INHIBITION OF VASCULAR CELL PROLIFERATION BY CYCLIC GMP

描述：（改编自应用程序）：该项目的长期目标 项目是研究cGMP升高剂（cGMP） 激动剂）抑制主动脉平滑肌的原代培养物中的DNA合成 从新生大鼠中分离的细胞。 初步实验表明， cGMP激动剂抑制基础和生长因子模拟的DNA合成。 此外，这些激动剂导致磷酸酪氨酸磷酸化减少， 在选定的蛋白质中，表明一种或多种蛋白质酪氨酸 磷酸酶 过氧钒酸盐，一种有效的选择性PTPases抑制剂， 逆转抗有丝分裂作用以及蛋白磷酸酪氨酸 cGMP激动剂诱导的去磷酸化，从而将生物化学 磷酸酪氨酸去磷酸化事件至生理终点 减少DNA合成。 自上次报告以来最近完成的其他工作 提交的材料表明，cGMP激动剂和其他药物， 钙，诱导磷酸酪氨酸去磷酸化和增加PTK 在细胞匀浆或胞质组分中的活性。 一个这样的代理人， 硝苯地平也抑制DNA合成，提供了进一步的证据， 生化和生理终点。 白屈菜红碱，选择性 蛋白激酶C抑制剂，也诱导蛋白磷酸酪氨酸 去磷酸化，表明PKC参与这些事件。 总的来说，这些结果表明cGMP的抗有丝分裂作用 激动剂和钙离子进入阻滞剂可通过降低 胞浆钙离子浓度降低，随后PKC活性降低， 激活一种或多种PTPases。 本提案的目的是 研究这些效应背后的机制。 为此，PI 建议测试以下假设：环GMP激动剂和 其他降低细胞质钙水平的药物激活一种特异性的 钙通过蛋白激酶C抑制蛋白激酶活性？ 激活该PTOTH， 导致特定蛋白质的磷酸酪氨酸去磷酸化。 测试 这一假说的目的是：1）确定是否抑制PKC 模拟和下调或激活PKC阻断或减弱 cGMP激动剂和其它降低钙作用剂对蛋白质的影响 磷酸酪氨酸去磷酸化; 2）鉴定蛋白质底物 其响应cGMP激动剂而被磷酸酪氨酸去磷酸化， 其他降低钙的药物;以及3）鉴定 由cGMP激动剂和其他降低钙的药物激活。

DESCRIPTION: (Adapted from the application): The long-term goal of this project is to study the mechanisms by which cGMP-elevating agents (cGMP agonists) inhibit DNA synthesis in primary cultures of aortic smooth muscle cells isolated from newborn rats. Preliminary experiments indicate that cGMP agonists inhibit both basal and growth factor simulated DNA synthesis. Moreover, these agonists cause reduction in phosphotyrosine phosphorylation in selected proteins, suggesting activation of one or more protein tyrosine phosphatases. Peroxovanadate, a potent and selective inhibitor of PTPases, reverses the antimitogenic effect as well as the protein phosphotyrosine dephosphorylation induced by cGMP agonists, thus linking the biochemical event of phosphotyrosine dephosphorylation to the physiological endpoint of decreased DNA synthesis. Additional recent work performed since the last submission indicates that cGMP agonists, and other agents which decrease calcium, induce phosphotyrosine dephosphorylation and increase PTPase activity in cell homogenates or cytosolic fractions. One such agent, nifedipine, also inhibits DNA synthesis, providing further evidence linking the biochemical and physiological endpoints. Chelerythrine, a selective inhibitor of protein kinase C, also induces protein phosphotyrosine dephosphorylation, suggesting the involvement of PKC in these events. Collectively, these results suggest the antimitogenic effect of cGMP agonists and calcium entry blockers may be mediated by a decreased cytoplasmic calcium followed by decreased PKC activity and increased activation of one or more PTPases. The purpose of the current proposal is to investigate the mechanism underlying these effects. To this end, the PI proposes to test the following hypothesis: Can cyclic GMP agonists and other agents that decrease cytoplasmic calcium levels activate a specific PTPase that is inhibited by calcium via PKC? Activation of this PTPase then causes the phosphotyrosine dephosphorylation of specific proteins. To test this hypothesis the aims are: 1) to determine whether inhibition of PKC mimics and downregulation or activation of PKC blocks or attenuates the effect of cGMP agonists and other agents that decrease calcium on protein phosphotyrosine dephosphorylation; 2) to identify the protein substrates that are phosphotyrosine dephosphorylated in response to cGMP agonists and other agents that reduce calcium; and 3) to identify a PTPase that is activated by cGMP agonists and other agents that decrease calcium.