Eos Mediates Foxp3-Dependent Gene Silencing in CD4 + Regulatory T Cells

Abstract

T reg Responses to Eos CD4 + regulatory T cells (T regs ) are critical for keeping our immune system in check: They prevent immune responses from getting out of hand and keep autoimmunity at bay. By activating the expression of some genes and turning off expression of others, the master regulatory transcription factor of T regs , Foxp3, endows these cells with the appropriate gene expression program to mediate their suppressive effects. Pan et al. (p. 1142 , published online 20 August) now demonstrate that the transcription factor Eos is selectively required for Foxp3-mediated gene suppression in mice. Genes normally suppressed by Foxp3 in T regs remained “on” when Eos expression was suppressed, whereas genes activated by Foxp3 were unaffected. T reg function was also affected by Eos suppression. With half their genetic program disrupted, these cells resembled an intermediate between T regs and conventional CD4 + T cells—unable to suppress immune responses properly and partially responsive to T cell–activating stimulation.