Calcium-dependent activation of TNF family gene expression by Ca2+ calmodulin kinase type IV Gr and calcineurin

CD40 ligand (L), FasL, and TNF-alpha are members of the TNF family of cytok ines. All are expressed by T lymphocytes shortly after activation but have distinct effector functions, Transcription of these genes can be induced by stimulation of T cells by calcium ionophore alone and requires the calcine urin-dependent transcription factor NF of activated T cells. We have examin ed a second calcium-dependent signaling pathway, mediated by calcium/calmod ulin dependent kinase IV (CaMKIV) in transcriptional activation of TNF fami ly genes. In reporter gene assays using constructs driven by the promoters of human CD40L, FasL, or TNF-alpha along with vectors expressing constituti vely active CaMKIV and calcineurin, we have demonstrated that each promoter is activated by calcineurin and CaMKIV in a synergistic fashion. Furthermo re, specific inhibition of CaMKIV by chemical means and by a dominant negat ive mutant of CaMKIV impairs the ionomycin-induced activity of all three pr omoters as well as protein expression of CD40L and TNF-alpha. Our results i ndicate that activation of gene expression by calcineurin and CaMKIV is com mon to members of the TNF cytokine family.