In vitro transcription faithfully reflecting T-cell activation requirements.

T-cell activation is a complex process mediated by cell membrane molecules including the T-cell antigen receptor (TCR), adhesive molecules, and cytokine receptors that collectively produce an increase in intracellular Ca2+, and activation of protein kinase C that initiate a genetic program resulting in immunologic function and irreversible differentiation. To understand how these cell membrane events are translated into a genetic regulatory cascade resulting in T-cell function, we have developed an in vitro transcription system, derived from Jurkat T-cells, which demonstrates inducible, cell-type-specific transcription following T-cell stimulation. Nuclear extracts from cells stimulated with phorbol 12-myristate 13-acetate and ionomycin, which activate protein kinase C and mimic physiological activation through the T-cell antigen receptor, transcribe an interleukin-2 (IL-2) enhancer (-326 to +24) template 5-fold more efficient than nuclear extracts from resting T-cells and severalfold more efficient than extracts from Jurkat cells treated with phorbol 12-myristate 13-acetate or ionomycin alone. Further results demonstrate that in vitro transcription of the IL-2 enhancer is T-cell specific since nuclear extracts from rat liver and stimulated HeLa cells are unable to induce IL-2 transcription. The activation-dependent, T-cell-specific in vitro transcription system described here should facilitate the dissection of signals that emanate from the T-cell surface resulting in IL-2 transcription and T-cell activation.