The Caenorhabditis elegans Werner Syndrome Protein Functions Upstream of ATR and ATM in Response to DNA Replication Inhibition and Double-Strand DNA Breaks |
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Authors: | Se-Jin Lee Anton Gartner Moonjung Hyun Byungchan Ahn Hyeon-Sook Koo |
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Affiliation: | 1.Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea;2.Wellcome Trust Centre for Gene Regulation and Expression, School of Life Sciences, The University of Dundee, Dundee, United Kingdom;3.Department of Life Sciences, University of Ulsan, Ulsan, Korea;The University of North Carolina at Chapel Hill, United States of America |
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Abstract: | WRN-1 is the Caenorhabditis elegans homolog of the human Werner syndrome protein, a RecQ helicase, mutations of which are associated with premature aging and increased genome instability. Relatively little is known as to how WRN-1 functions in DNA repair and DNA damage signaling. Here, we take advantage of the genetic and cytological approaches in C. elegans to dissect the epistatic relationship of WRN-1 in various DNA damage checkpoint pathways. We found that WRN-1 is required for CHK1 phosphorylation induced by DNA replication inhibition, but not by UV radiation. Furthermore, WRN-1 influences the RPA-1 focus formation, suggesting that WRN-1 functions in the same step or upstream of RPA-1 in the DNA replication checkpoint pathway. In response to ionizing radiation, RPA-1 focus formation and nuclear localization of ATM depend on WRN-1 and MRE-11. We conclude that C. elegans WRN-1 participates in the initial stages of checkpoint activation induced by DNA replication inhibition and ionizing radiation. These functions of WRN-1 in upstream DNA damage signaling are likely to be conserved, but might be cryptic in human systems due to functional redundancy. |
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