Octamer transcription factors up-regulate the expression of CCR5, a coreceptor for HIV-1 entry

T cell activation can induce expression of CCR5, a major coreceptor for mac rophage-tropic (R5) human immunodeficiency virus type 1 (HIV-1). Here we re port that overexpression of the Oct-2 transcription factor and octamer coac tivator BOB.1/OBF/OCA-B, both of which are induced in T cells following T c ell receptor signaling, synergistically up-regulates CCR5 promoter activity via interaction with an octamer motif on the promoter. We also show that t he octamer transcription factors can increase cell surface expression of CC R5 and fusogenicity of the cells with R5 HIV-1 Env. These results suggest t hat octamer transcription factors may play a critical role in the induction of CCR5 expression on, and thereby susceptibility to, R5 HIV-1 of T cells following antigenic stimulation.