CCR7 REGULATION OF ERK5 PHOSPHORYLATION DURING AN IMMUNE RESPONSE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 C-C趋化因子受体7(CCR7)的主要功能是调节T淋巴细胞对淋巴结和淋巴结内的趋化作用。淋巴结中含有高水平的CCR7激动剂CCL21和CCL19。在正常情况下，CCR7+、NA+T淋巴细胞利用CCR7通过CCL21梯度向淋巴结迁移。在淋巴结中，NA‘ve T细胞与表达树突状细胞的CCL19上的第二个CCR7配体CCL19相遇。一旦与T淋巴细胞接触，树突状细胞就会产生来自病原体的多肽。不能识别同源树突状细胞的原始T淋巴细胞，离开淋巴结，回到循环中。如果检测到表达适当MHC/抗原结合的树突状细胞，T淋巴细胞/树突状细胞结合形成启动免疫反应。树突状细胞表面发现的CCL19的作用仍在确定中。更好地了解控制T淋巴细胞淋巴运输的受体的调节将为操纵T淋巴细胞的运动并最终控制宿主的免疫反应提供知识。淋巴细胞运输的几个步骤是可以理解的。首先，NA‘ve T淋巴细胞利用CCR7对CCL21趋化进入淋巴结。第二，EDG-1(内皮分化鞘氨醇-脂G蛋白偶联受体1)通过鞘氨醇1磷酸控制T淋巴细胞从淋巴结中退出。第三，Kruppel样因子2(KLF2)诱导EDG-1的表达，第四，KLF2的表达是由细胞外调节激酶5(ERK5)诱导的。然而，ERK5在免疫细胞功能中的作用尚不清楚。我们的初步数据表明，在人T细胞系和原代T细胞中，CCL19而不是CCL21激活CCR7可在1小时内诱导ERK5的磷酸化，并在24小时内上调KLF2的表达。此外，我们证明，在24-72小时内，用CCL19刺激这些细胞，而不用CCL21刺激，会导致HUT 78细胞向S1P迁移和EDG1表达增加。综上所述，这些结果提示CCR7/CCL19将T淋巴细胞的淋巴进入与EDG-1调节的淋巴出口联系在一起。我们今年的研究将集中在CCL19，而不是CCL21如何引发这种不同的反应。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary function of the C-C chemokine receptor 7 (CCR7) is to regulate chemotaxis of T lymphocytes to and within the lymph nodes. Lymph nodes contain high levels of CCR7 agonists, CCL21 and CCL19. Under normal conditions, CCR7+, na¿ve T lymphocytes use CCR7 to migrate to the lymph nodes via a CCL21 gradient. In lymph nodes, na¿ve T cells encounter the second CCR7 ligand, CCL19, on CCL19 expressing dendritic cells. Once in contact with the T lymphocyte, the dendritic cells present peptides from pathogens. Na¿ve T lymphocytes that fail to identify cognate dendritic cells, exit the lymph nodes and return to the circulation. If dendritic cells expressing the proper MHC/antigen combination are detected, T lymphocyte/dendritic cell conjugates form to initiate an immune response. The role of CCL19 found on the surface of the dendritic cells is still being determined. A better understanding of the regulation of receptors that control T lymphocyte lymph node traffic will provide knowledge to manipulate the movement of T lymphocytes and ultimately the immune response of the host. Several steps in the trafficking of lymphocytes are understood. First, na¿ve T lymphocytes use CCR7 to enter lymph nodes via chemotaxis to CCL21. Second, Edg-1 (Endothelial differentiation sphingo-lipid G protein-coupled receptor 1) controls T lymphocyte exit from the lymph nodes via sphingosine 1 phosphate. Third, Kruppel Like Factor 2 (KLF2) induces expression of Edg-1, and fourth the expression of KLF2 is induced by the extracellular regulated kinase 5 (ERK5). The role of ERK5, however, in immune cell function is unknown. Our preliminary data demonstrate that activation of CCR7 by CCL19 but not CCL21 in a human T cell line and in primary T cells induces phosphorylation of ERK5 within one hour and up-regulation of KLF2 within 24 hours. Furthermore, we demonstrate that stimulation of these cells with CCL19, but not with CCL21, over 24-72 hours, leads to increased migration of HuT 78 cells to S1P and expression of Edg1. Taken together, these results suggest that CCR7/CCL19 links lymph node entry of T lymphocytes to the Edg-1 regulated lymph node exit. Our studies this year will focus on how CCL19, but not CCL21 initiate such distinct responses.