title: Nek1 kinase functions in DNA damage response and checkpoint control through a pathway independent of ATM and ATR.
abstract: Never-in-mitosis A related protein kinase 1 (Nek1) is involved early in a DNA damage sensing/repair pathway. We have previously shown that cells without functional Nek1 fail to activate the more distal kinases Chk1 and Chk2 and fail to arrest properly at G1/S or M-phase checkpoints in response to DNA damage. As a consequence, foci of damaged DNA in Nek1 null cells persist long after the instigating insult, and Nek1 null cells develop unstable chromosomes at a rate much higher than identically cultured wild type cells. Here we show that Nek1 functions independently of canonical DNA damage responses requiring the PI3 kinase-like proteins ATM and ATR. Chemical inhibitors of ATM/ATR or mutation of the genes that encode them fail to alter the kinase activity of Nek1 or its localization to nuclear foci of DNA damage. Moreover ATM and ATR activities, including the localization of the proteins to DNA damage sites and phosphorylation of early DNA damage response substrates, are intact in Nek1 -/- murine cells and in human cells with Nek1 expression silenced by siRNA. Our results demonstrate that Nek1 is important for proper checkpoint control and characterize for the first time a DNA damage response that does not directly involve one of the known upstream mediator kinases, ATM or ATR.
authors.affiliation: Department of Medicine, University of California at Irvine, Irvine, CA USA. yumayc@uci.edu
authors.forename: Yumay
authors.initials: Y
authors.lastname: Chen
authors.forename: Chi-Fen
authors.initials: CF
authors.lastname: Chen
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Riley
authors.forename: Phang-Lang
authors.initials: PL
authors.lastname: Chen
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000276:immunology; D064007:Ataxia Telangiectasia Mutated Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D002867:Chromones / Q000494:pharmacology; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004260:DNA Repair; D006801:Humans; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D000072380:NIMA-Related Kinase 1; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D014157:Transcription Factors; D000077191:Wortmannin
chemical_list: C522841:ATMIN protein, human; D000730:Androstadienes; D000906:Antibodies; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002867:Chromones; D009025:Morpholines; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse; C578633:Chek2 protein, mouse; C000606914:NEK1 protein, human; D000072380:NIMA-Related Kinase 1; C000606920:Nek1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D000077191:Wortmannin