Interaction of nuclear protein p140 with human immunodeficiency virus type 1 TAR RNA in mitogen-activated primary human T lymphocytes.

Several lines of evidence suggest that cellular proteins play a role during human immunodeficiency virus type 1 (HIV-1) Tat-mediated trans activation. A recent report from this laboratory has shown that a 140-kDa HeLa nuclear protein (p140) binds specifically to the lower stem region of the Tat response element, TAR RNA. Since HIV-1 trans activation is most efficient in proliferating T cells, we investigated the binding of p140 to TAR RNA in unstimulated and mitogen-activated, G1-phase primary T lymphocytes. TAR RNA/protein-binding activity was low in resting cells but increased significantly within 2 h of activation and remained elevated for at least 48 h. Corresponding increases in p140 protein levels were observed with most but not all donors, suggesting that an additional nuclear factor(s) may be required for efficient binding of this protein to TAR RNA in activated T cells.