Nuclear factor-kappa B potently up-regulates the promoter activity of RANTES, a chemokine that blocks HIV infection

Abstract

The complex network of cytokines that are involved in inflammatory and immunoregulatory responses plays a critical role in the pathogenesis of HIV infection. RANTES (regulated upon activation, normal T cell expressed and secreted) is a cytokine that belongs to the beta-chemokine family; it is chemoattractant for CD4+/CD45RO T cells, it is produced by various cell types including CD8+ and CD4+ T cells as well as monocytes/macrophages, and has recently been shown to suppress replication of macrophage-tropic strains of HIV in CD4+ T cells. To investigate the molecular mechanisms of RANTES expression, the RANTES promoter region was analyzed by transient expression and gel-mobility shift assays. We demonstrate that: 1) RANTES promoter activity is up-regulated by PMA plus ionomycin, coexpression of the p65 subunit of nuclear factor (NF)-kappa B, the proinflammatory cytokines TNF-alpha and IL-1 beta, and the CD28 costimulatory pathway; 2) the RANTES promoter region contains four NF-kappa B binding sites at positions -30, -44, -213, and -579 relative to the transcription start site; 3) one site (-213) is an NF-AT (nuclear factor of activated T cells) binding site that also has weak affinity to NF-kappa B, and the most distal site (-579) also serves as a CD28-responsive element; and 4) mutation on any of those NF-kappa B sites or coexpression of I kappa B alpha (cytoplasmic inhibitor of NF-kappa B) markedly reduced the promoter activity. Thus, NF-kappa B, a potent transcriptional activator of HIV expression, is also involved in the expression of RANTES, a chemokine that blocks infection by macrophage-tropic strains of HIV.