Activation and deactivation of gene expression by Ca2+/calcineurin-NFAT-mediated signaling.

Ca2+/calcineurin-NFAT-mediated signaling pathways are involved in diverse cellular reactions by regulating gene expression either positively or negatively. The transcriptional activity of NFAT proteins can be either activating or deactivating depending on which binding partners are involved. Interaction of NFAT with AP-1 turns on the genes involved in active immune responses, while NFAT without cooperative binding of AP-1 turns on a T cell anergy program and blocks T cell activation and proliferation. In addition, interaction of NFAT with histone deacetylase (HDAC) proteins induces gene silencing. In this review we focus on the dual function, activator or deactivator, of NFAT and the binding partners that determine the role of NFAT in gene expression.