Regulation of TCR Signaling by Sts-1 and Sts-2

描述(由申请人提供)：允许T细胞产生有效免疫反应的相同特性可以被用来对抗宿主组织，引发自身免疫反应。有趣的是，T细胞的自身反应往往是T细胞内信号通路失控的结果。因此，要了解不同自身免疫性疾病的病因，就需要对控制T细胞激活的机制有一个彻底和完整的了解。我研究的长期目标是了解T细胞激活的调节。目前，我的实验室正在研究两种相关蛋白质Sts-1和Sts-2如何协同作用，负向调节T细胞信号通路。Sts蛋白具有独特的模块化结构，具有N端泛素相互作用结构域(UBA)、中央蛋白质相互作用结构域(SH3)和与磷酸甘油酸变构酶(PGM)同源的C末端区域。通过对缺乏Sts-1和Sts-2的小鼠的分析，人们认识到Sts蛋白在调节TCR信号通路中具有作用。来自Sts-1/2-/-小鼠的T细胞在TCR刺激下显著过度增殖。在多发性硬化症的小鼠模型中，伴随这种高增殖表型的是TCR下游信号通路的激活增加，细胞因子产生水平的提高，以及Sts-1/2-/-小鼠对自身免疫的易感性增加。在我们正在进行的对Sts蛋白功能的研究中，我们最近发现了一种与Sts PGM结构域相关的新的蛋白酪氨酸磷酸酶活性。有趣的是，Sts磷酸酶结构域在初级氨基酸序列和重要的催化特性上与经典的PTPs没有相似之处。再加上没有已知的PTP包含UBA或SH3结构域，我们的结果表明Sts蛋白在T细胞内的一个细胞内信号利基中工作，这与经典的PTP是分开的和不同的。本提案中概述的实验旨在研究Sts-1和Sts-2的潜在功能(S)和作用机制(S)。我们的具体目标是：1.确定Sts蛋白如何通过调节ZAP-70来调节T细胞激活阈值。2.确定三个Sts模块结构域(UBA、SH3、PGM)如何协同负调控TCR信号通路。我们将结合使用生化、生物物理和细胞生物学方法来实现我们的目标。本文描述的研究的完成将帮助我们建立Sts蛋白如何协作负调控TCR信号通路的模型。

DESCRIPTION (provided by applicant): The same properties that allow T cells to mount an effective immune response can be turned against host tissue, provoking an autoimmune response. Intriguingly, T cell auto-reactivity is often the result of deregulated signaling pathways within T cells. Thus, understanding the etiology of different autoimmune diseases will require a thorough and integrated understanding of the mechanisms that control T cell activation. The long-term objective of my research is to understand the regulation of T cell activation. Currently, my laboratory is studying how two related proteins, Sts-1 and Sts-2, act in concert to negatively regulate T cell signaling pathways. The Sts proteins have a unique modular structure, with an N- terminal ubiquitin-interacting domain (UBA), a central protein-protein interaction domain (SH3), and a C- terminal region with homology to the enzyme phosphoglycerate mutase (PGM). The realization that the Sts proteins have a role in regulating TCR signaling pathways emerged from an analysis of mice lacking Sts-1 and -2. T cells from Sts-1/2-/- mice dramatically hyper-proliferate in response to TCR stimulation. This hyper- proliferative phenotype is accompanied by increased activation of signaling pathways downstream of the TCR, elevated levels of cytokine production, and increased susceptibility of Sts-1/2-/- mice to autoimmunity in a mouse model of multiple sclerosis. In our ongoing effort to characterize the functions of the Sts proteins, we recently discovered a novel protein tyrosine phosphatase activity associated with the Sts PGM domain. Intriguingly, the Sts phosphatase domain shows no similarity to classical PTPs in primary amino acid sequence and important catalytic features. Coupled with the fact that no known PTP contains a UBA or SH3 domain, our results suggest that the Sts proteins operate in an intracellular signaling niche within T cells that is separate and distinct from classical PTPs. The experiments outlined in this proposal are designed to address the underlying function(s) and mechanism(s) of action of the Sts-1 and Sts-2. Our Specific Aims are: 1. Determine how the Sts proteins regulate T cell activation thresholds via regulation of Zap-70. 2. Determine how the three Sts modular domains (UBA, SH3, PGM) cooperate to negatively regulate TCR signaling pathways. We will use a combination of biochemical, biophysical, and cell biological approaches to accomplish our goals. Completion of the studies described herein will help us build a model of how the Sts proteins cooperate to negatively regulate TCR signaling pathways.