Transcription factors as regulators of steroidogenic P-450 enzymes

Steroid hormones are essential for normal sexual development, accommodation to stress, and regulation of fluid and electrolyte balance. Biosynthesis o f these different classes of steroids and its appropriate regulation requir es the precisely controlled expression of six different cytochrome P-450 en zymes and two hydroxysteroid dehydrogenases in different tissues. The molec ular mechanism of the tissue-specific and pituitary hormone-regulated expre ssion of the genes encoding P-450 enzymes in the steroidogenic tissues is t he central problem of long-term regulation of steroidogenesis. Orphan membe rs of the nuclear receptor superfamily play an important role in mediating transcriptional regulation of several steroid hydroxylase genes. Two of the se transcription factors, steroidogenic factor-1 (SF-1) and DAX-1, will be reviewed here in detail.