The Journal of Immunology, Vol 146, Issue 3 1031-1036, Copyright © 1991 by American Association of Immunologists

ARTICLES

Expression of a novel nuclear protein in activated and in tat-I expressing T cells

A Bielinska, L Baier, N Hailat, JR Strahler, GJ Nabel and S Hanash
Howard Hughes Medical Institute, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109.

The intracellular events that occur in T lymphoid cells after activation or after infection with HIV-1 are not well defined. In the case of HIV-1 infection, it is unknown whether the tat-I gene, an essential gene for viral replication, affects host cell nuclear factors. Using two-dimensional PAGE, we have identified a novel nuclear protein, designated nuclear protein-28,000 (NP-28), which is induced in Jurkat T cells by stimulation with PMA and/or PHA or ionomycin. This nuclear protein has an apparent molecular mass of 28,000 Da and an isoelectric point of 4.6. Interestingly, Jurkat cells transfected with tat-I express higher levels of NP-28 constitutively, without added stimulation. Incubation of Jurkat cells expressing tat-I with PMA and/or PHA or ionomycin causes superinduction of NP-28. We have therefore identified a novel lymphoid nuclear protein induced by T cell activation that occurs in tat-I expressing cells in the absence of activating agents.