Replication protein A is required for etoposide-induced assembly of MRE11/RAD50/NBS1 complex repair foci.
The presence of DNA damage activates a specific response cascade culminating in DNA repair activity and cell cycle checkpoints. Although the type of lesion dictates what proteins are involved in the response, replication protein A (RPA) and the Mre11/ Rad50/Nbs1 complex (MRN) respond to most types of lesions. To examine the relationship of RPA and the MRN complex in DNA damage responses, we used siRNA-mediated protein depletion of RPA-p70 and Mre11. Depletion of RPA-p70 decreased the ability of cells to form phospho-Nbs1 foci and increased levels of DNA double-strand breaks (DSBs) following treatment with etoposide (ETOP). In contrast, depletion of Mre11 led to increased levels of RPA-p34 foci formation, but abrogated phospho-RPA-p34 foci formation. These data support a role for RPA as an initial signal/sensor for DNA damage that facilitates recruitment of MRN and ATM/ATR to sites of damage, where they then work together to fully activate the DNA damage response.
Robison
Jacob G
JG
Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Bissler
John J
JJ
Dixon
Kathleen
K
D017766:Acid Anhydride Hydrolases; D018797:Cell Cycle Proteins / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005047:Etoposide / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D000076228:MRE11 Homologue Protein; D009687:Nuclear Proteins / Q000378:metabolism*; D051716:Replication Protein A / Q000378:metabolism*
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; C112156:NBN protein, human; D009687:Nuclear Proteins; C497167:RPA1 protein, human; D051716:Replication Protein A; D005047:Etoposide; D000076228:MRE11 Homologue Protein; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D045643:DNA Repair Enzymes