The calcineurin-regulated transcription factor, nuclear factor of activated T cells (NFAT), controls many aspects of T cell function. Here, we demonstrate that the calcineurin/NFAT pathway negatively regulates the expression of cyclin-dependent kinase 4 (CDK4). A canonical NFAT binding site was identified and found to be sensitive to calcium signals, FK506/CsA, and histone deacetylase activity and to not require AP-1. Ectopic expression of NFATc2 inhibited the basal activity of the human CDK4 promoter. Additionally, both calcineurin Aalpha(-/-) and NFATc2(-/-) mice had elevated protein levels of CDK4, confirming a negative regulatory role for the calcineurin/NFAT pathway. This pathway may thus regulate the expression of CDK4 at the transcriptional level and control how cells re-enter a resting, nonproliferative state.
