WRN is required for ATM activation and the S-phase checkpoint in response to interstrand cross-link-induced DNA double-strand breaks.
Werner syndrome (WS) is a human genetic disorder characterized by extensive clinical features of premature aging. Ataxia-telengiectasia (A-T) is a multisystem human genomic instability syndrome that includes premature aging in some of the patients. WRN and ATM, the proteins defective in WS and A-T, respectively, play significant roles in the maintenance of genomic stability and are involved in several DNA metabolic pathways. A role for WRN in DNA repair has been proposed; however, this study provides evidence that WRN is also involved in ATM pathway activation and in a S-phase checkpoint in cells exposed to DNA interstrand cross-link-induced double-strand breaks. Depletion of WRN in such cells by RNA interference results in an intra-S checkpoint defect, and interferes with activation of ATM as well as downstream phosphorylation of ATM target proteins. Treatment of cells under replication stress with the ATM kinase inhibitor KU 55933 results in a S-phase checkpoint defect similar to that observed in WRN shRNA cells. Moreover, gamma H2AX levels are higher in WRN shRNA cells than in control cells 6 and 16 h after exposure to psoralen DNA cross-links. These results suggest that WRN and ATM participate in a replication checkpoint response, in which WRN facilitates ATM activation in cells with psoralen DNA cross-link-induced collapsed replication forks.
Cheng
Wen-Hsing
WH
Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
Muftic
Diana
D
Muftuoglu
Meltem
M
Dawut
Lale
L
Morris
Christa
C
Helleday
Thomas
T
Shiloh
Yosef
Y
Bohr
Vilhelm A
VA
D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005090:Exodeoxyribonucleases / Q000378:metabolism* / Q000502:physiology*; D005363:Ficusin / Q000494:pharmacology; D006801:Humans; D008856:Microscopy, Fluorescence; D009025:Morpholines / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011753:Pyrones / Q000494:pharmacology*; D034622:RNA Interference; D053484:RecQ Helicases / Q000378:metabolism* / Q000502:physiology*; D016196:S Phase; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D000071657:Werner Syndrome Helicase
C495818:2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one; D018797:Cell Cycle Proteins; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D009025:Morpholines; D011753:Pyrones; D025521:Tumor Suppressor Proteins; D004247:DNA; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D005090:Exodeoxyribonucleases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase; D005363:Ficusin