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被扩增和过度表达，取消它们的活性可以改善预后和生存。尽管受体酪氨酸激酶下游有丝分裂通路的潜在机制已经被很好地了解了，但关于这些增殖信号是如何被关闭的却知之甚少。在识别EGF受体途径分子的蛋白质组学筛选中，我们先前已经发现Odin，一种新的酪氨酸磷酸化适配蛋白，包含PTB、Ankyrin和SAM结构域。我们已经证明，过表达ODIN会抑制生长因子诱导的成纤维细胞的信号传导和增殖。线虫中基于RNAi的Odin同源基因敲除会导致不育，这表明了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Grb2是一个与Odin相互作用的分子。 我们假设ODIN通过与Grb2结合并破坏Grb2/SOS/RAS复合体而发挥生长因子受体信号的负调控作用。基于我们的初步数据表明Odin以EGF诱导的方式与几种蛋白质结合，我们进一步假设Odin的不同结构域参与了这种多蛋白复合体的招募，这对Odin的功能至关重要。最后，我们假设Odin在通过激活的酪氨酸激酶转化成纤维细胞以及在乳腺发育和肿瘤形成中发挥作用。这一建议的意义在于，它将使我们能够确定有助于下调生长因子诱导的信号转导的生化机制，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了解将对在人类癌症治疗中针对细胞内信号分子的策略至关重要。

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.