title: Dyskeratosis congenita and the DNA damage response.
abstract: Dyskeratosis congenita (DC) is a heterogeneous bone marrow failure disorder with known mutations in components of telomerase and telomere shelterin. Recent work in a mouse model with a dyskerin mutation has implicated an increased DNA damage response as part of the cellular pathology, while mouse models with Terc and Tert mutations displayed a normal response. To clarify how these contradictory results might apply to DC pathology in humans, we studied the cellular phenotype in primary cells from DC patients of several genetic subtypes, focussing on T lymphocytes to remain close to the haematopoietic system. We observed novel cell cycle abnormalities in conjunction with impaired growth and an increase in apoptosis. Using flow cytometry and confocal microscopy we examined induction of the DNA damage proteins γ-H2AX and 53BP1 and the cell cycle protein TP53 (p53). We found an increase in damage foci at telomeres in lymphocytes and an increase in the basal level of DNA damage in fibroblasts, but crucially no increased response to DNA damaging agents in either cell type. As the response to induced DNA damage was normal and levels of global DNA damage were inconsistent between cell types, DNA damage may contribute differently to the pathology in different tissues.
authors.affiliation: Centre for Paediatrics, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London, UK. m.j.kirwan@qmul.ac.uk
authors.forename: Michael
authors.initials: M
authors.lastname: Kirwan
authors.forename: Richard
authors.initials: R
authors.lastname: Beswick
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Walne
authors.forename: Upal
authors.initials: U
authors.lastname: Hossain
authors.forename: Colin
authors.initials: C
authors.lastname: Casimir
authors.forename: Tom
authors.initials: T
authors.lastname: Vulliamy
authors.forename: Inderjeet
authors.initials: I
authors.lastname: Dokal
mesh_terms: D000293:Adolescent; D000328:Adult; D017209:Apoptosis / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D002675:Child, Preschool; D004249:DNA Damage; D019871:Dyskeratosis Congenita / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D013601:T-Lymphocytes / Q000378:metabolism / Q000473:pathology; D016615:Telomere / Q000235:genetics; D046509:Tissue Culture Techniques; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D000071857:Tumor Suppressor p53-Binding Protein 1; D015854:Up-Regulation / Q000235:genetics; D055815:Young Adult
chemical_list: C468783:H2AX protein, human; D006657:Histones; D047908:Intracellular Signaling Peptides and Proteins; C498301:TP53BP1 protein, human; D016159:Tumor Suppressor Protein p53; D000071857:Tumor Suppressor p53-Binding Protein 1