Werner syndrome protein is regulated and phosphorylated by DNA-dependent protein kinase.
DNA double-strand breaks (DSBs) are a highly mutagenic and potentially lethal damage that occurs in all organisms. Mammalian cells repair DSBs by homologous recombination and non-homologous end joining, the latter requiring DNA-dependent protein kinase (DNA-PK). Werner syndrome is a disorder characterized by genomic instability, aging pathologies and defective WRN, a RecQ-like helicase with exonuclease activity. We show that WRN interacts directly with the catalytic subunit of DNA-PK (DNA-PK(CS)), which inhibits both the helicase and exonuclease activities of WRN. In addition we show that WRN forms a stable complex on DNA with DNA-PK(CS) and the DNA binding subunit Ku. This assembly reverses WRN enzymatic inhibition. Finally, we show that WRN is phosphorylated in vitro by DNA-PK and requires DNA-PK for phosphorylation in vivo, and that cells deficient in WRN are mildly sensitive to ionizing radiation. These data suggest that DNA-PK and WRN may function together in DNA metabolism and implicate WRN function in non-homologous end joining.
Yannone
S M
SM
Life Sciences Division, Department of Molecular and Cellular Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Roy
S
S
Chan
D W
DW
Murphy
M B
MB
Huang
S
S
Campisi
J
J
Chen
D J
DJ
D000730:Androstadienes / Q000494:pharmacology; D001483:Base Sequence; D004265:DNA Helicases / Q000378:metabolism*; D017931:DNA Primers; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005090:Exodeoxyribonucleases; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053484:RecQ Helicases; D014898:Werner Syndrome / Q000378:metabolism*; D000071657:Werner Syndrome Helicase; D000077191:Wortmannin
D000730:Androstadienes; D017931:DNA Primers; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases; D005090:Exodeoxyribonucleases; D004265:DNA Helicases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase; D000077191:Wortmannin