Gonadal transactivation of STARD1, CYP11A1 and HSD3B.

The steroidogenic acute regulatory protein, cytochrome P450 cholesterol side-chain cleavage enzyme and specific 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerases initiate the essential process of steroidogenesis in the gonads. Testicular and ovarian expression of their respective genes, STARD1, CYP11A1 and gonadal HSD3B, is primarily controlled by gonadotropins with contributions by various growth factors. Gonadotropins through their receptors switch on cyclic AMP signaling pathways that recruit NR5A, GATA and often CREB, NR4A, or Sp1 transcription factors to regulatory regions of each gene's promoter to elicit transcription. The specific combination of transcription factors involved depends on the cellular context. In this review, we summarize current understanding of the factors that control transactivation of the STARD1, CYP11A1 and gonadal HSD3B genes in Leydig cells in the testis and the theca, differentiating granulosa and luteal cells in the ovary.