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的信号传导可促进增殖、细胞存活和分化，并与癌症有关。通过该途径增加信号传导的突变经常在癌症中发现，并且也发生在发育障碍如努南综合征中。因此，了解Ras是如何调节的至关重要。许多注意力集中在理解该途径在上游步骤的激活，例如配体与受体酪氨酸激酶（RTK）的结合，其通过其他蛋白质来募集和激活Ras。最近，在哺乳动物细胞中已经报道了通过称为泛素化的过程修饰Ras。我的研究小组现在有数据证实Ras在果蝇中的泛素化。这表明新发现的Ras调控是高度保守的。此外，使用果蝇（果蝇），我们产生了令人信服的证据表明，Ras的泛素化对生长，增殖和细胞存活具有深远的影响。果蝇遗传学的强大系统和在果蝇中研究Ras的成熟范式使其成为一个很好的系统来解决和表征Ras泛素化在多细胞背景下的意义。此外，果蝇的体内方法有可能取得在其他系统中不可能的重大和独特的发现。这个提议的目的是利用果蝇来了解Ras泛素化的生物学作用。我们的假设是Ras的泛素化限制了其促进生长和增殖的能力。我们的假设是基于我们在果蝇中的发现，即（1）果蝇Ras是泛素化的，（2）泛素化受损促进通过Ras的信号传导增加，（3）泛素化受损促进Ras依赖性过度生长，增加增殖和细胞死亡抗性，这些似乎独立于Ras上游的步骤。我们发现的新奇在于Ras可能是途径中的一个独特步骤，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方面的专业知识，并利用果蝇来最有效地解决这个问题。拟议的研究完美地补充了其他地方正在进行的分子和组织培养研究。在短期内，我们的研究可以建立这种新的Ras调节的生物学意义。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对癌症研究产生深远的影响。我们根据以下目的提出研究：具体目标1：确定Ras遍在化的生物学意义。具体目标2：检查Ras在体内的泛素化。具体目标3：鉴定和表征Ras E3。公共卫生相关性：激活Ras蛋白或通过Ras途径增加信号传导的突变经常在发育障碍和癌症中发现。因此，了解Ras信号是如何调节的至关重要。拟议的研究将通过一种称为“泛素化”的过程来研究Ras的一种新的调节，这可能有助于更好地理解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.