DOMINANT-NEGATIVE MUTANT OF C-JUN INHIBITS NF-AT TRANSCRIPTIONAL ACTIVITY AND PREVENTS IL-2 GENE-TRANSCRIPTION

Expression of the transcription complex AP-1, composed of Jun and Fos family members, can be induced by a variety of stimuli. In lymphocytes , AP-1 transcriptional activity increases after TCR ligation and plays an important role in T cell activation events such as lymphokine secr etion. To explore the requirements for AP-1 in IL-2 production, the AP -1 complex was targeted with a dominant negative mutant c-Jun protein, TAM-67, from which the transactivation domain has been deleted. In tr ansient transfections of Jurkat cells, TAM-67 efficiently inhibited en dogenous AP-1 transcriptional activity and blocked the activity of a r eporter construct containing the 5' regulatory region of the IL-2 gene . TAM-67 also inhibited the transcriptional activity of nuclear factor -AT (NF-AT), whereas the NF-kappa B, NF-IL-2A, and the proximal TRE-li ke sites were relatively unaffected. The use of this dominant negative transcription factor suggests that: 1) transactivation-defective nucl ear factors represent a novel approach to study the functional consequ ences of nuclear protein interactions on gene transcription; 2) the pr oximal TRE-like site from the IL-2 promoter is different from the cons ensus TRE; and 3) AP-1 plays an important role in the transcriptional activation mediated by the NF-AT binding complex.