Kappa B-specific DNA binding proteins: role in the regulation of human interleukin-2 gene expression.

Transcriptional activation of the human interleukin-2 (IL-2) gene, like induction of the IL-2 receptor alpha (IL-2R alpha) gene and the type 1 human immunodeficiency virus (HIV-1), is shown to be modulated by a kappa B-like enhancer element. Mutation of a kappa B core sequence identified in the IL-2 promoter (-206 to -195) partially inhibits both mitogen- and HTLV-I Tax-mediated activation of this transcription unit and blocks the specific binding of two inducible cellular factors. These kappa B-specific proteins (80 to 90 and 50 to 55 kilodaltons) similarly interact with the functional kappa B enhancer present in the IL-2R alpha promoter. These data suggest that these kappa B-specific proteins have a role in the coordinate regulation of this growth factor-growth factor receptor gene system that controls T cell proliferation.