SIGNAL TRANSDUCTION BY LYSOPHOSPHATIDIC ACID

溶血磷脂酸的信号转导

• 批准号: 6489133
• 负责人: JIE WU
• 金额: $ 10.46万
• 依托单位: UNIVERSITY OF SOUTH FLORIDA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2003-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6489133
• 关键词: biological signal transduction; calcium; cell line; enzyme activity; enzyme induction /repression; enzyme inhibitors; epidermal growth factor; free radical oxygen; growth factor receptors; lysophospholipids; phosphatidate; protein tyrosine kinase; site directed mutagenesis

Lysophosphatidic acid (LPA) is a major mitogen in serum that regulates an array of cellular processes related to pathogenesis of cancer and other human diseases. Despite the central role of LPA in controlling cell growth and other cellular activities, very little is understood about the signaling mechanisms of LPA. While protein tyrosine phosphorylation has been recognized as an important signaling mechanism of LPA and other agonists of G protein-coupled receptors, it remains largely unknown how activation of G-proteins leads to tyrosine phosphorylation. To address this important question, LPA-induced tyrosine phosphorylation of the epidermal growth factor receptor (EGFR) will be studied. Based on our preliminary observations and increasing evidence of redox-regulation in cell signaling, it is postulated that LPA transactivates the EGFR by decreasing EGF receptor phosphatase activity through a mechanism mediated by calcium and reactive oxygen species (ROS). Three specific aims are proposed to critically evaluate key aspects of this hypothesis. In Specific Aim I, the requirement for intrinsic EGFR tyrosine kinase activity will be assessed using kinase- defective EGFR and new specific inhibitors for the EGFR. Effects of decreasing protein tyrosine phosphatase activity toward EGFR will also be examined. Alternatively, a novel sensitive approach is proposed to determine whether LPA activates the EGFR kinase. TO further evaluate whether LPA-induced tyrosine phosphorylation is catalyzed by intrinsic EGF receptor kinase or by another cellular kinase, Specific Aim II proposes phosphopeptide mapping and mutagenesis experiments to analyze LPA-induced tyrosine phosphorylation sites on the EGFR. In Specific Aim III, regulation of EGFR-dephosphorylating activity by LPA will be investigated both in vitro and in intact cells under conditions that redox-mediated changes can be detected, and the involvement of calcium and ROS will be evaluated. These studies not only will advance our understanding of signal transduction by LPA and G-proteins that control many cellular processes fundamental to the development of cancer and other human diseases, but also will stimulate further research in the emerging area of oxidative signaling.

溶血磷脂酸（LPA）是血清中的主要有丝分裂原，可调节 一系列与癌症发病机理有关的细胞过程 其他人类疾病。 尽管LPA在控制中的核心作用 细胞生长和其他细胞活性，很少了解 关于LPA的信号传导机制。而蛋白质酪氨酸 磷酸化已被认为是重要的信号传导机制 LPA和G蛋白偶联受体的其他激动剂，它仍然存在 G蛋白的激活在很大程度上未知会导致酪氨酸 磷酸化。 为了解决这个重要的问题，LPA引起的 表皮生长因子受体（EGFR）的酪氨酸磷酸化 将被研究。 基于我们的初步观察和增加 细胞信号中氧化还原调节的证据，据推测 LPA通过减少EGF受体磷酸酶来反式激活EGFR 通过钙和活性氧介导的机制的活性 物种（ROS）。 提出了三个特定的目标来进行批判性评估 该假设的关键方面。 在特定的目标I中，要求 固有的EGFR酪氨酸激酶活性将使用激酶进行评估 EGFR的EGFR缺陷和新的特异性抑制剂。 效果 降低蛋白质酪氨酸磷酸酶对EGFR的活性也将 被检查。 另外，提出了一种新颖的敏感方法 确定LPA是否激活EGFR激酶。进一步评估 LPA诱导的酪氨酸磷酸化是否由固有的 EGF受体激酶或其他细胞激酶，特定的AIM II 提出了磷酸肽映射和诱变实验以分析 LPA诱导的EGFR上的酪氨酸磷酸化位点。 在特定目标中 iii，LPA对EGFR - 脱磷酸化活性的调节将是 在条件下研究了体外和完整细胞 可以检测到氧化还原介导的变化，并参与钙 ROS将进行评估。 这些研究不仅会推进我们的 了解控制LPA和G蛋白的信号转导的理解 许多细胞过程是癌症发展和 其他人类疾病，但也会刺激进一步的研究 氧化信号传导的新兴区域。