GAB2 AND A NOVEL CYTOPLASMIC NUCLEAR SIGNALING MECHANISM

描述(改编自申请者的摘要)：一个中心问题 在细胞调节中涉及的是许多生物化学机制 不同类型的信号蛋白和酶协同工作以调节 细胞对特定细胞外刺激的反应。我们才刚刚开始 认识到支架或接头蛋白可能在 从质膜到细胞内靶点的信号传递通过聚集 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Gab2，它与 与Gab I(Grb2相关结合蛋白1)和果蝇Dos(Dos的女儿 七点半)。Gabi和Gab2都含有一个PH结构域和多重电势 SH2蛋白的酪氨酸磷酸化位点以及富含脯氨酸的基序 用于SH3结合。有趣的是，我们发现Gabi和Gab2展示了 胞质-核信号耦合中的互易功能，以及Gab2 抑制小鼠体内转录因子Elk-I的活性 致癌RASV 12或表皮生长因子，无下调 细胞外信号调节激酶(ERK)活性。我们假设Gab2 作用于聚集一组独特的酶及其特定的底物 信号传递是细胞内一条新的、未被探索的途径 发信号。这项提案的目标是为 Gb2在信号转导中的负性作用。这将通过以下方式实现： 1)。Gb2基因中与阴性有关的结构域的鉴定 监管角色；2)。蛋白质的分离和功能分析 通过“负效应域”与Gab2相互作用；澄清： Gab2与其伙伴相互作用的生理结果； Gb2基因体内生物学功能的测定 Gb2基因缺陷小鼠模型。这项工作将使我们能够更好地理解 实现细胞内信号转导特异性的机制 通过支架组织多分子复合体(信号体) 蛋白质，如Gab2，并将有助于设计有效的药物 干预某些与心力衰竭相关的细胞紊乱， 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.