NFAT (nuclear factor of activated T cells) is a family of transcription factors that play a crucial role in the regulation of gene expression in immune cells, particularly T cells. These proteins are vital components of the signaling pathway that facilitates the activation and differentiation of T cells, which are key players in adaptive immune responses.
The NFAT family consists of several isoforms, including NFAT1 (also known as NFATc2 or NFATp), NFAT2 (or NFATc1 or NFATc), NFAT3 (or NFATc4 or NFATx), and NFAT4 (or NFATc3). They are typically found in an inactive state in the cytoplasm of resting T cells. Upon stimulation, such as through the engagement of T cell receptors by antigens, calcium signaling is initiated, leading to the activation of the phosphatase calcineurin. Activated calcineurin dephosphorylates NFAT, allowing its translocation into the nucleus where it binds to specific DNA sequences called NFAT response elements (NREs) found in the promoters of target genes.
The binding of NFAT to NREs promotes the expression of genes involved in T cell activation, proliferation, and effector functions, thereby modulating immune responses. NFAT regulates the production of various cytokines, such as interleukin-2 (IL-2) and interferon-gamma (IFN-γ), which are crucial for immune cell communication and coordination. Additionally, NFAT also participates in the development and function of other immune cells, including B cells and natural killer cells.
Overall, NFAT transcription factors serve as vital mediators of immune responses, acting as key regulators of gene expression in T cells and other immune cells.
