REGULATION OF RAS EFFECTOR PATHWAYS

精确的信号通路，介导了细胞的转化和 突变的RAS蛋白的致癌作用仍有待确定。 首先，尽管RAS与Raf丝氨酸/苏氨酸相互作用 激酶显然对RAS转换很重要，RAS如何 促进Raf的激活仍然是复杂和未解决的。第二, 最近的研究清楚地表明，Raf依赖和Raf- 独立的效应通路对于促进完整的RAS是必不可少的 转型。例如，Raf不依赖的通路涉及 Rho家族蛋白已被证明对RAS很重要 激活Jun氨基末端激酶(JNK)途径。然而， 连接RAS和RHO的效应器尚不清楚。 该提案描述了三个具体目标，以进一步划定 介导RAS的下游相互作用和信号通路 致癌性。首先，我们最近展示了这种互动 RAS和RAF之间的关系比最初想象的要复杂得多。 不是简单地将RAS的开关I结构域结合到N- Raf中的末端RAS结合域，第二次相互作用 RAS开关II结构域和Raf富含半胱氨酸结构域(Raf-Cys) 也会发生。我们还定义了一个假定具有RAS约束力的共识 在Raf-Cys和其他候选RAS效应器中的序列(例如， RA1GDS)。第二种相互作用似乎对RAS至关重要 RAF的激活和RAS的转化。实验是 建议建立Raf-Cys在RAF激活RAS中的作用。 RalGDS是否与RAS交换机I和II交互也将 地址。其次，我们最近表明，PL20RAS缺口可能 特异性地调节Raf非依赖性信号通路，从而导致 JNK。将进行实验以确定pl 20RAS间隙 作为RAS和Rho家族蛋白之间的纽带， 引起JNK和血清反应因子的激活。最后，我们会 确定Rho家族成员rac1是否通过以下方式激活其效应器 与交换机I和II以及与其他C-端的相互作用 序列。确定调节RAS的关键组件 转换可以确定设计和设计的重要目标 癌症化疗新方法的发展。

The precise signaling pathways that mediate the transforming and oncogenic action of mutated Ras proteins remain to be defined. First, although Ras interaction with the Raf serine/threonine kinases is clearly important for Ras transformation, how Ras promotes Raf activation remains complex and unresolved. Second, recent studies clearly demonstrate that both Raf-dependent and Raf- independent effector pathways are essential to promote full Ras transformation. For example, a Raf-independent pathway involving Rho family proteins has been shown to be important for Ras activation of the Jun N-terminal kinase (JNK) pathway. However, the effector that connects Ras with Rho remains to be elucidated. This proposal describes three specific aims to further delineate the downstream interaCtions and signaling pathways that mediate Ras oncogenicity. First, we recently showed that the interaction between Ras and Raf is more complex than originally thought. Instead of a simple binding of the switch I domain of Ras to an N- terminal Ras binding domain in Raf, a second interaction between the Ras switch II domain and the Raf cysteine-rich domain (Raf-Cys) also occurs. We have also defined a putative consensus Ras-binding sequence in Raf-Cys and in other candidate Ras effectors (e.g., Ra1GDS). This second interaction appears to be critical for Ras activation of Raf and for Ras transformation. Experiments are proposed to establish the role of Raf-Cys in Ras activation of Raf. Whether RalGDS interacts with Ras switch I and II will also be addressed. Second, we recently showed that pl 20 Ras GAP may specifically modulate a Raf-independent signaling pathway leading to JNK. Experiments will be performed to determine if pl 20 Ras GAP serves as the link between Ras and the Rho family proteins, to cause activation of JNK and serum response factor. Finally, we will determine if the Rho family member Rac1 activates its effectors by interactions with switch I and II, and with other C-terminal sequences. The identification of key components that mediate Ras transformation may identify important targets for the design and development of novel cancer chemotherapeutic approaches.