Control of the interferon-induced 68-kilodalton protein kinase by the HIV-1 tat gene product.

The tat-responsive region (TAR) of the human immunodeficiency virus-1 (HIV-1) exhibits a trans-inhibitory effect on translation in vitro by activating the interferon-induced 68-kilodalton protein kinase (p68 kinase). Productive infection by HIV-1 was shown to result in a significant decrease in the amount of cellular p68 kinase. The steady-state amount of p68 kinase was also reduced in interferon-treated HeLa cell lines stably expressing tat, as compared to the amount of the kinase in interferon-treated control HeLa cells. Thus, the potential translational inhibitory effects of the TAR RNA region mediated by activation of p68 kinase may be downregulated by tat during productive HIV-1 infection.