Role of Chemokine & T-Cell Receptors in HIV Pathogenesis

描述（由申请人提供）：HIV包膜蛋白gp120在触发T淋巴细胞凋亡中起关键作用，T淋巴细胞凋亡是HIV介导的免疫功能障碍的主要致病特征。T细胞凋亡也是在T细胞的稳态和成熟期间调节抗原受体库选择的生理过程。我们假设gp120诱导的T细胞受体（TCR）和趋化因子受体信号通路之间的串扰导致细胞凋亡。我们关于TCR信号传导组分CD45和SLP-76在HIV-gpl20诱导的细胞凋亡中的作用的初步数据支持这一假设。此外，我们最近发现TCR和趋化因子受体CXCR 4之间的相互作用通过一种新的机制调节细胞凋亡，该机制由AKT/蛋白激酶B（PKB）、热休克蛋白-70（HSP-70）、半胱天冬酶-1和RIP2（含半胱天冬酶募集结构域的丝氨酸/苏氨酸激酶）介导。为了分析TCR组分和趋化因子受体CXCR4/CCR5如何调节gp120诱导的细胞凋亡，我们将追求以下具体目标：目的1）我们将通过定义CD45的结构域和表征负责细胞凋亡的CD45信号传导来评估CD45和CXCR4/CCR5信号传导分子之间的相互作用。目的2）我们将对TCR介导的下游效应子SLP-76进行结构和功能分析，该效应子介导Ca 2+依赖性凋亡途径。目的3）分析AKT/HSP-70凋亡通路中可能导致叉头转录因子诱导的作用，并表征caspase-1的激活及其受RIP2的调节。我们也在探索创新的策略来抑制gp120诱导的细胞凋亡。在这方面，我们已经表明，一种新的蛋白质，Slit，它结合到Robo受体和调节CXCR4功能可以抑制gp120诱导的细胞凋亡。目的4）我们将鉴定Slit/Robo复合物中的哪些结构域调节所观察到的抗凋亡作用。这些研究旨在鉴定参与T细胞损失的凋亡信号分子和效应通路，从而提供新的治疗靶点以对抗艾滋病中的免疫缺陷。

DESCRIPTION (provided by applicant): The HIV-envelope protein gp120 plays a critical role in triggering the apoptosis of T-lymphocytes, which is a central pathogenic feature of HIV-mediated immune dysfunction. T-cell apoptosis is also a physiological process that regulates antigen receptor repertoire selection during homeostasis and the maturation of T- cells. We hypothesize that gp120-induced cross-talk between T-cell receptor (TCR) and chemokine receptor signaling pathways leads to apoptosis. Our preliminary data on the role of the TCR signaling components CD45 and SLP-76 in HIV-gpl20-induced apoptosis support this hypothesis. In addition, we have recently shown that cross-talk between TCR and chemokine receptor CXCR4 regulates apoptosis via a novel mechanism that is mediated by AKT/Protein Kinase B (PKB), heat shock protein-70 (HSP-70), caspase-1 and RIP2 (caspase recruitment domain-containing serine/threonine kinase). To analyze mechanistically how the TCR components and chemokine receptors CXCR4/CCR5 regulate gp120-induced apoptosis, we will pursue the following specific aims: Aim 1) we will assess the interaction between CD45 and CXCR4/CCR5 signaling molecules by defining the domain of CD45 and characterizing the CD45 signaling responsible for apoptosis. Aim 2) we will perform structural and functional analyses of the TCR-mediated downstream effector SLP-76 that mediates Ca2+dependent apoptotic pathways. Aim 3) we will analyze the role of the AKT/HSP-70 apoptotic pathway that may lead to the induction of forkhead transcription factors, and will characterize the activation of caspase-1 and its regulation by RIP2. We are also exploring innovative strategies to inhibit gp120-induced apoptosis. In this regard, we have shown that a novel protein, Slit, which binds to the Robo receptor and modulates CXCR4 function can inhibit gp120-induced apoptosis. Aim 4) we will identify which domains in the Slit/Robo complex regulate the observed anti-apoptotic effects. These studies are designed to identify apoptotic signaling molecules and effector pathways involved in T-cell loss, and thus to provide novel therapeutic targets to combat immune deficiency in AIDS.