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.