title: The DNA damage effector Chk1 kinase regulates Cdc14B nucleolar shuttling during cell cycle progression.
abstract: Chk1 is a critical effector of DNA damage checkpoints necessary for the maintenance of chromosome integrity during cell cycle progression. Here we report, that Chk1 co-localized with the nucleolar marker, fibrillarin in response to radiation-induced DNA damage in human cells. Interestingly, in vitro studies using GST pull down assays identified the dual-specificity serine/threonine nucleolar phosphatase Cdc14B as a Chk1 substrate. Furthermore, Chk1, but not a kinase-dead Chk1 control, was shown to phosphorylate Cdc14B using an in vitro kinase assay. Co-immunoprecipitation experiments using exogenous Cdc14B transfected into human cells confirmed the interaction of Cdc14B and Chk1 during cell cycle. In addition, reduction of Chk1 levels via siRNA or UCN-01 treatment demonstrated that Chk1 activation following DNA damage was required for Cdc14B export from the nucleolus. These studies have revealed a novel interplay between Chk1 kinase and Cdc14B phosphatase involving radiation-induced nucleolar shuttling to facilitate error-free cell cycle progression and prevent genomic instability.
authors.affiliation: Department of Molecular and Cell Biology, Baylor College of Medicine, Houston, TX USA.
authors.forename: Sirisha
authors.initials: S
authors.lastname: Peddibhotla
authors.forename: Zhubo
authors.initials: Z
authors.lastname: Wei
authors.forename: Rao
authors.initials: R
authors.lastname: Papineni
authors.forename: Micheal H
authors.initials: MH
authors.lastname: Lam
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Rosen
authors.forename: Pumin
authors.initials: P
authors.lastname: Zhang
mesh_terms: D015153:Blotting, Western; D002453:Cell Cycle; D002460:Cell Line; D002466:Cell Nucleolus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D000071877:Checkpoint Kinase 1; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D002877:Chromosomes, Human / Q000235:genetics / Q000502:physiology; D004249:DNA Damage; D054637:Dual-Specificity Phosphatases / Q000235:genetics / Q000378:metabolism*; D042822:Genomic Instability; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D019311:Staurosporine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D034741:RNA, Small Interfering; C047458:fibrillarin; C054852:7-hydroxystaurosporine; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; C474200:CDC14B protein, human; D054637:Dual-Specificity Phosphatases; D019311:Staurosporine