CXCR4 CHEMOKINE RECEPTOR REGULATION OF ERK MAP KINASE

我们的长期目标是表征T淋巴细胞中趋化因子受体信号传导的分子机制和生物学影响。 为此，我们正在研究CXCR 4趋化因子受体在T细胞中的作用和功能机制。 CXCR 4刺激几种细胞类型的增殖和/或凋亡，缺乏CXCR 4或其配体SDF-1的突变小鼠死于发育缺陷。 此外，CXCR 4直接与人类免疫缺陷病毒-1（HIV-1）的gp 120糖蛋白结合，并与HIV-1结合CD 4一起，允许T淋巴细胞的病毒感染。 CXCR 4介导这些作用的分子机制知之甚少。 我们的初步研究结果表明，CXCR 4信号使用Gi蛋白激活T淋巴细胞中的ERK丝裂原活化蛋白（MAP）激酶。 ERK和其他MAP激酶响应于细胞表面受体的信号传导而磷酸化转录因子，从而允许生长因子和激素调节细胞生长和分化。我们的中心假设是，趋化因子受体使用不同的G蛋白，小GTP结合蛋白和激酶激活ERK的T淋巴细胞。 因此，我们的具体目标是：1）表征CXCR 4介导的MEK-1和ERK的刺激，2）表征CXCR 4与介导ERK活化的G蛋白的偶联，和3）表征lck和CD 4在CXCR 4活化ERK中的作用。 我们建议使用国家的最先进的分子技术结合正常的人类T细胞和T细胞模型细胞系，以表征CXCR 4介导的ERK激活的分子机制。 我们乐观地认为，该提案的成功完成将详细描述CXCR 4用于激活CXCR 4大量表达的重要细胞类型（T淋巴细胞）中ERK的分子机制。 由于ERK参与T淋巴细胞分化和免疫活化，这些研究的结果将为理解趋化因子控制免疫系统的发育和功能奠定基础。 此外，了解T淋巴细胞CXCR 4信号转导将为未来的研究提供理论框架，旨在了解艾滋病的病理生理学。

Our long-term goal is to characterize the molecular mechanisms and biological impact of chemokine receptor signaling in T lymphocytes. Toward this end, we are studying the role and mechanisms of function of the CXCR4 chemokine receptor in T cells. CXCR4 stimulates the proliferation and/or apoptosis of several cell types, and mutant mice lacking either CXCR4 or its ligand, SDF-1, die from developmental defects. In addition, CXCR4 binds directly to the gp120 glycoprotein of Human Immunodeficiency Virus-1 (HIV-1) and, together with HIV-1 binding to CD4, permits viral infection of T lymphocytes. The molecular mechanisms by which CXCR4 mediates these effects are poorly understood. Our preliminary results indicate that CXCR4 signaling uses a Gi protein to activate the ERK mitogen-activated protein (MAP) kinases in T lymphocytes. ERK and other MAP kinases phosphorylate transcription factors in response to signaling by cell-surface receptors, thereby allowing growth factors and hormones to regulate cell growth and differentiation. Our central hypothesis is that chemokine receptors use distinct G proteins, small GTP-binding proteins and kinases to activate ERK in T lymphocytes. Therefore, our specific aims are to: 1) characterize CXCR4-mediated stimulation of MEK-1 and ERK, 2) characterize CXCR4 coupling to G proteins that mediate ERK activation, and 3) characterize the role(s) of lck and CD4 in CXCR4 activation of ERK. We propose to use state-of-the-art molecular techniques in combination with normal human T cells and T cell model cell lines to characterize the molecular mechanisms of CXCR4-mediated ERK activation. We are optimistic that the successful completion of this proposal will characterize in detail the molecular mechanism(s) used by CXCR4 to activate ERK in an important cell type where CXCR4 is abundantly expressed: T lymphocytes. Since ERK participates in T lymphocyte differentiation and immune activation, the results of these studies will form a basis for understanding chemokine control of the immune system's development and function. In addition, understanding T lymphocyte CXCR4 signaling will provide the theoretical framework for future studies aimed at understanding the pathophysiology of AIDS.