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 several focused cDNA chips containing approximately 3000 known human genes that are expressed and secreted by a variety of cell types including lymphoid cells and participate in cell growth, signal transduction, effector functions, CD molecules, metabolism and apoptosis. Initial studies using differential display analysis and commercial cDNA chips have demonstrated that T cells expressing either endogenous chemokine receptors or transfected chemokine receptors are induced to express a variety of known and unknown genes post ligand treatment. A number of genes have been identified including thioredoxin, CA150, flottlin, ferritin heavy chain, and various cytokines. These mRNA expression difference have since been verified by RT-PCR and Western blot analysis. 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 our customized human and murine microarray gene chips, we have examined the expression of over 6000 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 have been utilized to identify candidate genes for further study. We are currently confirming and characterizing several genes shown to be highly expressed after stimulation with SDF-1, MCP-1, MIP-2, MIP-3, RANTES, IP-10, IL-8, gp120 and HIV-1 virus. A greater understanding of the transcriptional signals differentially induced by the ligation of various chemokine receptors may provide a means to dissect the pathways by which these chemoattractants induce cell migration and activation as well as any host transcriptional signals important in HIV entry and replication.
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