Adaptor molecules in lymphocyte signaling

描述（由申请方提供）：T和B细胞上抗原受体的结合导致一系列信号级联的激活，包括细胞蛋白的磷酸化和Ras-MAPK途径和Ca 2+通量的激活。在T细胞中，膜相关的衔接分子LAT（用于活化T细胞的接头）通过将Grb 2、Gads和PLC-γ-1募集到膜上，在将TCR接合与Ras-MAPK活化和Ca 2+通量连接中起关键作用。然而，目前尚不清楚BCR参与如何耦合到Ras-MAPK激活和Ca 2+流量。在B细胞中尚未发现LAT样分子。最近，我们克隆了一个新的基因编码的膜相关衔接蛋白。我们将该基因命名为LAB（激活B细胞的连接子）。我们的初步数据表明，LAB与LAT有许多共同特征。我们假设，在B细胞中，LAB的功能是通过将Grb 2募集到细胞膜来将BCR接合与下游Ras-MAPK激活和Ca 2+通量偶联。本研究旨在进一步研究LAB在B细胞活化和发育中的作用。设计了三个具体目标来检验这一假设。在具体目标1中，将在鸡DT 40 B细胞系中破坏LAB基因。将表征由该基因缺失引起的信号传导缺陷。在具体目标2中，我们将使用转基因小鼠检查LAB和LAT之间的功能差异。在具体目标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.