Foxp3 is a member of the forkhead/winged-helix family of transcriptional regulators and functions as the master regulator in the development and function of regulatory T cells. This article or section should be merged with suppressor T cell Regulatory T cells (also known as suppressor T cells) are characterised by virtue of their expression of the cell surface markers CD4 and CD25. ...

Human FOXP3 genes contain 11 coding exons. Exon-intron boundaries are identical across the coding regions of the mouse and human genes. By genomic sequence analysis, the FOXP3 gene maps to chromosome Xp11.23. The exon portion of a DNA strand encodes a specific portion of a protein. ... Diagram of the location of introns and exons within a gene. ... Figure 1: Chromosome. ...

FOXP3 gene is mutated in the X-linked syndrome of immunodysregulation, polyendocrinopathy, and enteropathy, (IPEX). These mutations were in the forkhead domain of FOXP3, indicating that the mutations may disrupt critical DNA interactions. In mice a Foxp3 mutation (a frameshift mutation that result in protein lacking the forkhead domain) is responsible for 'Scurfy', an X-linked recessive mouse mutant that results in lethality in hemizygous males 16 to 25 days after birth. These mice have overproliferation of CD4+ T lymphocytes, extensive multiorgan infiltration, and elevation of numerous cytokines. This phenotype is similar to lack expression of CTLA-4, TGF-beta, human disease IPEX, or deletion of the Foxp3 gene in mice. The pathology observed in scurfy mice seems to result from an inability to regulate properly CD4+ T-cell activity.

In mice overexpressing the Foxp3 gene, fewer T cells are observed. The remaining T cells have poor proliferative and cytolytic responses and poor IL2 production, although thymic development appears normal. Histologic analysis indicates that peripheral lymphoid organs, particularly lymph nodes lack cells.