Control of interferon-τ gene expression by Ets-2

Expression of the multiple interferon-tau (IFN-tau) genes is restricted to embryonic trophectoderm of ruminant ungulate species for a few days in early pregnancy, The promoter regions of these genes are highly conserved. A proximal (bp -91 to -69) sequence has been implicated in controlling trophoblast-specific expression. Here it was used as a target for yeast one-hybrid screening of a day 13 conceptus cDNA library. Two transcription factors of the Ets family, Ets-2 and GABP alpha, were identified, consistent with the observation that active ovine IFN-tau genes contain a single 10-bp Ets motif (core: GGAA) in the proximal segment, whereas three known inactive ovine genes contain a mutated core motif (TGAA), Cotransfection of a promoter- (-126 to +50) luciferase reporter construct from an active gene (bovineIFN-tau 1; boIFNT1) and an Ets-2 expression plasmid in human JAr cells provided up to a 30-fold increase in reporter expression, whereas promoters from inactive genes were not transactivated. GABP alpha alone was ineffective and had only a approximate to 2-fold positive effect when coexpressed with its partner GABP beta, Other Ets-related transcription factors, which were not detected in the genetic screen, also provided a range of lesser transactivation effects. Coexpression of Ets-a and activated Ras Failed to transactivate the IFNT promoter greater than Ets-2 alone in JAr cells, The presence of Ets-2 in nuclei of embryonic trophectoderm was confirmed immunocytochemically, Together, these data suggest that Ets-2 plays a role in the transient expression of the nonvirally inducible IFNT genes.