title: Protein phosphatase 5 regulates the function of 53BP1 after neocarzinostatin-induced DNA damage.
abstract: 53BP1 (p53-binding protein 1) is a conserved nuclear protein that is phosphorylated in response to DNA damage and rapidly recruited to the site of DNA double strand breaks, demonstrating its role in the early events to DNA damage and repair of damaged DNA. In this study, we used the yeast two-hybrid system to identify proteins that interact with 53BP1. Identification and characterization of 53BP1 protein interactions may help to further elucidate the function and regulation of 53BP1. We identified protein phosphatase 5 (PP5), a serine/threonine phosphatase that has been implicated in multiple cellular function, as a 53BP1-binding protein. This interaction further confirmed that 53BP1 interacts with PP5 in PP5-overexpressing U2OS cells, after radiomimetic agent neocarzinostatin (NCS) treatment. 53BP1 dephosphorylation at Ser-25 and Ser-1778 was accelerated in PP5-overexpressing U2OS cells following NCS treatment, and its dephosphorylation was correlated with reduced phospho-53BP1 foci formation. In contrast, the overexpression of PP5 had no effect on NCS-activated BRCA1-Ser-1524 phosphorylation. Additionally, PP5 down-regulation inhibited the dephosphorylation of 53BP1 on Ser-1778 and the disappearance of phospho-53BP1 foci following NCS treatment. Moreover, non-homologous end-joining activity was reduced in PP5-overexpressing U2OS cells. These findings indicate that PP5 plays an important role in the regulation of 53BP1 phosphorylation and activity in vivo.
authors.affiliation: Departments of Pharmacology, Bio-materials, Orthopedic Surgery, and Anatomy, Chosun University, 375 Seosuk-dong, Gwangju 501-759, Korea.
authors.forename: Yoonsung
authors.initials: Y
authors.lastname: Kang
authors.forename: Jung-Hee
authors.initials: JH
authors.lastname: Lee
authors.forename: Nguyen Ngoc
authors.initials: NN
authors.lastname: Hoan
authors.forename: Hong-Moon
authors.initials: HM
authors.lastname: Sohn
authors.forename: In-Youb
authors.initials: IY
authors.lastname: Chang
authors.forename: Ho Jin
authors.initials: HJ
authors.lastname: You
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D015536:Down-Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence / Q000379:methods; D009687:Nuclear Proteins / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D013997:Time Factors; D000071857:Tumor Suppressor p53-Binding Protein 1; D009353:Zinostatin / Q000494:pharmacology
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1; D004247:DNA; D009353:Zinostatin; D010749:Phosphoprotein Phosphatases; C089641:protein phosphatase 5