FIG. 1.

JNK1 inhibits NFAT activity in T cells. (A) Activation of JNK1 inhibits NFATc1 nuclear localization. Jurkat T cells were transfected without (empty expression vector; Control) and with MKK7 plus JNK1 (JNK). After 16 h, the cells were stimulated without (−) and with (+) ionomycin (I; 2 μM) plus PMA (P; 100 nM) for 6 h. Nuclear extracts were isolated (14), and NFATc1 was examined by protein immunoblot analysis using monoclonal antibody 7A6 (Affinity Bioreagents). Similar data were obtained in three independent experiments. (B) Activated JNK inhibits NFAT transcription activity. Jurkat T cells were transfected with an IL-4 promoter reporter gene (firefly luciferase) plasmid together without (Control) and with MKK7 plus JNK1 (JNK) or dnNFAT. Transfection efficiency was monitored by measurement of Renilla luciferase activity. The cells were stimulated without (□) and with (■) ionomycin (2 μM) plus PMA (100 nM) for 6 h. The data are presented as fold activation by in treated compared to untreated cells (mean ± standard deviation; n = 4).