title: Identification of beta-catenin as a novel substrate of Polo-like kinase 1.
abstract: Polo-like kinase 1 (Plk1) is a serine/threonine kinase that plays an important role in M phase progression by regulating various downstream substrates via phosphorylation. Here, we identified beta-catenin as a novel substrate of Plk1 and determined that Ser-718 is a phosphorylation site for Plk1 by using a phospho-specific antibody that cross-reacts with Plk1-dependent phosphorylation sites. Ser-718 of beta-catenin was directly phosphorylated by recombinant Plk1 in vitro, with the phosphorylation signal in cells increasing with overexpression of Plk1 and decreasing when endogenous Plk1 was depleted by small interfering RNA. The phosphorylation at Ser-718 was correlated with the cell cycle-dependent expression of Plk1 which reached a maximum in M phase. We also confirmed that there is a physical interaction between beta-catenin and Plk1 using coimmunoprecipitation and a GST pull-down assay. These results demonstrate that beta-catenin is a physiological substrate of Plk1 in cells, which may provide a novel insight into the role of beta-catenin in M phase.
authors.affiliation: Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd., Tsukuba, Ibaraki, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Arai
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Haze
authors.forename: Yuko
authors.initials: Y
authors.lastname: Iimura-Morita
authors.forename: Takumitsu
authors.initials: T
authors.lastname: Machida
authors.forename: Masato
authors.initials: M
authors.lastname: Iida
authors.forename: Kenji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Hideya
authors.initials: H
authors.lastname: Komatani
mesh_terms: D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002455:Cell Division; D002460:Cell Line; D015870:Gene Expression; D006801:Humans; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity; D051176:beta Catenin / Q000378:metabolism* / Q000502:physiology; D000097869:Polo-Like Kinase 1
chemical_list: D018797:Cell Cycle Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D012694:Serine; D051176:beta Catenin; D000097869:Polo-Like Kinase 1