Shawver L K, Deuel T F
Department of Medicine, Jewish Hospital at Washington University Medical Center, St. Louis, Missouri 63110.
Biochem Biophys Res Commun. 1990 Mar 30;167(3):918-26. doi: 10.1016/0006-291x(90)90611-p.
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.
血小板衍生生长因子（PDGF）可诱导正常大鼠肾（NRK）细胞中的一种核蛋白pp64发生时间和剂量依赖性的丝氨酸/苏氨酸磷酸化。在猿猴肉瘤病毒（SSV）转化的NRK细胞中，pp64还会在酪氨酸位点发生磷酸化。为了进一步表征pp64磷酸化的调控机制，研究了其他促有丝分裂原和抑制剂。12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）可诱导核pp64的磷酸化，而表皮生长因子（EGF）或胰岛素则不能。在TPA处理的NRK细胞中加入抑制剂H7，导致pp64的磷酸化显著进一步增加，在PDGF和H7处理的NRK细胞中增加程度较小。当细胞用PDGF和H7处理时，pp64可被抗磷酸酪氨酸抗血清识别。当加入福斯高林时，H7诱导的磷酸化增加受到抑制。福斯高林处理导致pp64磷酸化的丧失与pp64对抗磷酸酪氨酸的免疫反应性丧失平行。因此，复杂且独立的信号通路似乎介导了pp64的生长因子依赖性核磷酸化，涉及丝氨酸/苏氨酸和酪氨酸的磷酸化。
