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Martins DJ, Di Lazzaro Filho R, Bertola DR, Hoch NC. Rothmund-Thomson syndrome, a disorder far from solved. FRONTIERS IN AGING 2023; 4:1296409. [PMID: 38021400 PMCID: PMC10676203 DOI: 10.3389/fragi.2023.1296409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023]
Abstract
Rothmund-Thomson syndrome (RTS) is a rare autosomal recessive disorder characterized by a range of clinical symptoms, including poikiloderma, juvenile cataracts, short stature, sparse hair, eyebrows/eyelashes, nail dysplasia, and skeletal abnormalities. While classically associated with mutations in the RECQL4 gene, which encodes a DNA helicase involved in DNA replication and repair, three additional genes have been recently identified in RTS: ANAPC1, encoding a subunit of the APC/C complex; DNA2, which encodes a nuclease/helicase involved in DNA repair; and CRIPT, encoding a poorly characterized protein implicated in excitatory synapse formation and splicing. Here, we review the clinical spectrum of RTS patients, analyze the genetic basis of the disease, and discuss molecular functions of the affected genes, drawing some novel genotype-phenotype correlations and proposing avenues for future studies into this enigmatic disorder.
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Affiliation(s)
- Davi Jardim Martins
- Genomic Stability Unit, Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Ricardo Di Lazzaro Filho
- Center for Human Genome Studies, Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
- Dasa Genômica/Genera, Genômica, São Paulo, Brazil
| | - Debora Romeo Bertola
- Center for Human Genome Studies, Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
- Genetics Unit, Department of Pediatrics, Faculty of Medicine, Children’s Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Nícolas Carlos Hoch
- Genomic Stability Unit, Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
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Xu X, Chang CW, Li M, Liu C, Liu Y. Molecular Mechanisms of the RECQ4 Pathogenic Mutations. Front Mol Biosci 2021; 8:791194. [PMID: 34869606 PMCID: PMC8637615 DOI: 10.3389/fmolb.2021.791194] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 11/02/2021] [Indexed: 12/03/2022] Open
Abstract
The human RECQ4 gene encodes an ATP-dependent DNA helicase that contains a conserved superfamily II helicase domain located at the center of the polypeptide. RECQ4 is one of the five RECQ homologs in human cells, and its helicase domain is flanked by the unique amino and carboxyl termini with sequences distinct from other members of the RECQ helicases. Since the identification of the RECQ4 gene in 1998, multiple RECQ4 mutations have been linked to the pathogenesis of three clinical diseases, which are Rothmund-Thomson syndrome, Baller-Gerold syndrome, and RAPADILINO. Patients with these diseases show various developmental abnormalities. In addition, a subset of RECQ4 mutations are associated with high cancer risks, especially for osteosarcoma and/or lymphoma at early ages. The discovery of clinically relevant RECQ4 mutations leads to intriguing questions: how is the RECQ4 helicase responsible for preventing multiple clinical syndromes? What are the mechanisms by which the RECQ4 disease mutations cause tissue abnormalities and drive cancer formation? Furthermore, RECQ4 is highly overexpressed in many cancer types, raising the question whether RECQ4 acts not only as a tumor suppressor but also an oncogene that can be a potential new therapeutic target. Defining the molecular dysfunctions of different RECQ4 disease mutations is imperative to improving our understanding of the complexity of RECQ4 clinical phenotypes and the dynamic roles of RECQ4 in cancer development and prevention. We will review recent progress in examining the molecular and biochemical properties of the different domains of the RECQ4 protein. We will shed light on how the dynamic roles of RECQ4 in human cells may contribute to the complexity of RECQ4 clinical phenotypes.
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Affiliation(s)
- Xiaohua Xu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, United States
| | - Chou-Wei Chang
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, United States
| | - Min Li
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, United States
| | - Chao Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, United States
| | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, United States
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Schmit M, Bielinsky AK. Congenital Diseases of DNA Replication: Clinical Phenotypes and Molecular Mechanisms. Int J Mol Sci 2021; 22:E911. [PMID: 33477564 PMCID: PMC7831139 DOI: 10.3390/ijms22020911] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 12/19/2022] Open
Abstract
Deoxyribonucleic acid (DNA) replication can be divided into three major steps: initiation, elongation and termination. Each time a human cell divides, these steps must be reiteratively carried out. Disruption of DNA replication can lead to genomic instability, with the accumulation of point mutations or larger chromosomal anomalies such as rearrangements. While cancer is the most common class of disease associated with genomic instability, several congenital diseases with dysfunctional DNA replication give rise to similar DNA alterations. In this review, we discuss all congenital diseases that arise from pathogenic variants in essential replication genes across the spectrum of aberrant replisome assembly, origin activation and DNA synthesis. For each of these conditions, we describe their clinical phenotypes as well as molecular studies aimed at determining the functional mechanisms of disease, including the assessment of genomic stability. By comparing and contrasting these diseases, we hope to illuminate how the disruption of DNA replication at distinct steps affects human health in a surprisingly cell-type-specific manner.
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Affiliation(s)
| | - Anja-Katrin Bielinsky
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA;
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Lu L, Jin W, Wang LL. RECQ DNA Helicases and Osteosarcoma. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1258:37-54. [PMID: 32767233 DOI: 10.1007/978-3-030-43085-6_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The RECQ family of DNA helicases is a conserved group of enzymes that plays an important role in maintaining genomic stability. Humans possess five RECQ helicase genes, and mutations in three of them - BLM, WRN, and RECQL4 - are associated with the genetic disorders Bloom syndrome, Werner syndrome, and Rothmund-Thomson syndrome (RTS), respectively. These syndromes share overlapping clinical features, and importantly they are all associated with an increased risk of cancer. Patients with RTS have the highest specific risk of developing osteosarcoma compared to all other cancer predisposition syndromes; therefore, RTS serves as a relevant model to study the pathogenesis and molecular genetics of osteosarcoma. The "tumor suppressor" function of the RECQ helicases continues to be an area of active investigation. This chapter will focus primarily on the known cellular functions of RECQL4 and how these may relate to tumorigenesis, as well as ongoing efforts to understand RECQL4's functions in vivo using animal models. Understanding the RECQ pathways will provide insight into avenues for novel cancer therapies in the future.
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Affiliation(s)
- Linchao Lu
- Department of Pediatrics, Section of Hematology/Oncology, Texas Children's Cancer Center, Baylor College of Medicine, Houston, TX, USA.
| | - Weidong Jin
- Department of Pediatrics, Section of Hematology/Oncology, Texas Children's Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Lisa L Wang
- Department of Pediatrics, Section of Hematology/Oncology, Texas Children's Cancer Center, Baylor College of Medicine, Houston, TX, USA.
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Colombo EA, Locatelli A, Cubells Sánchez L, Romeo S, Elcioglu NH, Maystadt I, Esteve Martínez A, Sironi A, Fontana L, Finelli P, Gervasini C, Pecile V, Larizza L. Rothmund-Thomson Syndrome: Insights from New Patients on the Genetic Variability Underpinning Clinical Presentation and Cancer Outcome. Int J Mol Sci 2018; 19:E1103. [PMID: 29642415 PMCID: PMC5979380 DOI: 10.3390/ijms19041103] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 03/31/2018] [Accepted: 04/03/2018] [Indexed: 11/16/2022] Open
Abstract
Biallelic mutations in RECQL4 gene, a caretaker of the genome, cause Rothmund-Thomson type-II syndrome (RTS-II) and confer increased cancer risk if they damage the helicase domain. We describe five families exemplifying clinical and allelic heterogeneity of RTS-II, and report the effect of pathogenic RECQL4 variants by in silico predictions and transcripts analyses. Complete phenotype of patients #39 and #42 whose affected siblings developed osteosarcoma correlates with their c.[1048_1049del], c.[1878+32_1878+55del] and c.[1568G>C;1573delT], c.[3021_3022del] variants which damage the helicase domain. Literature survey highlights enrichment of these variants affecting the helicase domain in patients with cancer outcome raising the issue of strict oncological surveillance. Conversely, patients #29 and #19 have a mild phenotype and carry, respectively, the unreported homozygous c.3265G>T and c.3054A>G variants, both sparing the helicase domain. Finally, despite matching several criteria for RTS clinical diagnosis, patient #38 is heterozygous for c.2412_2414del; no pathogenic CNVs out of those evidenced by high-resolution CGH-array, emerged as contributors to her phenotype.
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Affiliation(s)
- Elisa A Colombo
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, 20142 Milan, Italy.
| | - Andrea Locatelli
- UO Dermatologia e Venereologia, Asst Papa Giovanni XXIII, 24127 Bergamo, Italy.
| | - Laura Cubells Sánchez
- Department of Dermatology, Consorcio Hospital General Universitario de Valencia, 46014 Valencia, Spain.
| | - Sara Romeo
- Institute of Clinical Sciences, Imperial College London, London W12 0NN, UK.
- MRC London Institute of Medical Sciences, Imperial College London, W12 0NN London, UK.
| | - Nursel H Elcioglu
- Department of Pediatric Genetics, Marmara University Medical School, 34890 Istanbul, Turkey.
- Department of Pediatrics, Eastern Mediterranean University, Mersin 10 Cyprus, Turkey.
| | - Isabelle Maystadt
- Centre de Génétique Humaine, Institut de Pathologie et de Génétique, 6041 Charleroi (Gosselies), Belgium.
| | - Altea Esteve Martínez
- Department of Dermatology, Consorcio Hospital General Universitario de Valencia, 46014 Valencia, Spain.
| | - Alessandra Sironi
- Laboratory of Medical Cytogenetics and Molecular Genetics, IRCCS Istituto Auxologico Italiano, 20149 Milan, Italy.
- Department of Medical Biotechnology and Translational Medicine, University of Milan, 20133 Milan, Italy.
| | - Laura Fontana
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, 20142 Milan, Italy.
| | - Palma Finelli
- Laboratory of Medical Cytogenetics and Molecular Genetics, IRCCS Istituto Auxologico Italiano, 20149 Milan, Italy.
- Department of Medical Biotechnology and Translational Medicine, University of Milan, 20133 Milan, Italy.
| | - Cristina Gervasini
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, 20142 Milan, Italy.
| | - Vanna Pecile
- Institute for Maternal and Child Health, Foundation IRCCS Burlo Garofolo Institute, 34137 Trieste, Italy.
| | - Lidia Larizza
- Laboratory of Medical Cytogenetics and Molecular Genetics, IRCCS Istituto Auxologico Italiano, 20149 Milan, Italy.
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Gui B, Song Y, Hu X, Li H, Qin Z, Su J, Li C, Fan X, Li M, Luo J, Feng Y, Song L, Chen S, Gong C, Shen Y. Novel pathogenic RECQL4 variants in Chinese patients with Rothmund-Thomson syndrome. Gene 2018; 654:110-115. [PMID: 29462647 DOI: 10.1016/j.gene.2018.02.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 02/06/2018] [Accepted: 02/16/2018] [Indexed: 11/30/2022]
Abstract
BACKGROUND Rothmund-Thomson syndrome (RTS) is a rare autosomal recessive disorder mainly characterized by cutaneous poikiloderma, sparse hair, short stature and skeletal defects. Deleterious mutations in the RecQ-like DNA helicase type 4 (RECQL4) gene have been detected in approximately two-thirds of RTS cases. METHODS Three Chinese patients from two unrelated families were enrolled for clinical evaluation. Targeted next-generation sequencing (NGS) using a custom panel consisting of 705 short-stature-related genes was performed for the probands. Variants detected by NGS were confirmed by Sanger sequencing and examined in family members. RESULTS The probands presented with characteristic features of severe growth delay, poikiloderma mostly on the face, buttocks and extremities, sparse or absent hair, eyelashes, and eyebrows, forearm reduction defects, small hands with hypoplasia of the middle phalanx (little finger) in one of the probands, epicanthus, hypertelorism, and dental abnormalities. In addition, novel auricle features and other rare facial features, including narrow palpebral fissure, depressed nasal bridge, and small chin were exhibited. Four novel RECQL4 variants were identified, including three pathogenic frameshift variants, c.1724_1725delAC, p.His575fs*7; c.2421dupT, p.Asp808*; c.1770_1807del, p.Pro591fs*2, and one likely pathogenic missense variant, c.691G>A, p.Gly231Ser. CONCLUSION Our study expands the mutational spectrum of RECQL4 gene and reveals novel phenotypes observed in Chinese RTS patients.
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Affiliation(s)
- Baoheng Gui
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China; Birth Defects Prevention and Control Institute of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Yanning Song
- National Center for Children's Health, China, Center of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, The Capital Medical University, Beijing 100045, PR China
| | - Xuyun Hu
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China; Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, PR China
| | - Hongdou Li
- Institute of Reproduction & Development, Hospital and Institute of Obstetrics & Gynecology, Fudan University, Shanghai 200011, PR China
| | - Zailong Qin
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China; Birth Defects Prevention and Control Institute of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Jiasun Su
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Chuan Li
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Xin Fan
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China; Birth Defects Prevention and Control Institute of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Mengting Li
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Jingsi Luo
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China; Birth Defects Prevention and Control Institute of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Ying Feng
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Liping Song
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China
| | - Shaoke Chen
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China; Birth Defects Prevention and Control Institute of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China.
| | - Chunxiu Gong
- National Center for Children's Health, China, Center of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital, The Capital Medical University, Beijing 100045, PR China.
| | - Yiping Shen
- Department of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China; Birth Defects Prevention and Control Institute of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530002, PR China; Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, PR China; Division of Genetics and Genomics, Boston Children's Hospital, Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, United States.
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Rogers CM, Wang JCY, Noguchi H, Imasaki T, Takagi Y, Bochman ML. Yeast Hrq1 shares structural and functional homology with the disease-linked human RecQ4 helicase. Nucleic Acids Res 2017; 45:5217-5230. [PMID: 28334827 PMCID: PMC5605238 DOI: 10.1093/nar/gkx151] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 02/22/2017] [Indexed: 12/14/2022] Open
Abstract
The five human RecQ helicases participate in multiple processes required to maintain genome integrity. Of these, the disease-linked RecQ4 is the least studied because it poses many technical challenges. We previously demonstrated that the yeast Hrq1 helicase displays similar functions to RecQ4 in vivo, and here, we report the biochemical and structural characterization of these enzymes. In vitro, Hrq1 and RecQ4 are DNA-stimulated ATPases and robust helicases. Further, these activities were sensitive to DNA sequence and structure, with the helicases preferentially unwinding D-loops. Consistent with their roles at telomeres, telomeric repeat sequence DNA also stimulated binding and unwinding by these enzymes. Finally, electron microscopy revealed that Hrq1 and RecQ4 share similar structural features. These results solidify Hrq1 as a true RecQ4 homolog and position it as the premier model to determine how RecQ4 mutations lead to genomic instability and disease.
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Affiliation(s)
- Cody M Rogers
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | | | - Hiroki Noguchi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Tsuyoshi Imasaki
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yuichiro Takagi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Matthew L Bochman
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
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Giordano CN, Yew YW, Spivak G, Lim HW. Understanding photodermatoses associated with defective DNA repair: Syndromes with cancer predisposition. J Am Acad Dermatol 2017; 75:855-870. [PMID: 27745641 DOI: 10.1016/j.jaad.2016.03.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 03/09/2016] [Accepted: 03/11/2016] [Indexed: 01/11/2023]
Abstract
Hereditary photodermatoses are a spectrum of rare photosensitive disorders that are often caused by genetic deficiency or malfunction of various components of the DNA repair pathway. This results clinically in extreme photosensitivity, with many syndromes exhibiting an increased risk of cutaneous malignancies. This review will focus specifically on the syndromes with malignant potential, including xeroderma pigmentosum, Bloom syndrome, and Rothmund-Thomson syndrome. The typical phenotypic findings of each disorder will be examined and contrasted, including noncutaneous identifiers to aid in diagnosis. The management of these patients will also be discussed. At this time, the mainstay of therapy remains strict photoprotection; however, genetic therapies are under investigation.
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Affiliation(s)
| | - Yik Weng Yew
- Department of Dermatology, National Skin Centre, Singapore
| | - Graciela Spivak
- Department of Biology, Stanford University, Stanford, California
| | - Henry W Lim
- Department of Dermatology, Henry Ford Hospital, Detroit, Michigan.
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Suter AA, Itin P, Heinimann K, Ahmed M, Ashraf T, Fryssira H, Kini U, Lapunzina P, Miny P, Sommerlund M, Suri M, Vaeth S, Vasudevan P, Gallati S. Rothmund-Thomson Syndrome: novel pathogenic mutations and frequencies of variants in the RECQL4 and USB1 (C16orf57) gene. Mol Genet Genomic Med 2016; 4:359-66. [PMID: 27247962 PMCID: PMC4867568 DOI: 10.1002/mgg3.209] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 01/23/2016] [Accepted: 01/27/2016] [Indexed: 01/17/2023] Open
Abstract
Background Poikiloderma is defined as a chronic skin condition presenting with a combination of punctate atrophy, areas of depigmentation, hyperpigmentation and telangiectasia. In a variety of hereditary syndromes such as Rothmund–Thomson syndrome (RTS), Clericuzio‐type poikiloderma with neutropenia (PN) and Dyskeratosis Congenita (DC), poikiloderma occurs as one of the main symptoms. Here, we report on genotype and phenotype data of a cohort of 44 index patients with RTS or related genodermatoses. Methods DNA samples from 43 patients were screened for variants in the 21 exons of the RECQL4 gene using PCR, SSCP‐PAGE analysis and/or Sanger sequencing. Patients with only one or no detectable mutation in the RECQL4 gene were additionally tested for variants in the 8 exons of the USB1 (C16orf57) gene by Sanger sequencing. The effect of novel variants was evaluated by phylogenic studies, single‐nucleotide polymorphism (SNP) databases and in silico analyses. Results We identified 23 different RECQL4 mutations including 10 novel and one homozygous novel USB1 (C16orf57) mutation in a patient with PN. Moreover, we describe 31 RECQL4 and 8 USB1 sequence variants, four of them being novel intronic RECQL4 sequence changes that may have some deleterious effects on splicing mechanisms and need further evaluation by transcript analyses. Conclusion The current study contributes to the improvement of genetic diagnostic strategies and interpretation in RTS and PN that is relevant in order to assess the patients' cancer risk, to avoid continuous and inconclusive clinical evaluations and to clarify the recurrence risk in the families. Additionally, it shows that the phenotype of more than 50% of the patients with suspected Rothmund–Thomson disease may be due to mutations in other genes raising the need for further extended genetic analyses.
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Affiliation(s)
- Aude-Annick Suter
- Division of Human GeneticsDepartment of PaediatricsInselspitalUniversity of BernCH-3010BernSwitzerland; Department of Clinical ResearchUniversity of BernCH-3010BernSwitzerland
| | - Peter Itin
- Department of Dermatology University of Basel Basel Switzerland
| | - Karl Heinimann
- Medical Genetics University Hospital Basel Basel Switzerland
| | - Munaza Ahmed
- Wessex Clinical Genetics Service University Hospital Southampton Southampton UK
| | - Tazeen Ashraf
- Department of Clinical Genetics Guys Hospital London UK
| | - Helen Fryssira
- Department of Clinical Genetics Agia Sophia Children's Hospital Athens Greece
| | - Usha Kini
- Department of Clinical Genetics Oxford University Hospitals NHS Trust Oxford UK
| | - Pablo Lapunzina
- INGEMM, Institute of Medical and Molecular Genetics University Hospital La Paz, IdiPAZ-CIBERER Madrid Spain
| | - Peter Miny
- Medical Genetics University Hospital Basel Basel Switzerland
| | - Mette Sommerlund
- Department of Dermatology Aarhus University Hospital Aarhus Denmark
| | - Mohnish Suri
- Departement of Clinical Genetics Nottingham University Hospitals NHS Trust City Hospital Campus Nottingham UK
| | - Signe Vaeth
- Department of Clinical Genetics Aarhus University Hospital Aarhus Denmark
| | - Pradeep Vasudevan
- Department of Clinical Genetics University Hospitals of Leicester NHS Trust Leicester Royal Infirmary Leicester UK
| | - Sabina Gallati
- Division of Human GeneticsDepartment of PaediatricsInselspitalUniversity of BernCH-3010BernSwitzerland; Department of Clinical ResearchUniversity of BernCH-3010BernSwitzerland
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Zils K, Klingebiel T, Behnisch W, Mueller HL, Schlegel PG, Fruehwald M, Suttorp M, Simon T, Werner M, Bielack S. Osteosarcoma in patients with Rothmund-Thomson syndrome. Pediatr Hematol Oncol 2015; 32:32-40. [PMID: 25551679 DOI: 10.3109/08880018.2014.987939] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND Rothmund-Thomson syndrome (RTS) is associated with an increased risk of osteosarcoma, but information about affected patients is limited. PROCEDURE Seven patients with osteosarcoma, treated in the Cooperative Osteosarcoma Study Group-trials, had a diagnosis of RTS. Their patient-, tumor- and treatment-related variables and outcome were reviewed retrospectively. RESULTS Median age at diagnosis of osteosarcoma was 13 years (range 7-16), five were female, two male. Tumor involved proximal tibia (n = 4), distal tibia (n = 1), distal fibula (n = 1) and proximal ulna (n = 1). Three patients had metastatic disease at diagnosis. All patients received surgery and chemotherapy. Four of seven patients required dose modifications and three of them terminated treatment prematurely. Complete resection of the primary tumor was achieved in all individuals. Two of three affected patients failed to achieve surgical clearance of their primary metastases and died. The third patient relapsed with multiple metastases and died. Two of four patients with localized disease were alive in first complete remission, a third patient in second complete remission after recurrence and a fourth patient died of acute leukemia, while still in first complete remission of osteosarcoma. CONCLUSIONS Patients with RTS and osteosarcoma may be cured of their cancer with appropriate multimodal therapy. They should be treated like other osteosarcoma patients but preexisting disorders, needs for special support and development of toxicities have to be considered.
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Affiliation(s)
- Katja Zils
- 1Cooperative Osteosarcoma Study Group (COSS), Pediatrics 5 (Oncology, Hematology, Immunology), Klinikum Stuttgart-Olgahospital , Germany
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11
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Novel physiological RECQL4 alternative transcript disclosed by molecular characterisation of Rothmund-Thomson Syndrome sibs with mild phenotype. Eur J Hum Genet 2014; 22:1298-304. [PMID: 24518840 DOI: 10.1038/ejhg.2014.18] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 11/15/2013] [Accepted: 01/07/2014] [Indexed: 01/21/2023] Open
Abstract
Rothmund-Thomson syndrome is a rare genodermatosis caused by biallelic mutations of the RECQL4 gene and is characterised by poikiloderma, sparse hair, eyelashes and/or eyebrows, small stature, skeletal and dental abnormalities and cancer predisposition. Mutations predicted to result in the loss of RECQL4 protein have been associated with osteosarcoma risk, but mutation(s)-phenotype correlations are better addressed by combined DNA and RNA analyses. We describe two siblings with a mild phenotype, mainly restricted to the skin, who carry the unreported paternal c.2272C>T alteration in exon 14 and the previously reported maternal exon 15 c.2492_2493delAT, both predicted to result in premature termination codons (p.(Arg758*), p.(His831Argfs*52)). However real-time and transcript analysis showed, in the carrier father and affected daughter, increased levels of a novel RECQL4 physiological alternative transcript with partial in-frame skipping of exon 14, generated by increased usage of a weak cryptic splice site. This alternative transcript is expressed in all controls and tested tissues, its upregulation is specific to the paternal c.2272C>T mutation and depends on the abrogation of the binding motifs for SF2 and SRp55 serine/arginine-rich proteins with bypass of the mutation site located in the skipped exon 14 portion. Moreover, in the proband the increased levels of the alternative transcript, likely encoding a protein isoform with residual activity, may compensate for the dearth of the canonical transcript with the c.2492_2493delAT, accounting for the mild clinical phenotype of the siblings. Our results emphasise the value of RNA analysis to better predict the effects of RECQL4 mutations on the clinical phenotype.
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12
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Abstract
The RECQ family of DNA helicases is a conserved group of enzymes that are important for maintaining genomic integrity. In humans, there are five RECQ helicase genes, and mutations in three of them-BLM, WRN, and RECQL4-are associated with the genetic disorders Bloom syndrome, Werner syndrome, and Rothmund-Thomson syndrome (RTS), respectively. Importantly all three diseases are cancer predisposition syndromes. Patients with RTS are highly and uniquely susceptible to developing osteosarcoma; thus, RTS provides a good model to study the pathogenesis of osteosarcoma. The "tumor suppressor" role of RECQL4 and the other RECQ helicases is an area of active investigation. This chapter reviews what is currently known about the cellular functions of RECQL4 and how these may relate to tumorigenesis, as well as ongoing efforts to understand RECQL4's functions in vivo using animal models. Understanding the RECQ pathways may provide insight into avenues for novel cancer therapies in the future.
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Davis T, Tivey HSE, Brook AJC, Grimstead JW, Rokicki MJ, Kipling D. Activation of p38 MAP kinase and stress signalling in fibroblasts from the progeroid Rothmund-Thomson syndrome. AGE (DORDRECHT, NETHERLANDS) 2013; 35:1767-83. [PMID: 23001818 PMCID: PMC3776094 DOI: 10.1007/s11357-012-9476-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 09/09/2012] [Indexed: 05/12/2023]
Abstract
Rothmund-Thomson fibroblasts had replicative lifespans and growth rates within the range for normal fibroblasts; however, they show elevated levels of the stress-associated p38 MAP kinase, suggestive of stress during growth. Treatment with the p38 MAP kinase inhibitor SB203580 increased both lifespan and growth rate, as did reduction of oxidative stress using low oxygen in some strains. At replicative senescence p53, p21(WAF1) and p16(INK4A) levels were elevated, and abrogation of p53 using shRNA knockdown allowed the cells to bypass senescence. Ectopic expression of human telomerase allowed Rothmund-Thomson fibroblasts to bypass senescence. However, activated p38 was still present, and continuous growth for some telomerised clones required either a reduction in oxidative stress or SB203580 treatment. Overall, the evidence suggests that replicative senescence in Rothmund-Thomson cells resembles normal senescence in that it is telomere driven and p53 dependent. However, the lack of RECQL4 leads to enhanced levels of stress during cell growth that may lead to moderate levels of stress-induced premature senescence. As replicative senescence is believed to underlie human ageing, a moderate level of stress-induced premature senescence and p38 activity may play a role in the relatively mild ageing phenotype seen in Rothmund-Thomson.
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Affiliation(s)
- Terence Davis
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK,
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14
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Crevel G, Vo N, Crevel I, Hamid S, Hoa L, Miyata S, Cotterill S. Drosophila RecQ4 is directly involved in both DNA replication and the response to UV damage in S2 cells. PLoS One 2012; 7:e49505. [PMID: 23166690 PMCID: PMC3500301 DOI: 10.1371/journal.pone.0049505] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 10/10/2012] [Indexed: 11/18/2022] Open
Abstract
The RecQ4 protein shows homology to both the S.cerevisiae DNA replication protein Sld2 and the DNA repair related RecQ helicases. Experimental data also suggest replication and repair functions for RecQ4, but the precise details of its involvement remain to be clarified. Here we show that depletion of DmRecQ4 by dsRNA interference in S2 cells causes defects consistent with a replication function for the protein. The cells show reduced proliferation associated with an S phase block, reduced BrdU incorporation, and an increase in cells with a subG1 DNA content. At the molecular level we observe reduced chromatin association of DNA polymerase-alpha and PCNA. We also observe increased chromatin association of phosphorylated H2AvD - consistent with the presence of DNA damage and increased apoptosis. Analysis of DmRecQ4 repair function suggests a direct role in NER, as the protein shows rapid but transient nuclear localisation after UV treatment. Re-localisation is not observed after etoposide or H2O2 treatment, indicating that the involvement of DmRecQ4 in repair is likely to be pathway specific. Deletion analysis of DmRecQ4 suggests that the SLD2 domain was essential, but not sufficient, for replication function. In addition a DmRecQ4 N-terminal deletion could efficiently re-localise on UV treatment, suggesting that the determinants for this response are contained in the C terminus of the protein. Finally several deletions show differential rescue of dsRNA generated replication and proliferation phenotypes. These will be useful for a molecular analysis of the specific role of DmRecQ4 in different cellular pathways.
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Affiliation(s)
- Gilles Crevel
- Department Basic Medical Sciences, St. Georges University London, Cranmer Terrace, London, United Kingdom
| | - Nicole Vo
- Department Basic Medical Sciences, St. Georges University London, Cranmer Terrace, London, United Kingdom
| | - Isabelle Crevel
- Department Basic Medical Sciences, St. Georges University London, Cranmer Terrace, London, United Kingdom
| | - Sana Hamid
- Department Basic Medical Sciences, St. Georges University London, Cranmer Terrace, London, United Kingdom
| | - Lily Hoa
- Department Basic Medical Sciences, St. Georges University London, Cranmer Terrace, London, United Kingdom
| | - Seiji Miyata
- Department Basic Medical Sciences, St. Georges University London, Cranmer Terrace, London, United Kingdom
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan
| | - Sue Cotterill
- Department Basic Medical Sciences, St. Georges University London, Cranmer Terrace, London, United Kingdom
- * E-mail:
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15
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Kohzaki M, Chiourea M, Versini G, Adachi N, Takeda S, Gagos S, Halazonetis TD. The helicase domain and C-terminus of human RecQL4 facilitate replication elongation on DNA templates damaged by ionizing radiation. Carcinogenesis 2012; 33:1203-10. [PMID: 22508716 DOI: 10.1093/carcin/bgs149] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The vertebrate RECQL4 (RECQ4) gene is thought to be the ortholog of budding yeast SLD2. However, RecQL4 contains within its C-terminus a RecQ-like helicase domain, which is absent in Sld2. We established human pre-B lymphocyte Nalm-6 cells, in which the endogenous RECQL4 gene was homozygously targeted such that the entire C-terminus would not be expressed. The RECQL4(ΔC/ΔC) cells behaved like the parental cells during unperturbed DNA replication or after treatment with agents that induce stalling of DNA replication forks, such as hydroxyurea (HU). However, after exposure to ionizing radiation (IR), the RECQL4(ΔC/ΔC) cells exhibited hypersensitivity, inability to complete S phase and prematurely terminated or paused DNA replication forks. Deletion of BLM, a gene that also encodes a RecQ helicase, had the opposite phenotype; an almost wild-type response to IR, but hypersensitivity to HU. Targeting both RECQL4 and BLM resulted in viable cells, which exhibited mostly additive phenotypes compared with those exhibited by the RECQL4(ΔC/ΔC) and the BLM(-/-) cells. We propose that RecQL4 facilitates DNA replication in cells that have been exposed to IR.
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Affiliation(s)
- Masaoki Kohzaki
- Department of Molecular Biology, University of Geneva, Switzerland
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16
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Ghosh AK, Rossi ML, Singh DK, Dunn C, Ramamoorthy M, Croteau DL, Liu Y, Bohr VA. RECQL4, the protein mutated in Rothmund-Thomson syndrome, functions in telomere maintenance. J Biol Chem 2011; 287:196-209. [PMID: 22039056 DOI: 10.1074/jbc.m111.295063] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Telomeres are structures at the ends of chromosomes and are composed of long tracks of short tandem repeat DNA sequences bound by a unique set of proteins (shelterin). Telomeric DNA is believed to form G-quadruplex and D-loop structures, which presents a challenge to the DNA replication and repair machinery. Although the RecQ helicases WRN and BLM are implicated in the resolution of telomeric secondary structures, very little is known about RECQL4, the RecQ helicase mutated in Rothmund-Thomson syndrome (RTS). Here, we report that RTS patient cells have elevated levels of fragile telomeric ends and that RECQL4-depleted human cells accumulate fragile sites, sister chromosome exchanges, and double strand breaks at telomeric sites. Further, RECQL4 localizes to telomeres and associates with shelterin proteins TRF1 and TRF2. Using recombinant proteins we showed that RECQL4 resolves telomeric D-loop structures with the help of shelterin proteins TRF1, TRF2, and POT1. We also found a novel functional synergistic interaction of this protein with WRN during D-loop unwinding. These data implicate RECQL4 in telomere maintenance.
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Affiliation(s)
- Avik K Ghosh
- Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Marie L Rossi
- Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Dharmendra Kumar Singh
- Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Christopher Dunn
- Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Mahesh Ramamoorthy
- Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Yie Liu
- Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224.
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17
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The N-terminal region of RECQL4 lacking the helicase domain is both essential and sufficient for the viability of vertebrate cells. Role of the N-terminal region of RECQL4 in cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:473-9. [PMID: 21256165 DOI: 10.1016/j.bbamcr.2011.01.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 12/02/2010] [Accepted: 01/03/2011] [Indexed: 01/29/2023]
Abstract
Rothmund-Thomson syndrome (RTS) is a rare genetic disorder characterized by premature aging, developmental abnormalities, and a predisposition to cancer. RTS is caused by mutations in the RECQL4 gene, which encodes one of the five human RecQ helicases. To identify the cellular functions of RECQL4, we generated a chicken DT40 cell line in which RECQL4 expression could be turned off by doxycycline (Dox). Upon exposure to Dox, cells stopped growing and underwent apoptosis. The cells could be rescued by expression of the N-terminal region of RECQL4 (amino acids 1-496), which lacks the helicase domain and has sequence similarity to yeast Sld2, which plays an essential function in the initiation of DNA replication in Saccharomyces cerevisiae. Smaller fragments of the N-terminal region of RECQL4 did not rescue the cells from lethality. RECQL4 gene knockout cells complemented with RECQL4 (1-496) showed relatively high sensitivity to DNA damaging agents that induce double strand breaks and cross-links, suggesting that the C-terminal region including the helicase domain of RECQL4 is involved in the repair of certain types of DNA lesions.
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18
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Abstract
Recent work has greatly contributed to the understanding of the biology and biochemistry of RecQ4. It plays an essential non-enzymatic role in the formation of the CMG complex, and thus replication initiation, by means of its Sld2 homologous domain. The helicase domain of RecQ4 has now been demonstrated to possess 3'-5' DNA helicase activity, like the other members of the RecQ family. The biological purpose of this activity is still unclear, but helicase-dead mutants are unable to restore viability in the absence of wildtype RecQ4. This indicates that RecQ4 performs a second role, which requires helicase activity and is implicated in replication and DNA repair. Thus, it is clear that two helicases, RecQ4 and Mcm2-7, are integral to replication. The nature of the simultaneous involvement of these two helicases remains to be determined, and possible models will be proposed.
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Affiliation(s)
- Christopher Capp
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
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19
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Hinz JM. Role of homologous recombination in DNA interstrand crosslink repair. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:582-603. [PMID: 20658649 DOI: 10.1002/em.20577] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Homologous recombination repair (HRR) encompasses mechanisms that employ homologous DNA sequences as templates for repair or tolerance of a wide range of DNA lesions that inhibit DNA replication in S phase. Arguably the most imposing of these DNA lesions is that of the interstrand crosslink (ICL), consisting of a covalently attached chemical bridge between opposing DNA strands. ICL repair requires the coordinated activities of HRR and a number of proteins from other DNA repair and damage response systems, including nucleotide excision repair, base excision repair, mismatch repair, and translesion DNA synthesis (TLS). Interestingly, different organisms favor alternative methods of HRR in the ICL repair process. E. coli perform ICL repair using a homology-driven damage bypass mechanism analogous to daughter strand gap repair. Eukaryotes from yeast to humans initiate ICL repair primarily during DNA replication, relying on HRR activity to restart broken replication forks associated with double-strand break intermediates induced by nucleolytic activities of other excision repair factors. Higher eukaryotes also employ several additional factors, including members of the Fanconi anemia damage-response network, which further promote replication-associated ICL repair through the activation and coordination of various DNA excision repair, TLS, and HRR proteins. This review focuses on the proteins and general mechanisms of HRR associated with ICL repair in different model organisms.
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Affiliation(s)
- John M Hinz
- School of Molecular Biosciences, Washington State University, Pullman, Washington, USA.
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20
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Singh DK, Karmakar P, Aamann M, Schurman SH, May A, Croteau DL, Burks L, Plon SE, Bohr VA. The involvement of human RECQL4 in DNA double-strand break repair. Aging Cell 2010; 9:358-71. [PMID: 20222902 DOI: 10.1111/j.1474-9726.2010.00562.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Rothmund-Thomson syndrome (RTS) is an autosomal recessive hereditary disorder associated with mutation in RECQL4 gene, a member of the human RecQ helicases. The disease is characterized by genomic instability, skeletal abnormalities and predisposition to malignant tumors, especially osteosarcomas. The precise role of RECQL4 in cellular pathways is largely unknown; however, recent evidence suggests its involvement in multiple DNA metabolic pathways. This study investigates the roles of RECQL4 in DNA double-strand break (DSB) repair. The results show that RECQL4-deficient fibroblasts are moderately sensitive to gamma-irradiation and accumulate more gammaH2AX and 53BP1 foci than control fibroblasts. This is suggestive of defects in efficient repair of DSB's in the RECQL4-deficient fibroblasts. Real time imaging of live cells using laser confocal microscopy shows that RECQL4 is recruited early to laser-induced DSBs and remains for a shorter duration than WRN and BLM, indicating its distinct role in repair of DSBs. Endogenous RECQL4 also colocalizes with gammaH2AX at the site of DSBs. The RECQL4 domain responsible for its DNA damage localization has been mapped to the unique N-terminus domain between amino acids 363-492, which shares no homology to recruitment domains of WRN and BLM to the DSBs. Further, the recruitment of RECQL4 to laser-induced DNA damage is independent of functional WRN, BLM or ATM proteins. These results suggest distinct cellular dynamics for RECQL4 protein at the site of laser-induced DSB and that it might play important roles in efficient repair of DSB's.
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Affiliation(s)
- Dharmendra Kumar Singh
- Laboratory of Molecular Gerontology, Biomedical Research Center, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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21
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Abstract
Rothmund-Thomson syndrome (RTS) is a genodermatosis presenting with a characteristic facial rash (poikiloderma) associated with short stature, sparse scalp hair, sparse or absent eyelashes and/or eyebrows, juvenile cataracts, skeletal abnormalities, radial ray defects, premature aging and a predisposition to cancer. The prevalence is unknown but around 300 cases have been reported in the literature so far. The diagnostic hallmark is facial erythema, which spreads to the extremities but spares the trunk, and which manifests itself within the first year and then develops into poikiloderma. Two clinical subforms of RTS have been defined: RTSI characterised by poikiloderma, ectodermal dysplasia and juvenile cataracts, and RTSII characterised by poikiloderma, congenital bone defects and an increased risk of osteosarcoma in childhood and skin cancer later in life. The skeletal abnormalities may be overt (frontal bossing, saddle nose and congenital radial ray defects), and/or subtle (visible only by radiographic analysis). Gastrointestinal, respiratory and haematological signs have been reported in a few patients. RTS is transmitted in an autosomal recessive manner and is genetically heterogeneous: RTSII is caused by homozygous or compound heterozygous mutations in the RECQL4 helicase gene (detected in 60-65% of RTS patients), whereas the aetiology in RTSI remains unknown. Diagnosis is based on clinical findings (primarily on the age of onset, spreading and appearance of the poikiloderma) and molecular analysis for RECQL4 mutations. Missense mutations are rare, while frameshift, nonsense mutations and splice-site mutations prevail. A fully informative test requires transcript analysis not to overlook intronic deletions causing missplicing. The diagnosis of RTS should be considered in all patients with osteosarcoma, particularly if associated with skin changes. The differential diagnosis should include other causes of childhood poikiloderma (including dyskeratosis congenita, Kindler syndrome and Poikiloderma with Neutropaenia), other rare genodermatoses with prominent telangiectasias (including Bloom syndrome, Werner syndrome and Ataxia-telangiectasia) and the allelic disorders, RAPADILINO syndrome and Baller-Gerold syndrome, which also share some clinical features. A few mutations recur in all three RECQL4 diseases. Genetic counselling should be provided for RTS patients and their families, together with a recommendation for cancer surveillance for all patients with RTSII. Patients should be managed by a multidisciplinary team and offered long term follow-up. Treatment includes the use of pulsed dye laser photocoagulation to improve the telangiectatic component of the rash, surgical removal of the cataracts and standard treatment for individuals who develop cancer. Although some clinical signs suggest precocious aging, life expectancy is not impaired in RTS patients if they do not develop cancer. Outcomes in patients with osteosarcoma are similar in RTS and non-RTS patients, with a five-year survival rate of 60-70%. The sensitivity of RTS cells to genotoxic agents exploiting cells with a known RECQL4 status is being elucidated and is aimed at optimizing the chemotherapeutic regimen for osteosarcoma.
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Affiliation(s)
- Lidia Larizza
- Department of Medicine, Surgery and Dentistry, University of Milan, Italy
| | - Gaia Roversi
- Department of Medicine, Surgery and Dentistry, University of Milan, Italy
- National Cancer Institute, Milan, Italy
| | - Ludovica Volpi
- Department of Biology for Medical Sciences, University of Milan, Italy
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22
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Xu Y, Lei Z, Huang H, Dui W, Liang X, Ma J, Jiao R. dRecQ4 is required for DNA synthesis and essential for cell proliferation in Drosophila. PLoS One 2009; 4:e6107. [PMID: 19572017 PMCID: PMC2700968 DOI: 10.1371/journal.pone.0006107] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Accepted: 06/02/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The family of RecQ DNA helicases plays an important role in the maintenance of genomic integrity. Mutations in three of the five known RecQ family members in humans, BLM, WRN and RecQ4, lead to disorders that are characterized by predisposition to cancer and premature aging. METHODOLOGY/PRINCIPAL FINDINGS To address the in vivo functions of Drosophila RecQ4 (dRecQ4), we generated mutant alleles of dRecQ4 using the targeted gene knock-out technique. Our data show that dRecQ4 mutants are homozygous lethal with defects in DNA replication, cell cycle progression and cell proliferation. Two sets of experiments suggest that dRecQ4 also plays a role in DNA double strand break repair. First, mutant animals exhibit sensitivity to gamma irradiation. Second, the efficiency of DsRed reconstitution via single strand annealing repair is significantly reduced in the dRecQ4 mutant animals. Rescue experiments further show that both the N-terminal domain and the helicase domain are essential to dRecQ4 function in vivo. The N-terminal domain is sufficient for the DNA repair function of dRecQ4. CONCLUSIONS/SIGNIFICANCE Together, our results show that dRecQ4 is an essential gene that plays an important role in not only DNA replication but also DNA repair and cell cycle progression in vivo.
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Affiliation(s)
- Yanjuan Xu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - Zhiyong Lei
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China
| | - Hai Huang
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - Wen Dui
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - Xuehong Liang
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China
| | - Jun Ma
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China
- Divisions of Biomedical Informatics and Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, Ohio, United States of America
| | - Renjie Jiao
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, the Chinese Academy of Sciences, Beijing, China
- * E-mail:
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23
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Schurman SH, Hedayati M, Wang Z, Singh DK, Speina E, Zhang Y, Becker K, Macris M, Sung P, Wilson DM, Croteau DL, Bohr VA. Direct and indirect roles of RECQL4 in modulating base excision repair capacity. Hum Mol Genet 2009; 18:3470-83. [PMID: 19567405 DOI: 10.1093/hmg/ddp291] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
RECQL4 is a human RecQ helicase which is mutated in approximately two-thirds of individuals with Rothmund-Thomson syndrome (RTS), a disease characterized at the cellular level by chromosomal instability. BLM and WRN are also human RecQ helicases, which are mutated in Bloom and Werner's syndrome, respectively, and associated with chromosomal instability as well as premature aging. Here we show that primary RTS and RECQL4 siRNA knockdown human fibroblasts accumulate more H(2)O(2)-induced DNA strand breaks than control cells, suggesting that RECQL4 may stimulate repair of H(2)O(2)-induced DNA damage. RTS primary fibroblasts also accumulate more XRCC1 foci than control cells in response to endogenous or induced oxidative stress and have a high basal level of endogenous formamidopyrimidines. In cells treated with H(2)O(2), RECQL4 co-localizes with APE1, and FEN1, key participants in base excision repair. Biochemical experiments indicate that RECQL4 specifically stimulates the apurinic endonuclease activity of APE1, the DNA strand displacement activity of DNA polymerase beta, and incision of a 1- or 10-nucleotide flap DNA substrate by Flap Endonuclease I. Additionally, RTS cells display an upregulation of BER pathway genes and fail to respond like normal cells to oxidative stress. The data herein support a model in which RECQL4 regulates both directly and indirectly base excision repair capacity.
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Affiliation(s)
- Shepherd H Schurman
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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24
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Roles of RECQ helicases in recombination based DNA repair, genomic stability and aging. Biogerontology 2008; 10:235-52. [PMID: 19083132 DOI: 10.1007/s10522-008-9205-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 11/24/2008] [Indexed: 12/28/2022]
Abstract
The maintenance of the stability of genetic material is an essential feature of every living organism. Organisms across all kingdoms have evolved diverse and highly efficient repair mechanisms to protect the genome from deleterious consequences of various genotoxic factors that might tend to destabilize the integrity of the genome in each generation. One such group of proteins that is actively involved in genome surveillance is the RecQ helicase family. These proteins are highly conserved DNA helicases, which have diverse roles in multiple DNA metabolic processes such as DNA replication, recombination and DNA repair. In humans, five RecQ helicases have been identified and three of them namely, WRN, BLM and RecQL4 have been linked to genetic diseases characterized by genome instability, premature aging and cancer predisposition. This helicase family plays important roles in various DNA repair pathways including protecting the genome from illegitimate recombination during chromosome segregation in mitosis and assuring genome stability. This review mainly focuses on various roles of human RecQ helicases in the process of recombination-based DNA repair to maintain genome stability and physiological consequences of their defects in the development of cancer and premature aging.
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25
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Abstract
Mutations in the RECQL4 gene can lead to three clinical phenotypes with overlapping features. All these syndromes, Rothmund-Thomson (RTS), RAPADILINO and Baller-Gerold (BGS), are characterized by growth retardation and radial defects, but RAPADILINO syndrome lacks the main dermal manifestation, poikiloderma that is a hallmark feature in both RTS and BGS. It has been previously shown that RTS patients with RECQL4 mutations are at increased risk of osteosarcoma, but the precise incidence of cancer in RAPADILINO and BGS has not been determined. Here, we report that RAPADILINO patients identified as carriers of the c.1390+2delT mutation (p.Ala420_Ala463del) are at increased risk to develop lymphoma or osteosarcoma (6 out of 15 patients). We also summarize all the published RECQL4 mutations and their associated cancer cases and provide an update of 14 novel RECQL4 mutations with accompanying clinical data.
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