Calcium-dependent activation of nuclear factor regulated by interleukin 3/adenovirus E4 promoter-binding protein gene expression by calcineurin/nuclear factor of activated T cells and calcium/calmodulin-dependent protein kinase signaling.

An increase in the intracellular Ca(2+) concentration controls a diverse range of cell functions, including gene expression, apoptosis, adhesion, motility, and proliferation. We have investigated Ca(2+) regulation of gene expression in rat aortic smooth muscle cells. We found that the expression of nuclear factor regulated by interleukin 3 (NFIL3)/adenovirus E4 promoter-binding protein (E4BP4)/basic region/leucine zipper (bZIP) type of a transcription factor that has a very important function in cell survival, was activated by thapsigargin (TG). This activation was inhibited by chelation of extra- or intracellular Ca(2+), suggesting that the induction by TG was dependent on the elevation of Ca(2+). Specific inhibition of calcineurin or calcium/calmodulin-dependent protein kinase (CaM kinase) by chemical means impaired the TG-induced NFIL3/E4BP4 expression. Expression of dominant negative forms of calcineurin or nuclear factor of activated T cells (NFAT) inhibited the induction of NFIL3/E4BP4 mRNA by TG. These results suggest that intracellular Ca(2+) plays a critical role in regulating gene expression of NFIL3/E4BP4 by calcineurin/NFAT and CaM kinase signaling in vascular smooth muscle cells.