| Forkhead box (Fox) proteins are a family of evolutionarily conserved transcription factors containing a sequence known as Forkhead box or winged helix DNA binding domain. The human genome contains 43 Fox proteins that are divided into subfamilies. The FoxP subfamily has four members, FoxP1 to FoxP4, which are broadly expressed and play important roles in organ development, immune response, and cancer pathogenesis. The FoxP subfamily has several characteristics that are atypical among Fox proteins: their Forkhead domain is located at the carboxy-terminal region, and they contain motifs that promote homo- and heterodimerization. FoxP proteins usually function as transcriptional repressors. FoxP3 is crucial for the development of T cells with regulatory properties (Treg). Mutations in FoxP3 are associated with immunodeficiency polyendocrinopathy, enteropathy, and X-linked syndrome (IPEX), while overexpression in mice causes severe immunodeficiency. In addition, FoxP3 functions as a tumor suppressor in several types of cancer. |
