Role of PTPRkappa in Lck Regulation During T cell Development

描述（由申请人提供）：免疫系统是一个相关的靶标，用于分析细胞如何解释它们通过表面受体接收的无数信号，从而决定它们的命运和/或功能反应。这些过程的改变有助于白血病和其他癌症的发展，也可能使个体易患自身免疫性疾病。这个项目的重点是CD4辅助性T细胞如何在胸腺中产生。据推测，蛋白酪氨酸磷酸酶受体kappa （PTPRk）在LEC大鼠中负责CD4 T细胞发育缺陷，通过调节Lck激酶活性在CD4谱系承诺中起核心作用。为了验证这一假设，目标包括：1。确定PTPRk表达水平的变化是否会改变谱系承诺；2. 表明Lck是PTPRk的底物；和3。确定在CD4谱系承诺过程中调节T细胞受体介导的PTPRk表达的机制。PTPRk水平将通过基因构建改变T细胞受体Tg原代细胞，注射到受体小鼠中，然后检查谱系转移。对Lck活性的影响将通过体外磷酸酶测定以及通过相关细胞系在体内进行测试。PTPRk的表达模式将通过定量RT-PCR在发育中间群体中进行检测。功能丧失方法将有助于确定受PTPRk影响的积极选择途径。我们提出了一个模型，其中强Lck信号诱导PTPRK，然后通过残基Y505的Lck去磷酸化来促进Lck的持续激活。这种正反馈循环使细胞能够向CD4谱系靠拢。对PTPRK等T细胞信号蛋白的研究将扩大我们对免疫系统发育的理解，特别是对建立辅助性T细胞功能程序的分化事件序列的理解。更好地了解T细胞谱系决定和蛋白质之间信号传导的变化如何导致T细胞相关白血病、淋巴瘤的形成，以及导致自身免疫的耐受性丧失，可能为控制和操纵免疫细胞发育提供新的方法，以预防和/或治疗T细胞介导的疾病。

DESCRIPTION (provided by applicant): The immune system is a relevant target for analyzing how cells interpret the myriad of signals they receive through their surface receptors to make decisions regarding their fate and/or functional responses. Alterations in these processes contribute to the development of leukemias and other cancers as well as can predispose individuals to autoimmune diseases. This project focuses on how CD4 helper T cells are generated in the thymus. It is hypothesized that protein tyrosine phosphatase receptor kappa (PTPRk), previously shown to be responsible for the defective development of CD4 T cells in LEC rats, plays a central role in CD4 lineage commitment through modulation of Lck kinase activity. To test this hypothesis, aims include to: 1. Determine whether changes in the expression levels of PTPRk alter lineage commitment; 2. Show that Lck is a substrate for PTPRk; and 3. Identify the mechanisms that regulate T cell Receptor-mediated PTPRk expression during CD4 lineage commitment. PTPRk levels will be altered in T cell receptor Tg primary cells using genetic constructs, injected into recipient mice and then examined for lineage diversion. Effects on Lck activity will be tested by in vitro phosphatase assays as well as in vivo via pertinent cell lines. The expression pattern of PTPRk will be examined by quantitative RT-PCR on developmental intermediate populations. A loss of function approach will help to identify positive selection pathways affected by PTPRk. We propose a model where strong Lck signals induce PTPRK which then contributes to the sustained activation of Lck by dephosphorylating Lck at residue Y505. This positive feedback loop enables cells to commit to the CD4 lineage. Studies of T cell signaling proteins like PTPRK will expand our understanding of immune system development, especially with respect to the sequence of differentiation events that establish the functional program of helper T cells. A better understanding of T cell lineage decision and how changes in signaling between proteins may result in the formation of T cell-associated leukemias, lymphomas, and loss of tolerance leading to autoimmunity could suggest new ways to control and manipulate immune cell development for the purpose of preventing and/or treating T cell-mediated diseases.