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.
Bibliographical noteFunding Information:
We thank Dr. Yuji Kohara (National Institute of Genetics, Japan) for the EST clones. C. elegans N2, wrn-1(gk99), and atm-1(gk186) strains were obtained from the C. elegans Genetics Center (St. Paul, MN), which is supported by the National Center for Research Resources. The wrn-1(tm764) strain was kindly provided by the National Center for Bioresource Project (Japan). The monoclonal antibody against α-tubulin developed by Frankel J. and Nielsen, E.M., was obtained from the Developmental Studies Hybridoma Bank developed under the auspices of the NICHD and maintained by The University of Iowa, Department of Biological Sciences, Iowa City, IA 52242.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Molecular Biology
- Cancer Research