MITOGENIC SIGNALING THROUGH RAL A AND PHOSPHOLIPASE D

通过 RAL A 和磷脂酶 D 的有丝分裂信号传导

• 批准号: 7050475
• 负责人: DAVID A FOSTER
• 金额: $ 5.31万
• 依托单位: HUNTER COLLEGE
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-08-25 至 2005-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7050475
• 关键词: biological signal transduction; enzyme activity; epidermal growth factor; growth factor receptors; guanine nucleotide exchange factors; intracellular transport; mitogens; phosphatidate; phospholipase D; protein transport; receptor mediated endocytosis; tissue /cell culture; vesicle /vacuole

This proposal seeks to understand the role that the RalA/phospholipase D (PLD) signaling pathway plays in mitogenic signaling. The applicant's laboratory has demonstrated that PLD activity is elevated in cells treated with a variety of mitogenic stimuli, and that this pathway is a critical mediator of transformation by v-Src, v-Raf, v-Ras, and overexpression of the EGF receptor. In normal quiescent cells, PLD is complexed with GDP-bound RalA and localized to cellular membranes. The enzyme becomes activated upon RalA GTP exchange and recruitment of Arf GTP to the complex, both events thought to be brought about by activation of Ras. However, Arf GTP does not bind the RalA/PLD complex directly, and elevated PLD activity in membranes of Ras-transformed cells requires the addition of cytosol. These findings suggest that an additional factor is needed for complete activation of PLD. PLD hydrolyzes phosphatidylcholine to phosphatidic acid (PA). PA is involved in many biological processes, including intracellular vesicle formation and activation of signaling molecules, but its exact role in promoting mitogenic signaling is not understood. Preliminary evidence from the applicant's lab suggests that PLD may play a role in EGF receptor endocytosis. Two aims are proposed to further investigate both the mechanism of PLD activation and its putative role in endocytosis. The first aim is to purify and characterize a recently discovered low molecular weight PLD-stimulating factor (PLD-SF) that is elevated in transformed and dividing cells. The second aim will test the hypothesis that PLD regulates intracellular signaling by facilitating receptor-mediated endocytosis to generate "signaling vesicles."

该提议试图了解 Rala/磷脂酶D（PLD）信号通路在有丝分裂信号中播放。这 申请人的实验室表明，PLD活性在细胞中升高 用多种有丝分裂刺激处理，该途径是 V-SRC，V-RAF，V-RAS和过表达的转化的关键介体 EGF受体的。在正常的静态细胞中，PLD与GDP结合 rala并局限于细胞膜。酶在 Rala GTP交换和将ARF GTP招募到该综合体，这两个事件 被认为是由RAS激活带来的。但是，ARF GTP没有 直接结合Rala/PLD复合物，并在膜上升高PLD活性 RAS转换的细胞需要添加细胞质。这些发现表明 完全激活PLD需要一个附加因素。 pld 将磷脂酰胆碱水解为磷脂酸（PA）。 PA参与 许多生物过程，包括细胞内囊泡形成和 信号分子的激活，但其在促进有丝分裂中的确切作用 信号不了解。申请人实验室的初步证据 表明PLD可能在EGF受体内吞作用中起作用。两个目标是 提议进一步研究PLD激活的机制及 假定的内吞作用。第一个目的是净化和表征 最近发现的低分子量PLD刺激因子（PLD-SF） 在转化和分裂的细胞中升高。第二个目标将测试 PLD通过促进来调节细胞内信号的假设 受体介导的内吞作用以产生“信号囊泡”。