Cloning and characterization of a novel SF-1 interacting protein

Steroidogenic Factor-1 is a member of the orphan nuclear receptor family that acts as a transcription factor to regulate transcription of several genes involved in adrenal and gonadal development and steroidogenesis. A yeast two-hybrid screen with SF-1 as a bait was initiated to search for proteins that interact with SF-1 and further regulate transcription of the SF-1 target genes. An unknown sequence was isolated from a human testis library in this yeast two-hybrid screen. The full-length cDNA was then cloned from a lambda library, and a BLAST search revealed that this gene is localized to the human chromosome 19 and contains 9 exons. The predicted protein contains 615 amino acids and five C2H2 zinc fingers. The interaction with SF-1 is dependent on the activation function-2 domain (AF-2) of SF-1. Northern hybridization and In situ hybridization demonstrated coexpression with SF-1 in the testis and the adrenals. Transfection experiments in adrenal cortical Y1 cells indicate that the possible function of this novel SF-1 interacting protein is repression of the SF-1 target genes Cytochrome P450 steroid hydroxylase-17a (CYP17) and the Cholesterol side chain cleavage cytochrome P450 (CYP11A). ________________________________________