NEGATIVE REGULATORY DOMAINS IN A TROPHOBLAST INTERFERON PROMOTER

A bovine trophoblast interferon (IFN-tau) gene promoter sequence (-450 to +26 bp relative to the transcription start site) led to expression of reporter gene (CAT) constructs transfected into L929 (murine fibro blast) or JAR (human choriocarcinoma) cells. Expression depended on th e presence of an exogenous (SV40) enhancer. Poly(I)(C) activated endog enous IFN production in L929 and JAR cells but had no consistent effec t on CAT expression. Similar results were obtained in L929 cells with inactivated Newcastle disease virus. There was no 'priming' effect of exogenous Type I IFN. Deletion mutants revealed sites exerting negativ e control on expression between - 338 and - 247 bp, and between - 150 and - 71 bp; these regions contained sequences resembling previously i dentified negative regulatory domains. In the absence of viral inducib ility it is proposed that negative regulation contributes towards the stringent control of expression characteristic of IFN-tau genes.