, Rohrlich PS. DNA damage response defect in Williams-Beuren syndrome. Int J Mol Med 2017; 39:622-628. [PMID: 28098859 PMCID: PMC5360356 DOI: 10.3892/ijmm.2017.2861] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/29/2016] [Indexed: 11/19/2022] Open
Abstract
Williams-Beuren syndrome (WBS, no. OMIM 194050) is a rare multisystem genetic disorder caused by a microdeletion on chromosome 7q11.23 and characterized by cardiovascular malformations, mental retardation, and a specific facial dysmorphism. Recently, we reported that a series of non-Hodgkin's lymphoma occurs in children with WBS and thus hypothesized that a predisposition to cancer may be associated with this genetic disorder. The aim of the present study was to ascertain the role played by three genes hemizygously deleted in WBS (RFC2, GTF2I and BAZ1B) in DNA damage response pathways. Cell proliferation, cell cycle analysis, γ-H2A.X induction, and expression of DNA damage response proteins were investigated upon exposure to genotoxic treatments in WBS patient-derived primary fibroblasts and in the 293T cell line treated with specific siRNAs targeting RFC2, GTF2I and BAZ1B. An impaired hydroxyurea-induced phosphorylation of CHK1 was observed in the WBS cells. However, this defective DNA damage response was not associated with an increased sensitivity to genotoxic agents. In addition, depletion of RFC2, GTF2I and BAZ1B using specific siRNAs did not have a significant impact on the DNA damage response in 293T cells. Our results highlight that the ATR-dependent DNA damage response is impaired in WBS patient cells but is also dispensable for viability when these cells undergo a genotoxic stress. The mechanism by which the ATR pathway is impaired in WBS warrants elucidation through further investigation.
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Affiliation(s)
- David Guenat
- Laboratory of Cellular and Molecular Biology, University Hospital of Besançon, F-25000 Besançon, France
| | - Giuseppe Merla
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia I‑71013, Italy
| | - Eric Deconinck
- Inserm UMR1098/EFS‑BFC/University of Franche‑Comte, LabEx LipSTIC, F-25000 Besançon, France
| | - Christophe Borg
- Inserm UMR1098/EFS‑BFC/University of Franche‑Comte, LabEx LipSTIC, F-25000 Besançon, France
| | - Pierre-Simon Rohrlich
- Inserm UMR1098/EFS‑BFC/University of Franche‑Comte, LabEx LipSTIC, F-25000 Besançon, France
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11
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O'Driscoll M. The pathological consequences of impaired genome integrity in humans; disorders of the DNA replication machinery. J Pathol 2017; 241:192-207. [PMID: 27757957 DOI: 10.1002/path.4828] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/12/2016] [Accepted: 10/13/2016] [Indexed: 12/13/2022]
Abstract
Accurate and efficient replication of the human genome occurs in the context of an array of constitutional barriers, including regional topological constraints imposed by chromatin architecture and processes such as transcription, catenation of the helical polymer and spontaneously generated DNA lesions, including base modifications and strand breaks. DNA replication is fundamentally important for tissue development and homeostasis; differentiation programmes are intimately linked with stem cell division. Unsurprisingly, impairments of the DNA replication machinery can have catastrophic consequences for genome stability and cell division. Functional impacts on DNA replication and genome stability have long been known to play roles in malignant transformation through a variety of complex mechanisms, and significant further insights have been gained from studying model organisms in this context. Congenital hypomorphic defects in components of the DNA replication machinery have been and continue to be identified in humans. These disorders present with a wide range of clinical features. Indeed, in some instances, different mutations in the same gene underlie different clinical presentations. Understanding the origin and molecular basis of these features opens a window onto the range of developmental impacts of suboptimal DNA replication and genome instability in humans. Here, I will briefly overview the basic steps involved in DNA replication and the key concepts that have emerged from this area of research, before switching emphasis to the pathological consequences of defects within the DNA replication network; the human disorders. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Mark O'Driscoll
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
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12
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Ma CJ, Gibb B, Kwon Y, Sung P, Greene EC. Protein dynamics of human RPA and RAD51 on ssDNA during assembly and disassembly of the RAD51 filament. Nucleic Acids Res 2016; 45:749-761. [PMID: 27903895 PMCID: PMC5314761 DOI: 10.1093/nar/gkw1125] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 10/21/2016] [Accepted: 10/27/2016] [Indexed: 12/31/2022] Open
Abstract
Homologous recombination (HR) is a crucial pathway for double-stranded DNA break (DSB) repair. During the early stages of HR, the newly generated DSB ends are processed to yield long single-stranded DNA (ssDNA) overhangs, which are quickly bound by replication protein A (RPA). RPA is then replaced by the DNA recombinase Rad51, which forms extended helical filaments on the ssDNA. The resulting nucleoprotein filament, known as the presynaptic complex, is responsible for pairing the ssDNA with homologous double-stranded DNA (dsDNA), which serves as the template to guide DSB repair. Here, we use single-molecule imaging to visualize the interplay between human RPA (hRPA) and human RAD51 during presynaptic complex assembly and disassembly. We demonstrate that ssDNA-bound hRPA can undergo facilitated exchange, enabling hRPA to undergo rapid exchange between free and ssDNA-bound states only when free hRPA is present in solution. Our results also indicate that the presence of free hRPA inhibits RAD51 filament nucleation, but has a lesser impact upon filament elongation. This finding suggests that hRPA exerts important regulatory influence over RAD51 and may in turn affect the properties of the assembled RAD51 filament. These experiments provide an important basis for further investigations into the regulation of human presynaptic complex assembly.
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Affiliation(s)
- Chu Jian Ma
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Bryan Gibb
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - YoungHo Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
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13
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Krasikova YS, Rechkunova NI, Lavrik OI. Replication protein A as a major eukaryotic single-stranded DNA-binding protein and its role in DNA repair. Mol Biol 2016. [DOI: 10.1134/s0026893316030080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Taniguchi JB, Kondo K, Fujita K, Chen X, Homma H, Sudo T, Mao Y, Watase K, Tanaka T, Tagawa K, Tamura T, Muramatsu SI, Okazawa H. RpA1 ameliorates symptoms of mutant ataxin-1 knock-in mice and enhances DNA damage repair. Hum Mol Genet 2016; 25:4432-4447. [DOI: 10.1093/hmg/ddw272] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/08/2016] [Accepted: 08/05/2016] [Indexed: 01/05/2023] Open
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15
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The Response to Oxidative DNA Damage in Neurons: Mechanisms and Disease. Neural Plast 2016; 2016:3619274. [PMID: 26942017 PMCID: PMC4752990 DOI: 10.1155/2016/3619274] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 12/24/2015] [Indexed: 11/26/2022] Open
Abstract
There is a growing body of evidence indicating that the mechanisms that control genome stability are of key importance in the development and function of the nervous system. The major threat for neurons is oxidative DNA damage, which is repaired by the base excision repair (BER) pathway. Functional mutations of enzymes that are involved in the processing of single-strand breaks (SSB) that are generated during BER have been causally associated with syndromes that present important neurological alterations and cognitive decline. In this review, the plasticity of BER during neurogenesis and the importance of an efficient BER for correct brain function will be specifically addressed paying particular attention to the brain region and neuron-selectivity in SSB repair-associated neurological syndromes and age-related neurodegenerative diseases.
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16
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Chen R, Wold MS. Replication protein A: single-stranded DNA's first responder: dynamic DNA-interactions allow replication protein A to direct single-strand DNA intermediates into different pathways for synthesis or repair. Bioessays 2014; 36:1156-61. [PMID: 25171654 DOI: 10.1002/bies.201400107] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Replication protein A (RPA), the major single-stranded DNA-binding protein in eukaryotic cells, is required for processing of single-stranded DNA (ssDNA) intermediates found in replication, repair, and recombination. Recent studies have shown that RPA binding to ssDNA is highly dynamic and that more than high-affinity binding is needed for function. Analysis of DNA binding mutants identified forms of RPA with reduced affinity for ssDNA that are fully active, and other mutants with higher affinity that are inactive. Single molecule studies showed that while RPA binds ssDNA with high affinity, the RPA complex can rapidly diffuse along ssDNA and be displaced by other proteins that act on ssDNA. Finally, dynamic DNA binding allows RPA to prevent error-prone repair of double-stranded breaks and promote error-free repair. Together, these findings suggest a new paradigm where RPA acts as a first responder at sites with ssDNA, thereby actively coordinating DNA repair and DNA synthesis.
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Affiliation(s)
- Ran Chen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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17
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Khan AO, Nagl S, Bergmann C, Bolz HJ. Limited ocular motility in a child with 3q23 microdeletion ("blepharophimosis syndrome plus"). J Pediatr Ophthalmol Strabismus 2014; 51 Online:e51-4. [PMID: 25032695 DOI: 10.3928/01913913-20140709-04] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 06/12/2014] [Indexed: 11/20/2022]
Abstract
Blepharophimosis syndrome is a recognizable ocular phenotype (blepharophimosis, telecanthus, ptosis, and epicanthus inversus) caused by heterozygous (dominant) intragenic mutation in FOXL2 (chromosome 3q23), which can also cause premature ovarian failure. A deletion that involves not only FOXL2 but also adjacent genes can result in additional clinical features ("blepharophimosis syndrome plus"). Studies of such patients are useful because observed additional clinical features suggest potential functions of genes adjacent to FOXL2. The authors describe a boy with blepharophimosis syndrome plus from a de novo heterozygous 3q22.3-q24 11.2 Mb microdeletion. Among his additional clinical features was bilateral limitation of abduction and supraduction, which suggests that the deleted area includes a gene responsible for ocular motility.
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18
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Dean SJ, Holden KR, Dwivedi A, Dupont BR, Lyons MJ. Acquired microcephaly in blepharophimosis-ptosis-epicanthus inversus syndrome because of an interstitial 3q22.3q23 deletion. Pediatr Neurol 2014; 50:636-9. [PMID: 24725350 DOI: 10.1016/j.pediatrneurol.2014.01.055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 01/10/2014] [Accepted: 01/18/2014] [Indexed: 11/15/2022]
Abstract
BACKGROUND Blepharophimosis-ptosis-epicanthus inversus syndrome is an autosomal dominant condition because of mutations or deletions of the FOXL2 gene. Microcephaly is not associated with FOXL2 mutations but has been reported in individuals with chromosome 3q deletions, which include the FOXL2 gene and other contiguous genes. The ATR gene has been reported as a candidate gene for microcephaly in individuals with contiguous deletion of chromosome 3q involving the FOXL2 gene. PATIENT We describe a girl with blepharophimosis-ptosis-epicanthus inversus syndrome along with acquired microcephaly and intellectual disability. RESULTS Our patient had a deletion of chromosome 3q22.2q23, which does not include the ATR gene but does include the PIK3CB gene as a candidate gene for microcephaly. CONCLUSION We propose that the PIK3CB gene included in our patient's chromosome 3q deletion may be the gene responsible for microcephaly and other patients with blepharophimosis-ptosis-epicanthus inversus syndrome because of a chromosome 3q deletion.
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Affiliation(s)
- Sarah J Dean
- College of Medicine, Medical University of South Carolina, Charleston, South Carolina.
| | - Kenton R Holden
- Neurosciences (Neurology) and Pediatrics, Medical University of South Carolina, Charleston, South Carolina; Greenwood Genetic Center, Greenwood, South Carolina
| | - Alka Dwivedi
- Greenwood Genetic Center, Greenwood, South Carolina
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19
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McKinnon PJ. Maintaining genome stability in the nervous system. Nat Neurosci 2013; 16:1523-9. [PMID: 24165679 PMCID: PMC4112580 DOI: 10.1038/nn.3537] [Citation(s) in RCA: 165] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 09/11/2013] [Indexed: 01/09/2023]
Abstract
Active maintenance of genome stability is a prerequisite for the development and function of the nervous system. The high replication index during neurogenesis and the long life of mature neurons highlight the need for efficient cellular programs to safeguard genetic fidelity. Multiple DNA damage response pathways ensure that replication stress and other types of DNA lesions, such as oxidative damage, do not affect neural homeostasis. Numerous human neurologic syndromes result from defective DNA damage signaling and compromised genome integrity. These syndromes can involve different neuropathology, which highlights the diverse maintenance roles that are required for genome stability in the nervous system. Understanding how DNA damage signaling pathways promote neural development and preserve homeostasis is essential for understanding fundamental brain function.
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Affiliation(s)
- Peter J. McKinnon
- Department of Genetics, St Jude Children’s Research Hospital, Memphis TN, USA
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20
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Shiloh Y, Ziv Y. The ATM protein kinase: regulating the cellular response to genotoxic stress, and more. Nat Rev Mol Cell Biol 2013; 14:197-210. [DOI: 10.1038/nrm3546] [Citation(s) in RCA: 1170] [Impact Index Per Article: 106.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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21
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Brett MS, Ng ISL, Lim ECP, Yong MH, Li Z, Lai A, Tan EC. De novo 3q22.1 q24 deletion associated with multiple congenital anomalies, growth retardation and intellectual disability. Gene 2013; 517:82-8. [PMID: 23313878 DOI: 10.1016/j.gene.2012.12.082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 11/15/2012] [Accepted: 12/19/2012] [Indexed: 10/27/2022]
Abstract
We describe a boy with a de novo deletion of 15.67 Mb spanning 3q22.1q24. He has bilateral micropthalmia, ptosis, cleft palate, global developmental delay and brain, skeletal and cardiac abnormalities. In addition, he has bilateral inguinal hernia and his right kidney is absent. We compare his phenotype with seven other patients with overlapping and molecularly defined interstitial 3q deletions. This patient has some phenotypic features that are not shared by the other patients. More cases with smaller deletions defined by high resolution aCGH will enable better genotype-phenotype correlations and prioritizing of candidate genes for the identification of pathways and disease mechanisms.
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Affiliation(s)
- Maggie S Brett
- KK Research Centre, KK Women's & Children's Hospital, Singapore
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22
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Mokrani-Benhelli H, Gaillard L, Biasutto P, Le Guen T, Touzot F, Vasquez N, Komatsu J, Conseiller E, Pïcard C, Gluckman E, Francannet C, Fischer A, Durandy A, Soulier J, de Villartay JP, Cavazzana-Calvo M, Revy P. Primary microcephaly, impaired DNA replication, and genomic instability caused by compound heterozygous ATR mutations. Hum Mutat 2012; 34:374-84. [PMID: 23111928 DOI: 10.1002/humu.22245] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 10/22/2012] [Indexed: 11/10/2022]
Abstract
Ataxia telangiectasia-mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR) kinases are two key regulators of DNA-damage responses (DDR) that are mainly activated in response to DNA double-strand breaks and single-stranded DNA damages, respectively. Seckel syndrome, a rare genetic disorder characterized by a microcephaly and a markedly reduced body size, has been associated with defective ATR-dependent DNA damage signaling. However, the only human genetic ATR defect reported so far is a hypomorphic splicing mutation identified in five related individuals with Seckel syndrome. Here, we report the first case of primary microcephaly with compound heterozygous mutations in ATR: a 540 kb genomic deletion on one allele and a missense mutation leading to splice dysregulation on the other, which ultimately lead to a sharp decrease in ATR expression. DNA combing technology revealed a profound spontaneous alteration of several DNA replication parameters in patient's cells and FISH analyses highlighted the genomic instability caused by ATR deficiency. Collectively, our results emphasize the crucial role for ATR in the control of DNA replication, and reinforce the complementary and nonredundant contributions of ATM and ATR in human cells to face DNA damages and warrant genome integrity.
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23
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Spengler S, Begemann M, Ortiz Brüchle N, Baudis M, Denecke B, Kroisel PM, Oehl-Jaschkowitz B, Schulze B, Raabe-Meyer G, Spaich C, Blümel P, Jauch A, Moog U, Zerres K, Eggermann T. Molecular karyotyping as a relevant diagnostic tool in children with growth retardation with Silver-Russell features. J Pediatr 2012; 161:933-42. [PMID: 22683032 DOI: 10.1016/j.jpeds.2012.04.045] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 03/22/2012] [Accepted: 04/23/2012] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To determine the contribution of submicroscopic chromosomal imbalances to the etiology of Silver-Russell syndrome (SRS) and SRS-like phenotypes. STUDY DESIGN We performed molecular karyotyping in 41 patients with SRS or SRS-like features without known chromosome 7 and 11 defects using the Affymetrix SNP Array 6.0 system (Affymetrix, High Wycombe, United Kingdom). RESULTS In 8 patients, pathogenic copy number variations with sizes ranging from 672 kb to 9.158 Mb were identified. The deletions in 1q21, 15q26, 17p13, and 22q11 were associated with known microdeletion syndromes with overlapping features with SRS. The duplications in 22q13 and Xq25q27 represent unique novel copy number variations but have an obvious influence on the phenotype. In 5 additional patients, the pathogenetic relevance of the detected variants remained unclear. CONCLUSION Pathogenic submicroscopic imbalances were detectable in a significant proportion of patients with short stature and features reminiscent of SRS. Therefore, molecular karyotyping should be implemented in routine diagnostics for growth-retarded patients with even slight dysmorphisms suggestive for SRS.
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Tomicic MT, Kaina B. Topoisomerase degradation, DSB repair, p53 and IAPs in cancer cell resistance to camptothecin-like topoisomerase I inhibitors. Biochim Biophys Acta Rev Cancer 2012; 1835:11-27. [PMID: 23006513 DOI: 10.1016/j.bbcan.2012.09.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 09/13/2012] [Accepted: 09/15/2012] [Indexed: 12/11/2022]
Abstract
Topoisomerase I (TOP1) inhibitors applied in cancer therapy such as topotecan and irinotecan are derivatives of the natural alkaloid camptothecin (CPT). The mechanism of CPT poisoning of TOP1 rests on inhibition of the re-ligation function of the enzyme resulting in the stabilization of the TOP1-cleavable complex. In the presence of CPTs this enzyme-DNA complex impairs transcription and DNA replication, resulting in fork stalling and the formation of DNA double-strand breaks (DSB) in proliferating cells. As with most chemotherapeutics, intrinsic and acquired drug resistance represents a hurdle that limits the success of CPT therapy. Preclinical data indicate that resistance to CPT-based drugs might be caused by factors such as (a) poor drug accumulation in the tumor, (b) high rate of drug efflux, (c) mutations in TOP1 leading to failure in CPT docking, or (d) altered signaling triggered by the drug-TOP1-DNA complex, (e) expression of DNA repair proteins, and (f) failure to activate cell death pathways. This review will focus on the issues (d-f). We discuss degradation of TOP1 as part of the repair pathway in the processing of TOP1 associated DNA damage, give a summary of proteins involved in repair of CPT-induced replication mediated DSB, and highlight the role of p53 and inhibitors of apoptosis proteins (IAPs), particularly XIAP and survivin, in cancer cell resistance to CPT-like chemotherapeutics.
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Affiliation(s)
- Maja T Tomicic
- Department of Toxicology, University Medical Center Mainz, Germany.
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25
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Abstract
Prevention and repair of DNA damage is essential for maintenance of genomic stability and cell survival. DNA replication during S-phase can be a source of DNA damage if endogenous or exogenous stresses impair the progression of replication forks. It has become increasingly clear that DNA-damage-response pathways do not only respond to the presence of damaged DNA, but also modulate DNA replication dynamics to prevent DNA damage formation during S-phase. Such observations may help explain the developmental defects or cancer predisposition caused by mutations in DNA-damage-response genes. The present review focuses on molecular mechanisms by which DNA-damage-response pathways control and promote replication dynamics in vertebrate cells. In particular, DNA damage pathways contribute to proper replication by regulating replication initiation, stabilizing transiently stalled forks, promoting replication restart and facilitating fork movement on difficult-to-replicate templates. If replication fork progression fails to be rescued, this may lead to DNA damage and genomic instability via nuclease processing of aberrant fork structures or incomplete sister chromatid separation during mitosis.
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Savina NV, Smal MP, Kuzhir TD, Egorova TM, Khurs OM, Polityko AD, Goncharova RI. Biomarkers for genome instability in some genetic disorders: a pilot study. Biomarkers 2012; 17:201-8. [DOI: 10.3109/1354750x.2011.651157] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Fitzgerald B, O'Driscoll M, Chong K, Keating S, Shannon P. Neuropathology of fetal stage Seckel syndrome: a case report providing a morphological correlate for the emerging molecular mechanisms. Brain Dev 2012; 34:238-43. [PMID: 21669506 DOI: 10.1016/j.braindev.2011.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 05/16/2011] [Accepted: 05/17/2011] [Indexed: 11/25/2022]
Abstract
Seckel syndrome is a rare autosomal recessive disorder characterized by intrauterine growth retardation, dwarfism, microcephaly and mental retardation. Pathological descriptions of fetal stage Seckel syndrome are rare and pre-date the evolving understanding of the genetic and molecular mechanisms involved. The autopsy findings in a case of fetal Seckel syndrome at 30 weeks gestation are presented, with detailed description of the neuropathological findings. Severe neurological abnormalities in a male fetus were observed that included microencephaly, cortical neuronal migration disorder, white matter tract hypoplasia/aplasia, premature depletion of the germinal matrix with cystic transformation and patchy absence of the external granular cell layer of the cerebellum. The striking neuropathological finding in this case was evidence of failure of the developing brain's germinal elements, providing rare morphological insight into the abnormal development of the Seckel syndrome fetal brain. The selective failure of this proliferating cell population correlates with the emerging molecular evidence that Seckel syndrome is caused by defects in ATR-dependent DNA damage signaling with resultant premature death of proliferating cells.
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Affiliation(s)
- Brendan Fitzgerald
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Canada
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Abstract
Nijmegen breakage syndrome (NBS) is a rare autosomal recessive syndrome of chromosomal instability mainly characterized by microcephaly at birth, combined immunodeficiency and predisposition to malignancies. Due to a founder mutation in the underlying NBN gene (c.657_661del5) the disease is encountered most frequently among Slavic populations. The principal clinical manifestations of the syndrome are: microcephaly, present at birth and progressive with age, dysmorphic facial features, mild growth retardation, mild-to-moderate intellectual disability, and, in females, hypergonadotropic hypogonadism. Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome. The NBN gene codes for nibrin which, as part of a DNA repair complex, plays a critical nuclear role wherever double-stranded DNA ends occur, either physiologically or as a result of mutagenic exposure. Laboratory findings include: (1) spontaneous chromosomal breakage in peripheral T lymphocytes with rearrangements preferentially involving chromosomes 7 and 14, (2) sensitivity to ionizing radiation or radiomimetics as demonstrated in vitro by cytogenetic methods or by colony survival assay, (3) radioresistant DNA synthesis, (4) biallelic hypomorphic mutations in the NBN gene, and (5) absence of full-length nibrin protein. Microcephaly and immunodeficiency are common to DNA ligase IV deficiency (LIG4 syndrome) and severe combined immunodeficiency with microcephaly, growth retardation, and sensitivity to ionizing radiation due to NHEJ1 deficiency (NHEJ1 syndrome). In fact, NBS was most commonly confused with Fanconi anaemia and LIG4 syndrome. Genetic counselling should inform parents of an affected child of the 25% risk for further children to be affected. Prenatal molecular genetic diagnosis is possible if disease-causing mutations in both alleles of the NBN gene are known. No specific therapy is available for NBS, however, hematopoietic stem cell transplantation may be one option for some patients. Prognosis is generally poor due to the extremely high rate of malignancies. Zespół Nijmegen (Nijmegen breakage syndrome; NBS) jest rzadkim schorzeniem z wrodzoną niestabilnością chromosomową dziedziczącym się w sposób autosomalny recesywny, charakteryzującym się przede wszystkim wrodzonym małogłowiem, złożonymi niedoborami odporności i predyspozycją do rozwoju nowotworów. Choroba występuje najczęściej w populacjach słowiańskich, w których uwarunkowana jest mutacją założycielską w genie NBN (c.657_661del5). Do najważniejszych objawów zespołu zalicza się: małogłowie obecne od urodzenia i postępujące z wiekiem, charakterystyczne cechy dysmorfii twarzy, opóźnienie wzrastania, niepełnosprawność intelektualną w stopniu lekkim do umiarkowanego oraz hipogonadyzm hipogonadotropowy u dziewcząt. Na obraz choroby składają się także: niedobór odporności komórkowej i humoralnej, który jest przyczyną nawracających infekcji, znaczna predyspozycja do rozwoju nowotworów złośliwych (zwłaszcza układu chłonnego), a także zwiększona wrażliwość na promieniowanie jonizujące. Wyniki badań laboratoryjnych wykazują: (1) spontaniczną łamliwość chromosomów w limfocytach T krwi obwodowej, z preferencją do rearanżacji chromosomów 7 i 14, (2) nadwrażliwość na promieniowanie jonizujące lub radiomimetyki, co można wykazać metodami in vitro, (3) radiooporność syntezy DNA, (4) hipomorficzne mutacje na obu allelach genu NBN, oraz (5) brak w komórkach pełnej cząsteczki białka, nibryny. Małogłowie i niedobór odporności występują także w zespole niedoboru ligazy IV (LIG4) oraz w zespole niedoboru NHEJ1. Rodzice powinni otrzymać poradę genetyczną ze względu na wysokie ryzyko (25%) powtórzenia się choroby u kolejnego potomstwa. Możliwe jest zaproponowanie molekularnej diagnostyki prenatalnej jeżeli znane są obie mutacje będące przyczyną choroby. Nie ma możliwości zaproponowania specyficznej terapii, ale przeszczep szpiku może być alternatywą dla niektórych pacjentów. Generalnie prognoza nie jest pomyślna z uwagi na wysokie ryzyko rozwoju nowotworu.
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Abstract
Replication protein A (RPA), the major eukaryotic single-strand DNA (ssDNA)-binding protein, is essential for replication, repair, recombination, and checkpoint activation. Defects in RPA-associated cellular activities lead to genomic instability, a major factor in the pathogenesis of cancer and other diseases. ssDNA binding activity is primarily mediated by two domains in the 70-kDa subunit of the RPA complex. These ssDNA interactions are mediated by a combination of polar residues and four conserved aromatic residues. Mutation of the aromatic residues causes a modest decrease in binding to long (30-nucleotide) ssDNA fragments but results in checkpoint activation and cell cycle arrest in cells. We have used a combination of biochemical analysis and knockdown replacement studies in cells to determine the contribution of these aromatic residues to RPA function. Cells containing the aromatic residue mutants were able to progress normally through S-phase but were defective in DNA repair. Biochemical characterization revealed that mutation of the aromatic residues severely decreased binding to short ssDNA fragments less than 20 nucleotides long. These data indicate that altered binding of RPA to short ssDNA intermediates causes a defect in DNA repair but not in DNA replication. These studies show that cells require different RPA functions in DNA replication and DNA repair.
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Affiliation(s)
- Cathy S Hass
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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Outwin E, Carpenter G, Bi W, Withers MA, Lupski JR, O'Driscoll M. Increased RPA1 gene dosage affects genomic stability potentially contributing to 17p13.3 duplication syndrome. PLoS Genet 2011; 7:e1002247. [PMID: 21901111 PMCID: PMC3161930 DOI: 10.1371/journal.pgen.1002247] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 07/03/2011] [Indexed: 11/18/2022] Open
Abstract
A novel microduplication syndrome involving various-sized contiguous duplications in 17p13.3 has recently been described, suggesting that increased copy number of genes in 17p13.3, particularly PAFAH1B1, is associated with clinical features including facial dysmorphism, developmental delay, and autism spectrum disorder. We have previously shown that patient-derived cell lines from individuals with haploinsufficiency of RPA1, a gene within 17p13.3, exhibit an impaired ATR-dependent DNA damage response (DDR). Here, we show that cell lines from patients with duplications specifically incorporating RPA1 exhibit a different although characteristic spectrum of DDR defects including abnormal S phase distribution, attenuated DNA double strand break (DSB)-induced RAD51 chromatin retention, elevated genomic instability, and increased sensitivity to DNA damaging agents. Using controlled conditional over-expression of RPA1 in a human model cell system, we also see attenuated DSB-induced RAD51 chromatin retention. Furthermore, we find that transient over-expression of RPA1 can impact on homologous recombination (HR) pathways following DSB formation, favouring engagement in aberrant forms of recombination and repair. Our data identifies unanticipated defects in the DDR associated with duplications in 17p13.3 in humans involving modest RPA1 over-expression.
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Affiliation(s)
- Emily Outwin
- Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Gillian Carpenter
- Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Weimin Bi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Medical Genetics Laboratories, Baylor College of Medicine, Houston, Texas, United States of America
| | - Marjorie A. Withers
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Medical Genetics Laboratories, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mark O'Driscoll
- Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
- * E-mail:
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Harvard C, Strong E, Mercier E, Colnaghi R, Alcantara D, Chow E, Martell S, Tyson C, Hrynchak M, McGillivray B, Hamilton S, Marles S, Mhanni A, Dawson AJ, Pavlidis P, Qiao Y, Holden JJ, Lewis SME, O'Driscoll M, Rajcan-Separovic E. Understanding the impact of 1q21.1 copy number variant. Orphanet J Rare Dis 2011; 6:54. [PMID: 21824431 PMCID: PMC3180300 DOI: 10.1186/1750-1172-6-54] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Accepted: 08/08/2011] [Indexed: 01/10/2023] Open
Abstract
Background 1q21.1 Copy Number Variant (CNV) is associated with a highly variable phenotype ranging from congenital anomalies, learning deficits/intellectual disability (ID), to a normal phenotype. Hence, the clinical significance of this CNV can be difficult to evaluate. Here we described the consequences of the 1q21.1 CNV on genome-wide gene expression and function of selected candidate genes within 1q21.1 using cell lines from clinically well described subjects. Methods and Results Eight subjects from 3 families were included in the study: six with a 1q21.1 deletion and two with a 1q21.1 duplication. High resolution Affymetrix 2.7M array was used to refine the 1q21.1 CNV breakpoints and exclude the presence of secondary CNVs of pathogenic relevance. Whole genome expression profiling, studied in lymphoblast cell lines (LBCs) from 5 subjects, showed enrichment of genes from 1q21.1 in the top 100 genes ranked based on correlation of expression with 1q21.1 copy number. The function of two top genes from 1q21.1, CHD1L/ALC1 and PRKAB2, was studied in detail in LBCs from a deletion and a duplication carrier. CHD1L/ALC1 is an enzyme with a role in chromatin modification and DNA damage response while PRKAB2 is a member of the AMP kinase complex, which senses and maintains systemic and cellular energy balance. The protein levels for CHD1L/ALC1 and PRKAB2 were changed in concordance with their copy number in both LBCs. A defect in chromatin remodeling was documented based on impaired decatenation (chromatid untangling) checkpoint (DCC) in both LBCs. This defect, reproduced by CHD1L/ALC1 siRNA, identifies a new role of CHD1L/ALC1 in DCC. Both LBCs also showed elevated levels of micronuclei following treatment with a Topoisomerase II inhibitor suggesting increased DNA breaks. AMP kinase function, specifically in the deletion containing LBCs, was attenuated. Conclusion Our studies are unique as they show for the first time that the 1q21.1 CNV not only causes changes in the expression of its key integral genes, associated with changes at the protein level, but also results in changes in their known function, in the case of AMPK, and newly identified function such as DCC activation in the case of CHD1L/ALC1. Our results support the use of patient lymphoblasts for dissecting the functional sequelae of genes integral to CNVs in carrier cell lines, ultimately enhancing understanding of biological processes which may contribute to the clinical phenotype.
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Affiliation(s)
- Chansonette Harvard
- Child and Family Research Institute, Molecular Cytogenetics and Array Laboratory, 950 West 28th Avenue, Vancouver, BC, Canada
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Colnaghi R, Carpenter G, Volker M, O'Driscoll M. The consequences of structural genomic alterations in humans: genomic disorders, genomic instability and cancer. Semin Cell Dev Biol 2011; 22:875-85. [PMID: 21802523 DOI: 10.1016/j.semcdb.2011.07.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 07/11/2011] [Accepted: 07/14/2011] [Indexed: 12/20/2022]
Abstract
Over the last decade or so, sophisticated technological advances in array-based genomics have firmly established the contribution of structural alterations in the human genome to a variety of complex developmental disorders, and also to diseases such as cancer. In fact, multiple 'novel' disorders have been identified as a direct consequence of these advances. Our understanding of the molecular events leading to the generation of these structural alterations is also expanding. Many of the models proposed to explain these complex rearrangements involve DNA breakage and the coordinated action of DNA replication, repair and recombination machinery. Here, and within the context of Genomic Disorders, we will briefly overview the principal models currently invoked to explain these chromosomal rearrangements, including Non-Allelic Homologous Recombination (NAHR), Fork Stalling Template Switching (FoSTeS), Microhomology Mediated Break-Induced Repair (MMBIR) and Breakage-fusion-bridge cycle (BFB). We will also discuss an unanticipated consequence of certain copy number variations (CNVs) whereby the CNVs potentially compromise fundamental processes controlling genomic stability including DNA replication and the DNA damage response. We will illustrate these using specific examples including Genomic Disorders (DiGeorge/Veleocardiofacial syndrome, HSA21 segmental aneuploidy and rec (3) syndrome) and cell-based model systems. Finally, we will review some of the recent exciting developments surrounding specific CNVs and their contribution to cancer development as well as the latest model for cancer genome rearrangement; 'chromothripsis'.
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Affiliation(s)
- Rita Colnaghi
- Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
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O'Driscoll M. Haploinsufficiency of DNA Damage Response Genes and their Potential Influence in Human Genomic Disorders. Curr Genomics 2011; 9:137-46. [PMID: 19440510 PMCID: PMC2679649 DOI: 10.2174/138920208784340795] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 03/31/2008] [Accepted: 03/31/2008] [Indexed: 11/22/2022] Open
Abstract
Genomic disorders are a clinically diverse group of conditions caused by gain, loss or re-orientation of a genomic region containing dosage-sensitive genes. One class of genomic disorder is caused by hemizygous deletions resulting in haploinsufficiency of a single or, more usually, several genes. For example, the heterozygous contiguous gene deletion on chromosome 22q11.2 causing DiGeorge syndrome involves at least 20-30 genes. Determining how the copy number variation (CNV) affects human variation and contributes to the aetiology and progression of various genomic disorders represents important questions for the future. Here, I will discuss the functional significance of one form of CNV, haploinsufficiency (i.e. loss of a gene copy), of DNA damage response components and its association with certain genomic disorders. There is increasing evidence that haploinsufficiency for certain genes encoding key players in the cells response to DNA damage, particularly those of the Ataxia Telangiectasia and Rad3-related (ATR)-pathway, has a functional impact. I will review this evidence and present examples of some well known clinically similar genomic disorders that have recently been shown to be defective in the ATR-dependent DNA damage response. Finally, I will discuss the potential implications of a haploinsufficiency-induced defective DNA damage response for the clinical management of certain human genomic disorders.
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Affiliation(s)
- Mark O'Driscoll
- Genome Damage & Stability Centre, University of Sussex, Falmer, Brighton, East Sussex, BN1 9RQ, UK
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34
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Chromosomal instability at the 7q11.23 region impacts on DNA-damage response in lymphocytes from Williams-Beuren syndrome patients. Mutat Res 2011; 724:46-51. [PMID: 21645633 DOI: 10.1016/j.mrgentox.2011.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 04/22/2011] [Accepted: 05/08/2011] [Indexed: 11/21/2022]
Abstract
Williams-Beuren syndrome (WBS) is the chromosomal disorder arising from a hemizygous microdeletion at 7q11.23. The present study was focused on a comparative investigation of genomic integrity in WBS patients by use of cytogenetic methods and the alkaline comet assay. Lymphocytes of whole peripheral blood were cultured and metaphases were examined for frequency and spectrum of chromosome aberrations. A WBS-related microdeletion was detected by means of the FISH (fluorescence in situ hybridization) technique. The blood samples from patients who were carriers of this microdeletion, were tested in the comet assay. For this purpose, freshly collected lymphocytes were exposed to hydrogen peroxide (100μM, 1min, 4°C). The frequencies of endogenous and exogenous DNA damage, and the kinetics and efficiency of DNA repair were measured during three subsequent hours of incubation. Comparison of the two data sets in this group of patients demonstrated a slightly elevated average frequency of chromosome aberrations, significantly increased levels of endogenous and H(2)O(2)-induced DNA damage, and somewhat impaired DNA repair. The relationship between an abnormal DNA-damage response and the 7q11.23 hemizygous microdeletion was confirmed experimentally when comparing the comet assay data in FISH-positive and FISH-negative lymphocytes from WBS-suspected patients. Briefly, our results indicate the impact of chromosomal instability within this region on susceptibility towards DNA damage, which may contribute to pathogenesis of this disease. It was shown also that the comet assay, as well as an experimental design proposed here, seem to be useful tools for estimating genome integrity in WBS patients.
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35
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Lim BC, Park WY, Seo EJ, Kim KJ, Hwang YS, Chae JH. De novo interstitial deletion of 3q22.3-q25.2 encompassing FOXL2, ATR, ZIC1, and ZIC4 in a patient with blepharophimosis/ptosis/epicanthus inversus syndrome, Dandy-Walker malformation, and global developmental delay. J Child Neurol 2011; 26:615-8. [PMID: 21471554 DOI: 10.1177/0883073810384996] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We report a case carrying a de novo interstitial deletion of chromosome 3q22-q25. The clinical phenotype of this case included blepharophimosis/ptosis/epicanthus inversus syndrome, Dandy-Walker malformation, and global developmental delay. Contiguous heterozygous deletion of FOXL2, ATR, ZIC1, and ZIC4 was postulated as the causative mechanism of the clinical phenotype. The association of blepharophimosis, ptosis, and epicanthus inversus syndrome with developmental delay or mental retardation may be an indication for the use of brain imaging and chromosomal analysis capable of detecting chromosomal rearrangements encompassing several candidate genes.
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Affiliation(s)
- Byung Chan Lim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Korea
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36
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de Clare M, Pir P, Oliver SG. Haploinsufficiency and the sex chromosomes from yeasts to humans. BMC Biol 2011; 9:15. [PMID: 21356089 PMCID: PMC3058074 DOI: 10.1186/1741-7007-9-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 02/28/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Haploinsufficient (HI) genes are those for which a reduction in copy number in a diploid from two to one results in significantly reduced fitness. Haploinsufficiency is increasingly implicated in human disease, and so predicting this phenotype could provide insights into the genetic mechanisms behind many human diseases, including some cancers. RESULTS In the present work we show that orthologues of Saccharomyces cerevisiae HI genes are preferentially retained across the kingdom Fungi, and that the HI genes of S. cerevisiae can be used to predict haploinsufficiency in humans. Our HI gene predictions confirm known associations between haploinsufficiency and genetic disease, and predict several further disorders in which the phenotype may be relevant. Haploinsufficiency is also clearly relevant to the gene-dosage imbalances inherent in eukaryotic sex-determination systems. In S. cerevisiae, HI genes are over-represented on chromosome III, the chromosome that determines yeast's mating type. This may be a device to select against the loss of one copy of chromosome III from a diploid. We found that orthologues of S. cerevisiae HI genes are also over-represented on the mating-type chromosomes of other yeasts and filamentous fungi. In animals with heterogametic sex determination, accumulation of HI genes on the sex chromosomes would compromise fitness in both sexes, given X chromosome inactivation in females. We found that orthologues of S. cerevisiae HI genes are significantly under-represented on the X chromosomes of mammals and of Caenorhabditis elegans. There is no X inactivation in Drosophila melanogaster (increased expression of X in the male is used instead) and, in this species, we found no depletion of orthologues to yeast HI genes on the sex chromosomes. CONCLUSION A special relationship between HI genes and the sex/mating-type chromosome extends from S. cerevisiae to Homo sapiens, with the microbe being a useful model for species throughout the evolutionary range. Furthermore, haploinsufficiency in yeast can predict the phenotype in higher organisms.
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Affiliation(s)
- Michaela de Clare
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, Sanger Building, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Pınar Pir
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, Sanger Building, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Stephen G Oliver
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, Sanger Building, 80 Tennis Court Road, Cambridge CB2 1GA, UK
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Poot M, van der Smagt J, Brilstra E, Bourgeron T. Disentangling the Myriad Genomics of Complex Disorders, Specifically Focusing on Autism, Epilepsy, and Schizophrenia. Cytogenet Genome Res 2011; 135:228-40. [DOI: 10.1159/000334064] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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Bohgaki T, Bohgaki M, Hakem R. DNA double-strand break signaling and human disorders. Genome Integr 2010; 1:15. [PMID: 21054854 PMCID: PMC2993650 DOI: 10.1186/2041-9414-1-15] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 11/05/2010] [Indexed: 12/20/2022] Open
Abstract
DNA double-strand breaks are among the most serious types of DNA damage and their signaling and repair is critical for all cells and organisms. The repair of both induced and programmed DNA breaks is fundamental as demonstrated by the many human syndromes, neurodegenerative diseases, immunodeficiency and cancer associated with defective repair of these DNA lesions. Homologous recombination and non-homologous end-joining pathways are the two major DNA repair pathways responsible for mediating the repair of DNA double-strand breaks. The signaling of DNA double-strand breaks is critical for cells to orchestrate the repair pathways and maintain genomic integrity. This signaling network is highly regulated and involves a growing number of proteins and elaborated posttranslational modifications including phosphorylation and ubiquitylation. Here, we highlight the recent progress in the signaling of DNA double-strand breaks, the major proteins and posttranslational modifications involved and the diseases and syndromes associated with impaired signaling of these breaks.
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Affiliation(s)
- Toshiyuki Bohgaki
- Ontario Cancer Institute, University Health Network and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, M5G 2M9 Ontario, Canada
| | - Miyuki Bohgaki
- Ontario Cancer Institute, University Health Network and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, M5G 2M9 Ontario, Canada
| | - Razqallah Hakem
- Ontario Cancer Institute, University Health Network and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, M5G 2M9 Ontario, Canada
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Double strand break repair components are frequent targets of microsatellite instability in endometrial cancer. Eur J Cancer 2010; 46:2821-7. [DOI: 10.1016/j.ejca.2010.06.116] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 06/18/2010] [Indexed: 11/22/2022]
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40
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Merla G, Brunetti-Pierri N, Micale L, Fusco C. Copy number variants at Williams–Beuren syndrome 7q11.23 region. Hum Genet 2010; 128:3-26. [DOI: 10.1007/s00439-010-0827-2] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Accepted: 04/13/2010] [Indexed: 01/06/2023]
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41
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Crespi B, Summers K, Dorus S. Evolutionary genomics of human intellectual disability. Evol Appl 2010; 3:52-63. [PMID: 25567903 PMCID: PMC3352458 DOI: 10.1111/j.1752-4571.2009.00098.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 07/28/2009] [Indexed: 01/28/2023] Open
Abstract
Previous studies have postulated that X-linked and autosomal genes underlying human intellectual disability may have also mediated the evolution of human cognition. We have conducted the first comprehensive assessment of the extent and patterns of positive Darwinian selection on intellectual disability genes in humans. We report three main findings. First, as noted in some previous reports, intellectual disability genes with primary functions in the central nervous system exhibit a significant concentration to the X chromosome. Second, there was no evidence for a higher incidence of recent positive selection on X-linked than autosomal intellectual disability genes, nor was there a higher incidence of selection on such genes overall, compared to sets of control genes. However, the X-linked intellectual disability genes inferred to be subject to recent positive selection were concentrated in the Rho GTP-ase pathway, a key signaling pathway in neural development and function. Third, among all intellectual disability genes, there was evidence for a higher incidence of recent positive selection on genes involved in DNA repair, but not for genes involved in other functions. These results provide evidence that alterations to genes in the Rho GTP-ase and DNA-repair pathways may play especially-important roles in the evolution of human cognition and vulnerability to genetically-based intellectual disability.
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Affiliation(s)
- Bernard Crespi
- Department of Biosciences, Simon Fraser UniversityBurnaby, BC, Canada
| | - Kyle Summers
- Department of Biology, East Carolina UniversityGreenville, NC, USA
| | - Steve Dorus
- Department of Biology and Biochemistry, University of BathBath, UK
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Ozgen HM, van Daalen E, Bolton PF, Maloney VK, Huang S, Cresswell L, van den Boogaard MJ, Eleveld MJ, van ‘t Slot R, Hochstenbach R, Beemer FA, Barrow M, Barber JCK, Poot M. Copy number changes of the microcephalin 1 gene (MCPH1) in patients with autism spectrum disorders. Clin Genet 2009; 76:348-56. [DOI: 10.1111/j.1399-0004.2009.01254.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Ragland RL, Arlt MF, Hughes ED, Saunders TL, Glover TW. Mice hypomorphic for Atr have increased DNA damage and abnormal checkpoint response. Mamm Genome 2009; 20:375-85. [PMID: 19504344 DOI: 10.1007/s00335-009-9195-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 05/08/2009] [Indexed: 10/20/2022]
Abstract
The ATR checkpoint pathway responds to DNA damage during the S/G2 phases of the cell cycle and is activated early in tumorigenesis. Investigation of ATR's role in development and tumorigenesis is complicated by the lethality of homozygous knockout mice and the limited effects of heterozygous deficiency. To overcome this limitation, we sought to create mice with a hypomorphic Atr mutation based on the ATR mutation in the human disease Seckel syndrome-1 (SCKL1). Homozygous SCKL1 mice were generated by targeted knock-in of the A --> G SCKL1 mutation. Western blot and RT-PCR analysis established that homozygotes have no reduction in Atr protein or increase in missplicing as is seen in humans. Thus, the A --> G substitution alone is not sufficient to reproduce in mice the effects that are seen in humans. However, homozygous SCKL1 mice that retain the neo cassette used for targeting have an estimated 66-82% reduction in total Atr protein levels due to missplicing into the neo cassette. Under conditions of APH-induced replication stress, primary fibroblasts from homozygous mice displayed an increase in overall chromosome damage and an increase in gaps and breaks at specific common fragile sites. In addition, mutant cells display a significant delay in checkpoint induction and an increase in DNA damage as assayed by Chk1 phosphorylation and gamma-H2ax levels, respectively. These mice provide a novel model system for studies of Atr deficiency and replication stress.
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Affiliation(s)
- Ryan L Ragland
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109-0618, USA.
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Waltes R, Kalb R, Gatei M, Kijas AW, Stumm M, Sobeck A, Wieland B, Varon R, Lerenthal Y, Lavin MF, Schindler D, Dörk T. Human RAD50 deficiency in a Nijmegen breakage syndrome-like disorder. Am J Hum Genet 2009; 84:605-16. [PMID: 19409520 PMCID: PMC2681000 DOI: 10.1016/j.ajhg.2009.04.010] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 03/13/2009] [Accepted: 04/09/2009] [Indexed: 01/24/2023] Open
Abstract
The MRE11/RAD50/NBN (MRN) complex plays a key role in recognizing and signaling DNA double-strand breaks (DSBs). Hypomorphic mutations in NBN (previously known as NBS1) and MRE11A give rise to the autosomal-recessive diseases Nijmegen breakage syndrome (NBS) and ataxia-telangiectasia-like disorder (ATLD), respectively. To date, no disease due to RAD50 deficiency has been described. Here, we report on a patient previously diagnosed as probably having NBS, with microcephaly, mental retardation, 'bird-like' face, and short stature. At variance with this diagnosis, she never had severe infections, had normal immunoglobulin levels, and did not develop lymphoid malignancy up to age 23 years. We found that she is compound heterozygous for mutations in the RAD50 gene that give rise to low levels of unstable RAD50 protein. Cells from the patient were characterized by chromosomal instability; radiosensitivity; failure to form DNA damage-induced MRN foci; and impaired radiation-induced activation of and downstream signaling through the ATM protein, which is defective in the human genetic disorder ataxia-telangiectasia. These cells were also impaired in G1/S cell-cycle-checkpoint activation and displayed radioresistant DNA synthesis and G2-phase accumulation. The defective cellular phenotype was rescued by wild-type RAD50. In conclusion, we have identified and characterized a patient with a RAD50 deficiency that results in a clinical phenotype that can be classified as an NBS-like disorder (NBSLD).
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Affiliation(s)
- Regina Waltes
- Clinics of Obstetrics and Gynaecology, Hannover Medical School, D-30625 Hannover, Germany
- Institute of Radiation Oncology, Hannover Medical School, D-30625 Hannover, Germany
| | - Reinhard Kalb
- Department of Human Genetics, Biozentrum, University of Würzburg, D-97074 Würzburg, Germany
| | - Magtouf Gatei
- Queensland Institute of Medical Research, Royal Brisbane Hospital, Herston, Queensland 4029, Australia
| | - Amanda W. Kijas
- Queensland Institute of Medical Research, Royal Brisbane Hospital, Herston, Queensland 4029, Australia
| | - Markus Stumm
- Institute of Human Genetics, Otto von Guericke University, D-39120 Magdeburg, Germany
| | - Alexandra Sobeck
- Department of Human Genetics, Biozentrum, University of Würzburg, D-97074 Würzburg, Germany
| | - Britta Wieland
- Clinics of Obstetrics and Gynaecology, Hannover Medical School, D-30625 Hannover, Germany
- Institute of Radiation Oncology, Hannover Medical School, D-30625 Hannover, Germany
| | - Raymonda Varon
- Institute of Human Genetics, Alexander von Humboldt University, D-13353 Berlin, Germany
| | - Yaniv Lerenthal
- Department of Human Genetics and Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, 69978 Ramat Aviv, Israel
| | - Martin F. Lavin
- Queensland Institute of Medical Research, Royal Brisbane Hospital, Herston, Queensland 4029, Australia
- University of Queensland, Centre for Clinical Research, Royal Brisbane Hospital, Brisbane, Queensland 4029, Australia
| | - Detlev Schindler
- Department of Human Genetics, Biozentrum, University of Würzburg, D-97074 Würzburg, Germany
| | - Thilo Dörk
- Clinics of Obstetrics and Gynaecology, Hannover Medical School, D-30625 Hannover, Germany
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Andäng M, Lendahl U. Ion fluxes and neurotransmitters signaling in neural development. Curr Opin Neurobiol 2009; 18:232-6. [PMID: 18638551 DOI: 10.1016/j.conb.2008.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 06/19/2008] [Indexed: 01/09/2023]
Abstract
The brain develops and functions in a complex ionic milieu, which is a prerequisite for neurotransmitter function and neuronal signaling. Neurotransmitters and ion fluxes are, however, important not only in neuronal signaling, but also in the control of neural differentiation, and in this review, we highlight the recent advances in our understanding of how the gamma-amino butyric acid (GABA) neurotransmitter and ion fluxes are relevant for cell cycle control and neural differentiation. Conversely, proteins previously associated with ion transport across membranes have been endowed with novel ion-independent functions, and we discuss this in the context of gap junctions in cell adhesion and of the neuron-specific K(+)-Cl(-) cotransporter KCC2 in dendritic spine development. Collectively, these findings provide a richer and more complex picture of when ion fluxes are needed in neural development and when they are not.
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Affiliation(s)
- Michael Andäng
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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Crespi B, Summers K, Dorus S. Genomic sister-disorders of neurodevelopment: an evolutionary approach. Evol Appl 2009; 2:81-100. [PMID: 25567849 PMCID: PMC3352408 DOI: 10.1111/j.1752-4571.2008.00056.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2008] [Accepted: 11/26/2008] [Indexed: 02/06/2023] Open
Abstract
Genomic sister-disorders are defined here as diseases mediated by duplications versus deletions of the same region. Such disorders can provide unique information concerning the genomic underpinnings of human neurodevelopment because effects of diametric variation in gene copy number on cognitive and behavioral phenotypes can be inferred. We describe evidence from the literature on deletions versus duplications for the regions underlying the best-known human neurogenetic sister-disorders, including Williams syndrome, Velocardiofacial syndrome, and Smith-Magenis syndrome, as well as the X-chromosomal conditions Klinefelter and Turner syndromes. These data suggest that diametric copy-number alterations can, like diametric alterations to imprinted genes, generate contrasting phenotypes associated with autistic-spectrum and psychotic-spectrum conditions. Genomically based perturbations to the development of the human social brain are thus apparently mediated to a notable degree by effects of variation in gene copy number. We also conducted the first analyses of positive selection for genes in the regions affected by these disorders. We found evidence consistent with adaptive evolution of protein-coding genes, or selective sweeps, for three of the four sets of sister-syndromes analyzed. These studies of selection facilitate identification of candidate genes for the phenotypes observed and lend a novel evolutionary dimension to the analysis of human cognitive architecture and neurogenetic disorders.
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Affiliation(s)
- Bernard Crespi
- Department of Biosciences, Simon Fraser University Burnaby, BC, Canada
| | - Kyle Summers
- Department of Biology, East Carolina University Greenville, NC, USA
| | - Steve Dorus
- Department of Biology and Biochemistry, University of Bath Bath, UK
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Collis SJ, Ciccia A, Deans AJ, Horejsí Z, Martin JS, Maslen SL, Skehel JM, Elledge SJ, West SC, Boulton SJ. FANCM and FAAP24 function in ATR-mediated checkpoint signaling independently of the Fanconi anemia core complex. Mol Cell 2008; 32:313-24. [PMID: 18995830 DOI: 10.1016/j.molcel.2008.10.014] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 07/19/2008] [Accepted: 10/20/2008] [Indexed: 10/21/2022]
Abstract
The Fanconi anemia (FA) pathway is implicated in DNA repair and cancer predisposition. Central to this pathway is the FA core complex, which is targeted to chromatin by FANCM and FAAP24 following replication stress. Here we show that FANCM and FAAP24 interact with the checkpoint protein HCLK2 independently of the FA core complex. In addition to defects in FA pathway activation, downregulation of FANCM or FAAP24 also compromises ATR/Chk1-mediated checkpoint signaling, leading to defective Chk1, p53, and FANCE phosphorylation; 53BP1 focus formation; and Cdc25A degradation. As a result, FANCM and FAAP24 deficiency results in increased endogenous DNA damage and a failure to efficiently invoke cell-cycle checkpoint responses. Moreover, we find that the DNA translocase activity of FANCM, which is dispensable for FA pathway activation, is required for its role in ATR/Chk1 signaling. Our data suggest that DNA damage recognition and remodeling activities of FANCM and FAAP24 cooperate with ATR/Chk1 to promote efficient activation of DNA damage checkpoints.
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Affiliation(s)
- Spencer J Collis
- DNA Damage Response Laboratory, Cancer Research UK, Clare Hall, EN6 3LD South Mimms, UK
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Stiff T, Cerosaletti K, Concannon P, O'Driscoll M, Jeggo PA. Replication independent ATR signalling leads to G2/M arrest requiring Nbs1, 53BP1 and MDC1. Hum Mol Genet 2008; 17:3247-53. [PMID: 18664457 DOI: 10.1093/hmg/ddn220] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ataxia telangiectasia and Rad3-related (ATR) is a phosphoinositol-3-kinase like kinase (PIKK) that initiates a signal transduction response to replication fork stalling. Defects in ATR signalling have been reported in several disorders characterized by microcephaly and growth delay. Here, we gain insight into factors influencing the ATR signalling pathway and consider how they can be exploited for diagnostic purposes. Activation of ATR at stalled replication forks leads to intra-S and G2/M phase checkpoint arrest. ATR also phosphorylates gamma-H2AX at single-stranded (ss) DNA regions generated during nucleotide excision repair (NER) in non-replicating cells, but the critical analysis of any functional consequence has not been reported. Here, we show that UV irradiation of G2 phase cells causes ATR-dependent but replication-independent G2/M checkpoint arrest. This process requires the Nbs1 N-terminus encompassing the FHA and BRCT domains but not the Nbs1 C-terminus in contrast to ATM-dependent activation of G2/M arrest in response to ionizing radiation. Thus, Nbs1 has a function in ATR signalling in a manner distinct to any role at stalled replication forks. Replication-independent ATR signalling also requires the mediator proteins, 53BP1 and MDC1, providing direct evidence for their role in ATR signalling, but not H2AX. Finally, the process is activated in Cockayne's syndrome but not Xeroderma pigmentosum group A cells providing evidence that ssDNA regions generated during NER are the ATR-pathway-specific activating lesion. Replication-independent G2/M checkpoint arrest represents a suitable assay to specifically identify patients with defective ATR signalling, including Seckel syndrome, Nijmegen breakage syndrome and MCPH-1-dependent primary microcephaly.
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Affiliation(s)
- Tom Stiff
- Genome Damage and Stability Centre, University of Sussex, Brighton, East Sussex BN1 9RQ, UK
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Barzilai A, Biton S, Shiloh Y. The role of the DNA damage response in neuronal development, organization and maintenance. DNA Repair (Amst) 2008; 7:1010-27. [DOI: 10.1016/j.dnarep.2008.03.005] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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50
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O'Driscoll M, Jeggo PA. The role of the DNA damage response pathways in brain development and microcephaly: insight from human disorders. DNA Repair (Amst) 2008; 7:1039-50. [PMID: 18458003 DOI: 10.1016/j.dnarep.2008.03.018] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A network of DNA damage response (DDR) mechanisms functions co-ordinately to maintain genomic stability and ensure cellular survival in the face of exogenous and endogenous DNA damage. Defects in DDR pathways have been identified in a range of human disorders, collectively classified as DDR-defective syndromes. A common feature of these syndromes is a predisposition to cancer demonstrating the importance of the DDR in cancer avoidance. How the DDR mechanisms serve to maintain genomic stability has been the predominant focus of research into their function. However, many DRR-defective syndromes are also characterised by impaired development demonstrating broader roles for the DDR mechanisms. Microcephaly, representing reduced brain size, is a feature common to a diverse range of DDR-defective disorders. Microcephaly is most likely caused by loss (increased cell death) or failure of the developing neuronal stem cells or their progenitors to divide suggesting a fundamental role for the DDR in maintaining proliferative potential in the developing nervous system. Currently, it is unclear why the DDR proteins should be more important during neuronal development compared with the development of other tissues or why the embryonic brain is more sensitive than the adult brain. Here, we overview the DDR-defective disorders in the context of microcephaly and discuss a model underlying this striking phenotype.
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Affiliation(s)
- Mark O'Driscoll
- Genome Damage and Stability Centre, University of Sussex, Brighton, East Sussex BN1 9RQ, UK.
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