PHOSPHOLIPASE D ACTIVATION BY V-SCR AND V-RAS

v-Src和v-Ras激活磷脂酶D：对致癌基因的应答 在v-Src的刺激下，存在磷脂酶D（PLD）的激活， 依赖于Ras和Ral的GTP酶级联反应。通过v-Src的转换是 也依赖于Ras和Ral，表明PLD在细胞中的作用。 转型PLD水解磷脂酰胆碱生成磷脂酸 (PA)和胆碱。PA的最佳作用是由PA介导的， 代谢产物甘油二酯，其导致蛋白激酶的活化 C.然而，PA也是生物活性的，并且已经涉及到 调节多种信号分子包括Raf-I， 磷脂酰肌醇激酶，和GTP酶激活蛋白（GAP）， 拉斯，拉克和阿尔夫。PLD活性和PA也与囊泡的形成有关。 运输 尽管RalA是v-Src诱导的PLD活性所必需的，并且PLD存在于 与Ral的复合物，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v-Src激活PLD所必需的。的目的 拟议的研究是表征RalA和PLD之间的相互作用 并通过新的免疫抑制剂来识别有助于PLD激活的因素。 Ras/Ral信号通路。与肿瘤相关的候选蛋白质 通过v-Src激活PLD的是Rho家族GTP酶Rho、Rac、Cdc 42和 RalA结合蛋白Ral-BP 1是Rho家族GAP蛋白 GTP酶。Arf（ADP核糖基化因子），激活PLD相关的 RalA是另一个候选人。拟议的研究将测试这些 其他相关因素也参与了v-Src对PLD的激活。 由于许多细胞外刺激通过酪氨酸激活PLD 激酶和对PLD产生的PA的许多细胞内反应， 了解酪氨酸激酶激活PLD的机制将 为疾病的治疗干预提供了几个新的靶点， 作为人乳腺癌，其中改变了酪氨酸激酶活性的调节， 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.