Besides chemotaxis, C-X-C and C-C chemokines function as mediators in T-cell activation and in many lymphocyte biological responses. Detailed information about downstream signaling pathways is necessary to understand the role of chemokines in normal physiology and inflammation. We have built a focused cDNA chips containing approximately 2500 known genes that are expressed and secreted by lymphoid cells and participate in their growth, signal transduction, and apoptosis. In initial experiments using differential display analysis and commercial cDNA chips, Jurkat T cells and purified human T cells, expressing either endogenous chemokine receptors or transfected chemokine receptors, were utilized to examine the ability of chemokine ligands to induce unique mRNA expression. Using this approach, we have observed significant differences in gene expression by cells treated by different ligands that bind the same chemokine receptor. Additional studies are underway examining the ability of various HIV-1 viral isolates, gp120 proteins, cytokines, and chemokines to directly induce gene expression in young and old human lymphocytes and neuronal cells. We believe that active transcriptional signals through CD4 and/or chemokine receptor molecules are required for optimal HIV-1 infectivity and propagation as well as for normal lymphocyte adhesion and migration. Using differential display analysis and microarray gene chips, we are examining the expression of known and unknown genes induced post chemokine receptor ligation or viral infection. We believe that the identification and examination of induced or suppressed genes will not only provide insight into HIV pathogenesis but may also elucidate the molecular mechanisms of inflammation and the various signaling defects observed in aged lymphocytes. Both focused and 15K arrays are being utilized to identify candidate genes for further study.
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