title: Regulation of the antioncogenic Chk2 kinase by the oncogenic Wip1 phosphatase.
abstract: The antioncogenic Chk2 kinase plays a crucial role in DNA damage-induced cell-cycle checkpoint regulation. Here we show that Chk2 associates with the oncogenic protein Wip1 (wild-type p53-inducible phosphatase 1) (PPM1D), a p53-inducible protein phosphatase. Phosphorylation of Chk2 at threonine68 (Thr68), a critical event for Chk2 activation, which is normally induced by DNA damage or overexpression of Chk2, is inhibited by expression of wild-type (WT), but not a phosphatase-deficient mutant (D314A) of Wip1 in cultured cells. Furthermore, an in vitro phosphatase assay revealed that Wip1 (WT), but not Wip1 (D314A), dephosphorylates Thr68 on phosphorylated Chk2 in vitro, resulting in the inhibition of Chk2 kinase activity toward glutathione S-transferase-Cdc25C. Moreover, inhibition of Wip1 expression by RNA interference results in abnormally sustained Thr68 phosphorylation of Chk2 and increased susceptibility of cells in response to DNA damage, indicating that Wip1 acts as a negative regulator of Chk2 in response to DNA damage.
authors.affiliation: 1Department of Genome Sciences, Faculty of Medical Sciences, Graduate School of Medicine, Kobe University, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Fujimoto
authors.forename: N
authors.initials: N
authors.lastname: Onishi
authors.forename: N
authors.initials: N
authors.lastname: Kato
authors.forename: M
authors.initials: M
authors.lastname: Takekawa
authors.forename: X Z
authors.initials: XZ
authors.lastname: Xu
authors.forename: A
authors.initials: A
authors.lastname: Kosugi
authors.forename: T
authors.initials: T
authors.lastname: Kondo
authors.forename: M
authors.initials: M
authors.lastname: Imamura
authors.forename: I
authors.initials: I
authors.lastname: Oishi
authors.forename: A
authors.initials: A
authors.lastname: Yoda
authors.forename: Y
authors.initials: Y
authors.lastname: Minami
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D045325:HCT116 Cells; D006801:Humans; D015151:Immunoblotting; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D054645:Protein Phosphatase 1; D000071636:Protein Phosphatase 2C; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000596:Amino Acids; D018797:Cell Cycle Proteins; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D013912:Threonine; D012694:Serine; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases; C000607458:PPM1D protein, human; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D000071636:Protein Phosphatase 2C