title: DNA-PK-dependent RPA2 hyperphosphorylation facilitates DNA repair and suppresses sister chromatid exchange.
abstract: Hyperphosphorylation of RPA2 at serine 4 and serine 8 (S4, S8) has been used as a marker for activation of the DNA damage response. What types of DNA lesions cause RPA2 hyperphosphorylation, which kinase(s) are responsible for them, and what is the biological outcome of these phosphorylations, however, have not been fully investigated. In this study we demonstrate that RPA2 hyperphosphorylation occurs primarily in response to genotoxic stresses that cause high levels of DNA double-strand breaks (DSBs) and that the DNA-dependent protein kinase complex (DNA-PK) is responsible for the modifications in vivo. Alteration of S4, S8 of RPA2 to alanines, which prevent phosphorylations at these sites, caused increased mitotic entry with concomitant increases in RAD51 foci and homologous recombination. Taken together, our results demonstrate that RPA2 hyperphosphorylation by DNA-PK in response to DSBs blocks unscheduled homologous recombination and delays mitotic entry. This pathway thus permits cells to repair DNA damage properly and increase cell viability.
authors: Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Hungjiun
authors: H
authors: Liaw
authors: Deokjae
authors: D
authors: Lee
authors: Kyungjae
authors: K
authors: Myung
mesh_terms: D015112:4-Nitroquinoline-1-oxide / Q000494:pharmacology; D002460:Cell Line; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D004261:DNA Replication / Q000187:drug effects; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D057809:HEK293 Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D008938:Mitosis / Q000187:drug effects / Q000528:radiation effects; D050505:Mutant Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D051135:Rad51 Recombinase / Q000378:metabolism; D051716:Replication Protein A / Q000378:metabolism*; D012854:Sister Chromatid Exchange / Q000187:drug effects / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: C468783:H2AX protein, human; D006657:Histones; D050505:Mutant Proteins; D051716:Replication Protein A; D015112:4-Nitroquinoline-1-oxide; D051747:DNA-Activated Protein Kinase; D018844:Cyclin-Dependent Kinases; D051135:Rad51 Recombinase; C516794:RPA2 protein, human