The Ets transcription factor ERM is Th1-specific and induced by IL-12 through a Stat4-dependent pathway

Interleukin 12 (IL-12)-induced T helper 1 (Th1) development requires Stat4 activation. However, antigen-activated Th1 cells can produce interferon gam ma (IFN-gamma) independently of IL-12 and Stat4 activation. Thus, in differ entiated Th1 cells, factors regulated by IL-12 and Stat4 may be involved in IFN-gamma production. Using subtractive cloning, we identified ERM, an Ets transcription factor, to be a Th1-specific, IL-12-induced gene. IL-12-indu ction of ERM occurred in wild-type and Stat1-deficient, but not Stat4-defic ient, T cells, suggesting ERM is Stat4-inducible. Retroviral expression of ERM did not restore IFN-gamma production in Stat4-deficient T cells, but au gmented IFN-gamma expression in Stat4-heterozygous T cells. Ets factors fre quently regulate transcription via cooperative interactions with other tran scription factors, and ERM has been reported to cooperate with c-Jun, Howev er, in the absence of other transcription factors, ERM augmented expression of an IFN-y reporter by only 2-fold. Thus, determining the requirement for ERM in Th1 development likely will require gene targeting.