Mitogen stimulation of T-cells increases c-Fos and c-Jun protein levels, AP-1 binding and AP-1 transcriptional activity.
We have analysed the effect of mitogenic lectins on c-Fos and c-Jun protein levels as well as on activator protein-1 (AP-1) binding and enhancer activity in Jurkat T-cells. Both c-Fos and c-Jun protein levels were increased after Con A and PHA stimulation. Since T-cell stimulation increases both intracellular Ca2+ and cAMP levels and activates protein kinase C (PKC), the possible involvement of these intracellular messengers in c-Fos and c-Jun induction was tested. PMA, which directly activates PKC, mimicked the effect of the lectins on c-Fos and c-Jun, but elevation of either intracellular Ca2+ or cAMP levels had little or no effect. The mitogen-induced increase of c-Fos and c-Jun immunoreactivity was inhibited by H-7, a kinase inhibitor with relatively high specificity for PKC, and less efficiently by H-8, a structurally related kinase inhibitor less active on PKC, but more active on cyclic nucleotide-dependent kinases. Con A stimulation was found to increase both binding of AP-1 to the AP-1 consensus sequence, TRE, and AP-1 enhancer activity, in Jurkat cells. PMA was also found to increase the AP-1 enhancer activity, whereas elevation of Ca2+ or cAMP had only minor effects. We conclude that stimulation with mitogenic lectins is sufficient to increase both c-Fos and c-Jun protein levels, AP-1 binding and AP-1 enhancer activity in Jurkat cells and that they act via mechanisms that could involve the activation of PKC.
Kvanta
A
A
Department of Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Kontny
E
E
Jondal
M
M
Okret
S
S
Fredholm
B B
BB
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D003208:Concanavalin A / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D037102:Lectins; D010703:Phorbol Esters; D010835:Phytohemagglutinins; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis*; D016755:Proto-Oncogene Proteins c-jun / Q000032:analysis*; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D007546:Isoquinolines; D037102:Lectins; D010703:Phorbol Esters; D010835:Phytohemagglutinins; D010879:Piperazines; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D003208:Concanavalin A; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; D011493:Protein Kinase C