Adaptor molecules in lymphocyte signaling

描述（由申请人提供）：抗原受体在T细胞和B细胞上的结合导致一系列信号级联反应的激活，包括细胞蛋白的磷酸化和Ras-MAPK途径和ca2 +通量的激活。在T细胞中，膜相关的接头分子LAT （T细胞活化的连接物）通过将Grb2、Gads和plc - γ -1募集到膜上，在连接TCR接合到Ras-MAPK活化和ca2 +通量方面起着至关重要的作用。然而，目前尚不清楚BCR参与是如何与Ras-MAPK激活和ca2 +通量耦合的。在B细胞中还没有发现类似lata的分子。最近，我们克隆了一个编码膜相关接头蛋白的新基因。我们将这个基因命名为LAB （B细胞活化连接子）。我们的初步数据表明，LAB与LAT具有许多共同特征。我们假设，在B细胞中，LAB通过将Grb2招募到膜上，将BCR与下游Ras-MAPK激活和ca2 +通量结合起来。本课题旨在进一步研究LAB在B细胞活化和发育中的作用。为了验证这一假设，设计了三个具体目标。在特异性目的1中，鸡DT40 B细胞系的LAB基因将被破坏。由该基因缺失引起的信号缺陷将被表征。在具体目标2中，我们将使用转基因小鼠来研究LAB和LAT之间的功能差异。在特定目的3中，将在小鼠中破坏LAB基因以研究LAB在B细胞发育中的功能。我们还将研究LAB在血小板和NK细胞中的功能。

DESCRIPTION(provided by applicant): Engagement of antigen receptors on T and B cells leads to activation of a series of signaling cascades, including phosphorylation of cellular proteins and activation of the Ras-MAPK pathway and Ca 2+ flux. In T cells, the membrane-associated adaptor molecule, LAT (Linker for activation of T cells), plays a crucial role in connecting the TCR engagement to Ras-MAPK activation and Ca 2+ flux by recruiting Grb2, Gads, and PLC-gamma-1 to the membrane. However, it is not clear how the BCR engagement is coupled to Ras-MAPK activation and Ca 2+ flux. A LAT-like molecule has not been found in B cells. Recently, we cloned a novel gene encoding a membrane-associated adaptor protein. We named this gene, LAB (Linker for activation of B cells). Our preliminary data showed that LAB shares many characteristics with LAT. We hypothesize that, in B cells, LAB functions to couple the BCR engagement to downstream Ras-MAPK activation and Ca 2+ flux by recruiting Grb2 to the membrane. This proposal aims to further study LAB function in B cell activation and development. Three specific aims are designed to test this hypothesis. In specific aim 1, LAB gene will be disrupted in the chicken DT40 B cell line. Signaling defects caused by deletion of this gene will be characterized. In specific aim 2, we will examine the functional differences between LAB and LAT using transgenic mice. In specific aim 3, LAB gene will be disrupted in mice to study LAB function in B cell development. We will also study LAB function in platelets and NK cells.