Analysis of adaptor protein (LAT) in TCR signaling

描述（由申请人提供）：TCR对mhc肽复合物的识别激活Src和Syk家族酪氨酸激酶并诱导信号蛋白磷酸化。其中一个显著的磷酸化蛋白是LAT（激活T细胞的连接物）。LAT是一种棕榈酰化的跨膜衔接蛋白，它结合Grb2、Gads、PLC- y1和其他信号分子，从而将这些分子招募到质膜上，激活下游信号事件，如Ras-MAPK激活和Ca2+通量。先前对LAT缺乏的Jurkat细胞的研究表明，LAT在tcp介导的信号转导中是必不可少的，LAT棕榈酰化是LAT磷酸化和功能所必需的。lat缺陷小鼠胸腺细胞发育早期阻滞。最近的研究表明，LAT在T细胞稳态中也起着重要的作用。表达不能结合PLC-y1的LAT突变体的小鼠会发生严重的自身免疫性疾病。基于目前的信息和我们的初步研究结果，我们提出，通过将TCR与Ras- MAPK激活和Ca2+通量耦合，LAT在调节T细胞激活、存活和稳态中发挥重要作用。有三个特定的目标旨在验证这一假设，并进一步了解LAT在T细胞中的功能。在特定的目的1中，我们将使用可以通过Cre重组酶删除Lat基因的小鼠来研究Lat在胸腺细胞发育中的作用。在具体目标2中，我们将在体内和体外诱导Lat基因的缺失，以研究Lat在成熟T细胞中的功能。我们将重点讨论LAT和LAT- plc的作用。tcr介导的信号、T细胞激活、稳态增殖和细胞存活的相互作用。在具体目标3中，我们将使用LAT条件敲除小鼠来研究外周Treg细胞存活是否需要正常的LAT功能。我们还将研究Ca2+通路在Treg细胞发育和自身免疫中的作用，使用表达钙调磷酸酶组成活性形式的小鼠。T细胞是我们免疫系统的核心组成部分。LAT是T细胞活化中起重要作用的分子之一。确定LAT功能和进一步了解TCR信号通路有助于设计一种合理的方法来增强或抑制T细胞在自身免疫、过敏和组织器官移植中的增殖。

DESCRIPTION (provided by applicant): Recognition of MHC-peptide complexes by the TCR activates Src and Syk family tyrosine kinases and induces phosphorylation of signaling proteins. One of the prominently phosphorylated proteins is LAT (linker for activation of T cells). LAT is a palmitoylated transmembrane adaptor protein that binds Grb2, Gads, PLC- y1, and other signaling molecules, thus recruiting these molecules to the plasma membrane to activate downstream signaling events, such as Ras-MAPK activation and Ca2+ flux. Previous studies with LAT- deficient Jurkat cells demonstrate that LAT is essential for TCP-mediated signal transduction and LAT palmitoylation is required for LAT phosphorylation and function. LAT-deficient mice have an early block in thymocyte development. Recent studies show that LAT also plays an important role in T cell homeostasis. Mice that express a LAT mutant that fails to bind PLC-y1 develop a severe autoimmune disease. Based on current information and our preliminary findings, we propose that, by coupling TCR engagement to Ras- MAPK activation and Ca2+ flux, LAT plays an important role in regulating T cell activation, survival, and homeostasis. There are three specific aims designed to test this hypothesis and to further understand how LAT functions in T cells. In specific aim 1, we will use mice, in which the Lat gene can be deleted by the Cre recombinase, to study the role of LAT during thymocyte development. In specific aim 2, we will induce deletion of the Lat gene in vivo and in vitro to study LAT function in mature T cells. We will focus on the role of LAT and the LAT-PLC? interaction in TCR-mediated signaling, T cell activation, homeostatic proliferation, and cell survival. In specific aim 3, we will use LAT conditional knockout mice to study whether normal LAT function is required for Treg cell survival in the periphery. We will also investigate the role of the Ca2+ pathway in Treg cell development and autoimmunity using mice that express a constitutively active form of calcineurin. T cells are the central components of our immune system. LAT is one of the molecules that play essential roles in T cell activation. Determination of LAT function and further understanding TCR signaling pathway could facilitate the design of a rational approach to augment or inhibit T cell proliferation in autoimmunity, allergy, and tissue and organ transplantation.