Molecular Dissection of Growth Factor Receptor Signaling

描述（由申请人提供）：酪氨酸激酶活性失调与大量人类癌症有关。表皮生长因子受体家族的几个成员在人类肿瘤中扩增和过表达，并且其活性的消除可以导致改善的预后和存活。虽然受体酪氨酸激酶下游的促有丝分裂途径的机制已经很清楚，但对这些增殖信号是如何被关闭的知之甚少。在蛋白质组学筛选，以确定EGF受体途径中的分子，我们以前已经确定了奥丁，一种新的酪氨酸磷酸化衔接蛋白含有PTB，锚蛋白和SAM域。我们已经证明Odin的过度表达导致生长因子诱导的信号传导和成纤维细胞增殖的抑制。基于RNAi的C. elegans导致不育，表明这种进化上保守的分子的重要性。在初步研究中，我们已经确定Grb 2是一种与Odin相互作用的分子。 我们假设Odin通过与Grb 2结合并破坏Grb 2/Sos/Ras复合物来作为生长因子受体信号传导的负调节剂。基于我们的初步数据表明奥丁协会与几种蛋白质在EGF诱导的方式，我们进一步假设，奥丁的不同领域参与招聘的多蛋白复合物，这是至关重要的奥丁功能。最后，我们假设Odin在活化酪氨酸激酶转化成纤维细胞以及乳腺发育和肿瘤形成中发挥作用。这一建议的意义在于，它将使我们能够定义有助于下调生长因子诱导的信号传导的生化机制，以及阐明Odin在乳腺组织中的体内相关性。对这种抑制机制的详细理解对于靶向细胞内信号分子治疗人类癌症的策略至关重要。

DESCRIPTION (provided by applicant): Dysregulated tyrosine kinase activity is implicated in a large number of human cancers. Several members of the epidermal growth factor receptor family are amplified and overexpressed in human tumors and abrogation of their activity can lead to improved prognosis and survival. Although the mechanisms underlying the mitogenic pathways downstream of receptor tyrosine kinases are quite well understood, little is known about how these proliferative signals are shut off. In a proteomic screen to identify molecules in the EGF receptor pathway, we have previously identified Odin, a novel tyrosine-phosphorylated adapter protein containing PTB, Ankyrin and SAM domains. We have demonstrated that overexpression of Odin leads to inhibition of growth factor-induced signaling and proliferation in fibroblasts. RNAi-based knockdown of Odin ortholog in C. elegans leads to sterility indicating the importance of this evolutionarily conserved molecule. In preliminary studies, we have identified Grb2 as a molecule that interacts with Odin. We hypothesize that Odin acts as a negative regulator of growth factor receptor signaling by binding to Grb2 and disrupting the Grb2/Sos/Ras complex. Based on our preliminary data demonstrating association of Odin with several proteins in an EGF-inducible fashion, we further hypothesize that different domains of Odin participate in the recruitment of this multiprotein complex, which is crucial for Odin function. Finally, we hypothesize that Odin plays a role in transformation of fibroblasts by activated tyrosine kinases and in mammary gland development and tumor formation. The significance of this proposal is that it will allow us to define the biochemical mechanisms that help downregulate growth factor induced signaling as well as elucidate the in vivo relevance of Odin in mammary tissue. A detailed understanding of such inhibitory mechanisms will be crucial for strategies that target intracellular signaling molecules in the treatment of human cancers.