Analysis of adaptor protein (LAT) in TCR signaling

TCR识别MHC-肽复合体激活Src和Syk家族酪氨酸激酶 诱导信号蛋白的磷酸化。其中一种显著的磷酸化蛋白质是LAT(接头 用于激活T细胞)。后者是一种棕榈酰化跨膜接头蛋白，与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激活和钙离子通量。之前对LAT的研究- 基因缺陷的Jurkat细胞表明LAT在TCP介导的信号转导和LAT中是必不可少的 棕榈酰化是LAT磷酸化和功能所必需的。LAT缺乏的小鼠早期就会受到抑制 胸腺细胞发育。最近的研究表明，LAT在T细胞动态平衡中也起着重要作用。 表达未能结合PLC-y1的LAT突变体的小鼠会患上严重的自身免疫性疾病。基于 目前的信息和我们的初步发现，我们建议，通过将TCR参与与RAS- MAPK激活和钙离子通量，LAT在调节T细胞的激活、存活和 动态平衡。有三个具体目标旨在检验这一假设，并进一步了解 后者在T细胞中发挥作用。在特定目标1中，我们将使用小鼠，在小鼠中，Lat基因可以被CRE删除 重组酶，研究LAT在胸腺细胞发育中的作用。在具体目标2中，我们将归纳 体内和体外Lat基因缺失以研究成熟T细胞的LAT功能。我们将重点关注 Lat和LAT-PLCY！TCR介导的信号转导、T细胞激活、内稳态增殖、 和细胞存活。在特定的目标3中，我们将使用LAT条件基因敲除小鼠来研究正常的LAT 功能是Treg细胞在外周生存所必需的。我们还将研究钙离子途径的作用。 在Treg细胞发育和自身免疫中，使用表达一种结构性活性形式的钙调神经磷酸酶的小鼠。 T细胞是我们免疫系统的中心组成部分。Lat是发挥重要作用的分子之一 在T细胞激活中的作用。LAT功能的测定及对TCR信号通路的进一步认识 可以促进设计一种合理的方法来增强或抑制自身免疫中的T细胞增殖， 过敏，以及组织和器官移植。

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-PLCy! 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.