The Role of GAB1:JNK2alpha2 Complex in Glial Tumorigenesis

描述（由申请人提供）：称为多形性胶质母细胞瘤的高级别人脑肿瘤的特征是细胞增殖增加、抗凋亡和血管分布增强。分子机制的研究强烈涉及受体酪氨酸激酶途径。本项目的目的是研究这些酪氨酸激酶受体的下游通路，希望能提高我们对神经胶质肿瘤发生的理解。更好地了解这些途径将有望引导我们改进针对恶性脑肿瘤的治疗方法。Albert Wong博士实验室先前的工作表明，JNK 2a 2的表达促进了几种致瘤表型，包括细胞生长和致瘤性。他的实验室还克隆了Gab 1对接蛋白，这是受体酪氨酸激酶途径的重要组成部分，促进细胞生长，存活和血管分布。有强有力的证据表明，Gab 1作为JNK和ERK功能的重要附件。ERK与存在于Gab 1中的Met结合结构域（MBD）结合，这可导致Gab 1被ERK磷酸化。Gab 1对于ERK功能是必不可少的，因为ERK缺乏核定位信号（NLS），而是依赖于其与具有NLS的Gab 1的结合来输入到细胞核中。现已发现Gab 1对H2 O2刺激后JNK的激活是必不可少的，并且JNK也与Gab 1相关。基于这些原因，我们认为Gab 1是细胞中JNK 2a 2功能的重要组成部分。本项目的目标是确定Gab 1：JNK 2a 2复合物在介导JNK 2a 2信号传导中的作用及其在神经胶质肿瘤发生中的作用。在第一个具体目标中，我们将首先在Gab 1上建立与JNK 2a 2相互作用的位点。使用这些信息，在特定的目标#2中，我们将确定Gab 1：JNK 2a 2复合物直接相互作用的位置。如果我们发现活性Gab 1：JNK 2a 2复合物定位于细胞核，我们将确认这是由于Gab 1的核转运。在具体目标#3中，我们将确定Gab 1：JNK 2a 2复合物在介导AKT和PI 3-激酶活化中的作用。使用干扰JNK 2a 2结合的Gab 1显性负突变体，我们将证明这对干扰神经胶质肿瘤表型的几个方面有影响。最终，这些信息可能有助于设计下调脑肿瘤信号通路的治疗方法。简单地说，我们正在研究恶性脑肿瘤的分子生物学，希望找到更好的治疗方案。

DESCRIPTION (provided by applicant): The high grade human brain tumors known as glioblastoma multiforme are characterized by an increase in cell proliferation, resistance to apoptosis, and enhanced vascularity. The search for the molecular mechanisms has strongly implicated receptor tyrosine kinases pathways. The objective of this project is to study the downstream pathways for these tyrosine kinase receptors in hopes to improve our understanding of glial tumorigenesis. A better understanding of these pathways will hopefully lead us to improved therapeutics directed at malignant brain tumors. Previous work in the lab of Dr. Albert Wong has shown that expression of JNK2a2 promotes several tumorigenic phenotypes including cell growth and tumorigenicity. His lab also cloned the Gab1 docking protein, which is an essential component in receptor tyrosine kinases pathways that promotes cell growth, survival, and vascularity. There is strong evidence that Gab1 acts as an important accessory for JNK and ERK function. ERK binds to the Met binding domain (MBD) present in Gab1 and this can result in Gab1 phosphorylation by ERK. Gab1 is essential for ERK function as ERK lacks a nuclear localization signal (NLS) and instead relies on its association with Gab1, which does have a NLS, for importation into the nucleus. It has been found that Gab1 is essential for the activation of JNK following stimulation by H2O2 and that JNK also associates with Gab1. For these reasons, we believe that Gab1 is an essential component for JNK2a2 function in cells. The goal of this project is to determine the role of the Gab1: JNK2a2 complex in mediating JNK2a2 signaling and its role in glial tumorigenesis. In the first specific aim, we will first establish the site on Gab1 that interacts with JNK2a2. Using this information, in specific Aim #2, we will determine where the Gab1: JNK2a2 complexes directly interact. Should we find that the active Gab1: JNK2a2 complex localizes to the nucleus, we will confirm that this is due to the nuclear transport by Gab1. In specific aim #3, we will determine the role of the Gab1:JNK2a2 complex in mediating AKT and PI 3-kinase activation. Using dominant negative mutants of Gab1 that interfere with the binding to JNK2a2, we will show that this has an effect on interfering with several aspects of the glial tumor phenotypes. Ultimately, this information may be useful for designing therapeutics for the downregulation of signaling pathways in brain tumors. In plain language, we are studying the molecular biology of malignant brain tumors in hope to find better treatment options for this tumor.