Foxo Transcription Factors Control Regulatory T Cell Development and Function

SummaryFoxo transcription factors integrate extrinsic signals to regulate cell division, differentiation and survival, and specific functions of lymphoid and myeloid cells. Here, we showed the absence of Foxo1 severely curtailed the development of Foxp3+ regulatory T (Treg) cells and those that developed were nonfunctional in vivo. The loss of function included diminished CTLA-4 receptor expression as the Ctla4 gene was a direct target of Foxo1. T cell-specific loss of Foxo1 resulted in exocrine pancreatitis, hind limb paralysis, multiorgan lymphocyte infiltration, anti-nuclear antibodies and expanded germinal centers. Foxo-mediated control over Treg cell specification was further revealed by the inability of TGF-β cytokine to suppress T-bet transcription factor in the absence of Foxo1, resulting in IFN-γ secretion. In addition, the absence of Foxo3 exacerbated the effects of the loss of Foxo1. Thus, Foxo transcription factors guide the contingencies of T cell differentiation and the specific functions of effector cell populations.

Graphical AbstractFigure optionsDownload full-size imageDownload high-quality image (205 K)Download as PowerPoint slideHighlights► Foxo1 controls Treg cell development and function ► Foxo1 directly controls expression of the Ctla4 gene ► In the absence of Foxo1, TGF-β causes T cells to assume a Th1 cell phenotype ► Double deficiency in Foxo1 and Foxo3 causes florid and pathologic autoimmunity