Calcium–NFAT transcriptional signalling in T cell activation and T cell exhaustion

A cornerstone of the adaptive immune response is the T cell receptor (TcR)–calcium–calcineurin signalling pathway leading to T cell activation. The ‘nuclear factor of activated T cells’ proteins NFAT1, NFAT2, and NFAT4 are transcription factors that promote expression of a panel of genes required for activation. It has become apparent that these same NFAT transcription factors underlie an alternative transcriptional program in T cells that serves to limit the immune response. This duality in NFAT transcriptional functions raises the possibility that NFAT transcriptional complexes could be targeted therapeutically to alter the relative strength of the effector and alternative transcriptional programs, thereby modulating immune responses.