title: Protein phosphatase 1alpha associates with protein tyrosine phosphatase-PEST inducing dephosphorylation of phospho-serine 39.
abstract: Protein tyrosine phosphatase (PTP)-PEST is expressed in a wide variety of several cell types and is an efficient regulator of cell adhesion, spreading and migration. PTP-PEST-associating molecules are important in elucidating the function of PTP-PEST. Herein, we have identified protein phosphatase 1alpha (PP1alpha) as a novel PTP-PEST binding protein, and then we aimed to determine how PP1alpha contributes to the phosphorylation at Ser39 of PTP-PEST, whose phosphorylation suppresses PTP-PEST enzymatic activity. The HEK 293 cells overexpressing exogenous PTP-PEST were stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) and the phosphorylation of PTP-PEST at Ser39 was evaluated using an anti-phospho-Ser39 PTP-PEST specific antibody (anti-pS39-PEST Ab). It was demonstrated that the phosphorylation at Ser39 detected by anti-pS39-PEST Ab was dependent on TPA treatment and a significant inverse correlation between the PTP activity of PTP-PEST and anti-pS39-PEST Ab-immunoreactive band intensity. The phosphorylation of Ser39 was suppressed by co-transfection of a plasmid encoding wild-type PP1alpha, but not by that of the dominant-negative PP1alpha mutant. Furthermore, TPA-induced phosphorylation could take place in PTP-PEST catalytic domain, but the phosphorylation of PTP-PEST catalytic domain could not be abrogated by co-transfection of a plasmid expressing wild-type PP1alpha. In conclusion, PP1alpha associates with the non-catalytic domain of PTP-PEST and regulates PTP activity via dephosphorylation of phospho-Ser39.
authors.affiliation: Department of Life Science, Rikkyo (St Paul's) University, Nishi-ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Nakamura
authors.forename: Helen E F
authors.initials: HE
authors.lastname: Palmer
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ozawa
authors.forename: Keisuke
authors.initials: K
authors.lastname: Mashima
mesh_terms: D045163:Antibodies, Phospho-Specific; D015153:Blotting, Western; D020134:Catalytic Domain; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006801:Humans; D050505:Mutant Proteins / Q000096:biosynthesis / Q000235:genetics; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D054645:Protein Phosphatase 1 / Q000235:genetics / Q000378:metabolism*; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D045163:Antibodies, Phospho-Specific; D050505:Mutant Proteins; D011993:Recombinant Fusion Proteins; D010768:Phosphoserine; D054645:Protein Phosphatase 1; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D013755:Tetradecanoylphorbol Acetate