GAB2 AND A NOVEL CYTOPLASMIC NUCLEAR SIGNALING MECHANISM

描述（改编自申请人的摘要）：一个中心问题， 在细胞调节中涉及的是许多生物化学机制， 不同种类的信号蛋白和酶协同工作， 细胞对特定细胞外刺激的反应。我们才刚刚开始 为了理解支架或衔接蛋白在细胞内的细胞增殖中可能发挥重要作用， 通过聚集一个或多个细胞因子， 各种蛋白质进入特定的信号通路或网络。我们和其他人 最近发现了一种新的人类支架蛋白Gab 2， 与Gab I（Grb 2相关结合物1）和果蝇Dos（Dos的女儿）相关。 sevenless）。Gabi和Gab 2都含有PH结构域和多重势 SH 2蛋白的酪氨酸磷酸化位点以及富含脯氨酸的基序 用于SH 3结合。有趣的是，我们发现Gabi和Gab 2 在耦合细胞质-核信号传导中的相互作用，Gab 2 作用于抑制转录因子Elk-1的活性， 致癌RasV 12或表皮生长因子，而不下调 细胞外信号调节激酶（Erk）活性。我们假设Gab 2 作用是聚集一组独特的酶及其特定底物， 信号传递，这是一个新的和未开发的途径，在细胞内 发信号。本提案的目标是剖析这一途径， Gab 2在信号转导中的负效应。这将通过以下方式实现： 1）。确定了负相关的Gab 2结构域， 监管作用; 2）。蛋白质的分离和功能分析， 通过“负效应域”与Gab 2相互作用; 3）.阐明 Gab 2与其伴侣相互作用的生理后果;以及4）. 通过产生一种新的生物学功能测定Gab 2在体内的生物学功能， Gab 2缺陷小鼠模型。这项工作将使我们能够更好地了解 实现细胞内信号传导特异性的机制 通过支架组织多分子复合物（信号体） 蛋白质，如Gab 2，也将有助于设计有效的药物 某些与心力衰竭相关的细胞疾病的干预， 糖尿病和恶性疾病。

DESCRIPTION (adapted from applicant's abstract): A central question to be addressed in cell regulation is the biochemical mechanism by which many different kinds of signaling proteins and enzymes work in concert to mediate cellular responses to a specific extracellular stimulus. We are just beginning to appreciate that scaffold or adapter proteins may play important roles in signal relay from the plasma membrane to intracellular targets by aggregating a variety of proteins into specific signaling pathways or networks. We and others have recently identified a novel human scaffold protein, Gab2, that is closely related to Gab I (Grb2-associated binder 1) and Drosophila Dos (daughter of sevenless). Both Gabi and Gab2 contain a PH domain and mutliple potential tyrosine phosphorylation sites for SH2 proteins as well as proline-rich motifs for SH3 binding. Interestingly, we have found that Gabi and Gab2 exhibit reciprocal functions in coupling cytoplasmic-nuclear signaling, and that Gab2 acts to suppress the activity of the transcription factor Elk-i induced by oncogenic RasV 12 or epidermal growth factor, without down-regulating extracellular signal-regulated kinase (Erk) activity. We hypothesize that Gab2 acts to aggregate a unique set of enzymes and their specific substrates for signal relay, which represents a novel and unexplored pathway in intracellular signaling. The goal of this proposal is to dissect this pathway for the negative effect of Gab2 in signal transduction. This will be accomplished by: 1). identification of the structural domain in Gab2 involved in the negative regulatory role; 2). isolation and functional analysis of proteins that interact with Gab2 through the "negative effect domain"; 3). elucidation of the physiological consequence of the Gab2 interaction with its partners; and 4). determination of the biological function of Gab2 in vivo by generating a Gab2-deficient mouse model. This work will enable us to understand better the mechanism whereby the specificity of intracellular signaling is achieved through organization of multimolecular complexes (signalsomes) by scaffold proteins, such as Gab2, and will also aid in designing efficient pharmaceutical intervention of certain cellular disorders associated with heart failure, diabetes and malignant diseases.