PHOSPHOLIPASE D ACTIVATION BY V-SCR AND V-RAS

V-Src和v-ras激活磷脂酶D对致癌效应的影响 在v-Src的刺激下，存在磷脂酶D(PLD)的激活，即 依赖于RAS和RAL的GTP酶级联。V-Src的转换是 也依赖于RAS和RAL，提示PLD在细胞中的作用 转型。磷脂酰胆碱将磷脂酰胆碱水解为磷脂酸 (PA)和胆碱。对PA最了解的作用是由PA介导的 代谢物二酰甘油，导致蛋白激酶激活 C.然而，PA也具有生物活性，并与 调节包括Raf-L在内的多种信号分子， 磷脂酰肌醇激酶和GTP酶激活蛋白(GAP) RAS、RAC和ARF。PLD活性和PA也与囊泡有关 运输。 尽管v-Src诱导的PLD活性需要Rala，并且PLD存在于 与RAL形成的复合体，激活的RALA不足以激活PLD。 生化和遗传证据表明，至少有两个因素 到Rala是由v-Src激活PLD所必需的。该计划的目标是 建议的研究是描述Rala和PLD之间的相互作用 并找出导致PLD通过新的 新出现的RAS/RAL信号通路。候选蛋白质牵涉到 由v-Src激活的PLD是Rho家族GTP酶Rho、Rac、CDC42和 Rala结合蛋白Ral-BP1，是Rho家族的GAP蛋白 GTP酶。ARF(ADP核糖化因子)，激活PLD相关的 和拉拉在一起的是另一个候选人。拟议的研究将测试这些 而其他相关因素参与了v-Src对PLD的激活。 因为许多细胞外刺激通过酪氨酸激活PLD 激酶和许多细胞内对PLD产生的PA的反应， 了解酪氨酸激酶激活PLD的机制 为疾病的治疗干预提供了几个新的靶点 与人类乳腺癌一样，酪氨酸激酶活性的调节发生了变化 已经被牵连了。

Phospholipase D Activation by v-Src and v-Ras: In response to the oncogenic stimuli of v-Src, there is an activation of phospholipase D (PLD) that is dependent upon a GTPase cascade of Ras and Ral. Transformation by v-Src is also dependent upon both Ras and Ral, suggesting a role for PLD in cell transformation. PLD hydrolyzes phosphatidylcholine to phosphatidic acid (PA) and choline. The best understood effects of PA are mediated by the PA metabolite diacylglycerol, which leads to the activation of protein kinase C. However, PA is also biologically active and has been implicated in regulating a variety of signaling molecules including Raf-l, phosphatidylinositol kinases, and the GTPase activating proteins (GAPs) for Ras, Rac and Arf. PLD activity and PA have also been implicated in vesicle transport. Although RalA is required for v-Src-induced PLD activity and PLD exists in a complex with Ral, an activated RalA is not sufficient for PLD activation. Biochemical and genetic evidence suggest at least two factors in addition to RalA are required for PLD activation by v-Src. The objective of the proposed studies is to characterize the interaction between RalA and PLD and to identify factors contributing to the activation of PLD via the newly emerging Ras/Ral signaling pathway. Candidate proteins implicated in the activation of PLD by v-Src are the Rho family GTPases Rho, Rac, Cdc42 and the RalA binding protein Ral-BP1, which is a GAP protein for Rho family GTPases. Arf (ADP ribosylation factor), which activates the PLD associated with RalA is another candidate. Proposed studies will test whether these and other implicated factors contribute to activation of PLD by v-Src. Because of the many extracellular stimuli that activate PLD via tyrosine kinases and the many intracellular responses to the PLD-generated PA, understanding of the mechanism of PLD activation by tyrosine kinases will provide several new targets for therapeutic intervention in diseases such as human breast cancer where altered regulation of tyrosine kinase activity has been implicated.