THE ORPHAN RECEPTOR SF-1 BINDS TO THE COUP-LIKE ELEMENT IN THE PROMOTER OF THE ACTIVELY TRANSCRIBED OXYTOCIN GENE

The factors regulating oxytocin expression have not yet been character ized in detail. Although direct control by ligand-dependent binding of nuclear hormone receptors to the oxytocin promoter has been suggested , the presence of these receptors in the tissues expressing oxytocin h as not been shown consistently. We have analyzed nuclear proteins from preovulatory bovine granulosa cells and corpus luteum, tissues active ly expressing the oxytocin gene, and describe here the characterizatio n of a tissue-specific factor binding to the conserved element in the oxytocin promoter that has been implicated in the control of this gene . This factor is the bovine homologue of SF-I, an orphan receptor expr essed specifically in steroidogenic tissues. It is suggested that SF-1 binds to the oxytocin promoter in vivo and is involved in control of oxytocin gene expression possibly by interaction with other factors.