title: Nuclear pp64 is phosphorylated in both serine/threonine and tyrosine through complex pathways regulated by 12-O-tetradecanoylphorbol-13-acetate and platelet-derived growth factor.
abstract: Platelet-derived growth factor (PDGF) induces the time and dose dependent serine/threonine phosphorylation of pp64, a nuclear protein in normal rat kidney (NRK) cells. pp64 is phosphorylated additionally on tyrosine in SSV-transformed NRK cells. To further characterize the regulation of phosphorylation of pp64, other mitogens and inhibitors were studied. 12-O-tetradecanoylphorbol-13-acetate (TPA) but not epidermal growth factor (EGF) or insulin induced the phosphorylation of nuclear pp64. Addition of the inhibitor H7 to TPA-treated NRK cells resulted in a striking further increase in phosphorylation of pp64 and, to a lesser extent, in NRK cells treated with PDGF and H7. When cells were treated with PDGF and H7, pp64 was recognized by anti-phosphotyrosine antisera. The increased phosphorylation induced by H7 was inhibited when forskolin was included. This loss of phosphorylation in pp64 with forskolin treatment paralleled a loss of immunoreactivity of pp64 to anti-phosphosphotyrosine. Complex and independent pathways thus appear to signal the growth factor dependent nuclear phosphorylation of pp64, involving phosphorylations both on serine/threonine and on tyrosine.
authors.affiliation: Department of Medicine, Jewish Hospital at Washington University Medical Center, St. Louis, Missouri 63110.
authors.forename: L K
authors.initials: LK
authors.lastname: Shawver
authors.forename: T F
authors.initials: TF
authors.lastname: Deuel
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D002460:Cell Line; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc; D012694:Serine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013912:Threonine; D014443:Tyrosine
chemical_list: D007546:Isoquinolines; D009687:Nuclear Proteins; D010879:Piperazines; D010982:Platelet-Derived Growth Factor; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D013912:Threonine; D014443:Tyrosine; D012694:Serine; D004815:Epidermal Growth Factor; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D013755:Tetradecanoylphorbol Acetate; D004121:Dimethyl Sulfoxide