Regulation of Ras signaling by the ubiquitin pathway

描述（由申请人提供）：通过众所周知的癌基因Ras发出的信号可以促进增殖、细胞存活和分化，并与癌症有关。通过这一途径增加信号的突变在癌症中经常发现，也发生在发育障碍中，如努南综合征。因此，了解Ras是如何调控的是至关重要的。很多注意力都集中在了解该途径在上游步骤的激活，例如配体与受体酪氨酸激酶（RTKs）的结合，RTKs通过其他蛋白质募集和激活Ras。最近，在哺乳动物细胞中发现了一种被称为泛素化的Ras修饰过程。我的研究小组现在用果蝇证实了Ras的泛素化。这表明新发现的Ras调控是高度保守的。此外，利用果蝇，我们获得了令人信服的证据，证明Ras的泛素化对生长、增殖和细胞存活有深远的影响。强大的果蝇遗传学系统和完善的果蝇Ras研究范式使其成为解决和表征Ras泛素化在多细胞环境中的重要性的绝佳系统。此外，在果蝇体内的方法有可能做出重大而独特的发现，这在其他系统中是不可能的。本提案的目标是利用果蝇来了解Ras泛素化的生物学作用。我们的假设是Ras的泛素化限制了它促进生长和增殖的能力。我们的假设是基于我们在果蝇上的发现：(1)果蝇的Ras是泛素化的，(2)泛素化损伤促进Ras信号的增加，(3)泛素化损伤促进Ras依赖的过度生长、增加、增殖和细胞死亡抵抗，这些抵抗与Ras上游的步骤无关。我们发现的新奇之处在于Ras可能是通路中一个独特的步骤，其泛素化对于确保适当控制生长和增殖至关重要。我的研究小组将利用我们在研究泛素途径和利用果蝇方面的专业知识来最有效地解决这个问题。拟议的研究完美地补充了正在进行的其他地方进行的分子和组织培养研究。在短期内，我们的研究可以确定这种新的Ras调控的生物学意义。从长远来看，我们的工作可以为更好地理解Ras癌基因做出巨大贡献，甚至可以确定治疗靶点。因此，我们相信这些研究可能会对癌症研究产生深远的影响。我们提出以下研究目标：具体目标1：确立Ras泛素化的生物学意义。特异性目的2：体内检测Ras泛素化。具体目标3：识别和表征Ras E3。公共卫生相关性：在发育障碍和癌症中经常发现激活一种叫做Ras的蛋白质或通过Ras途径增加信号的突变。因此，了解Ras信号是如何调控的是至关重要的。拟议的研究将通过一种被称为“泛素化”的过程来研究Ras的一种新的调控，这将极大地有助于更好地了解Ras，并可能对癌症研究产生深远的影响。

DESCRIPTION (provided by applicant): Signaling through the well-known oncogene Ras can promote proliferation, cell survival, and differentiation and is implicated in cancer. Mutations that increase signaling through this pathway are found frequently in cancer and also occur in developmental disorders such as Noonan's Syndrome. Thus, it is vital to understand how Ras is regulated. Much attention has focused on understanding activation of this pathway at upstream steps, such as the binding of ligands to Receptor Tyrosine Kinases (RTKs), which act through other proteins to recruit and activate Ras. Recently, modification of Ras by a process called ubiquitination has been reported in mammalian cells. My research group now has data confirming the ubiquitination of Ras using Drosophila (fruit flies). This suggests that this newly discovered regulation of Ras is highly conserved. Moreover, using Drosophila (fruit flies) we generated compelling evidence that the ubiquitination of Ras has profound effects on growth, proliferation and cell survival. The powerful system of Drosophila genetics and the well-established paradigm of studying Ras in Drosophila make this an excellent system to address and characterize the significance of Ras ubiquitination in a multi-cellular context. Furthermore, an in vivo Drosophila approach has the potential to make significant and unique discoveries that would not be possible in other systems. The goal of this proposal is to use Drosophila to understand the biological role of Ras ubiquitination. Our hypothesis is that ubiquitination of Ras restricts its ability to promote growth and proliferation. Our hypothesis is based on our Drosophila findings that (1) Drosophila Ras is ubiquitinated, (2) impairing ubiquitination promotes increased signaling through Ras, and (3) impairing ubiquitination promotes Ras-dependent overgrowth, increased, proliferation, and cell death resistance that appear independent of steps upstream of Ras. The novelty of our findings is that Ras may be a distinct step in the pathway whose ubiquitination is crucial to ensure proper control of growth and proliferation. My research group will exploit our expertise in studying the ubiquitin pathway and in utilizing Drosophila to most efficiently attack this problem. The proposed studies perfectly complement ongoing molecular and tissue culture studies being performed elsewhere. In the short term, our studies could establish the biological significance of this novel regulation of Ras. Over the longer term, our work could contribute tremendously towards a better understanding of the Ras oncogene and may even identify therapeutic targets. Therefore, we believe that these studies could have profound implications for cancer research. We propose research according to the following Aims: Specific Aim 1: Establish the biological significance of Ras ubiquitination. Specific Aim 2: Examine Ras ubiquitination in vivo. Specific Aim 3: Identify and characterize the Ras E3. PUBLIC HEALTH RELEVANCE: Mutations that activate a protein called Ras or that increase signaling through the Ras pathway are frequently found in developmental disorders and in cancer. Therefore, it is crucial that we understand how Ras signaling is regulated. The proposed studies will investigate a novel regulation of Ras by a process called "ubiquitination" and could contribute tremendously towards a better understanding of Ras and may have profound implications for cancer research.