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淋巴细胞凋亡方面发挥关键作用，这是HIV介导的免疫功能障碍的主要致病特征。T细胞的凋亡也是一个生理过程，在T细胞的动态平衡和成熟过程中调节抗原受体的选择。我们假设gp120诱导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信号组件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说。此外，我们最近发现，TCR和趋化因子受体CXCR4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)、caspase-1和包含caspase招募结构域的丝氨酸/苏氨酸激酶(RIP2)介导。为了从机制上分析TCR组分和趋化因子受体CXCR4/CCR5如何调控gp120诱导的细胞凋亡，我们将致力于以下几个方面的研究：目的1)通过定义CD45的结构域，研究CD45与CXCR4/CCR5信号分子之间的相互作用，研究CD45信号在细胞凋亡中的作用。目的2)我们将对TCR介导的下游效应分子SLP-76进行结构和功能分析，SLP-76介导的是钙依赖的细胞凋亡途径。目的3)我们将分析AKT/HSP-70凋亡通路在诱导叉头转录因子中的作用，并将表征caspase-1的激活以及RIP2对其的调控。我们还在探索抑制gp120诱导的细胞凋亡的创新策略。在这方面，我们已经证明了一种新的蛋白质Sit，它与Robo受体结合并调节CXCR4功能，可以抑制gp120诱导的细胞凋亡。目的4)我们将确定Sit/Robo复合体中的哪些结构域调节已观察到的抗细胞凋亡作用。这些研究旨在确定T细胞丢失所涉及的凋亡信号分子和效应通路，从而为防治艾滋病的免疫缺陷提供新的治疗靶点。

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.