Hormonal and molecular regulation of the cytochrome P450 aromatase gene expression in the ovary

Abstract

The cytochrome P450 aromatase (aromatase), encoded by the Cyp19a1 (Cyp19) gene, is the enzyme that converts androgens into estrogens in the ovarian granulosa cells. Estradiol-17β (estradiol), the most potent estrogen, is crucial for female and male fertility, as proved by the severe reproductive defects observed when its synthesis [1] or actions [2] are blocked. In the ovary, locally produced estradiol in concert with the pituitary gonadotropins is required for successful folliculogenesis and steroid production. Estradiol modulates the structure and function of female reproductive tissues, such as uterus and oviduct, and is required for the fluctuating patterns of biosynthetic and secretory activity of the gonadotropins in the pituitary gland, to generate the preovulatory surge of luteinizing hormone (LH), and for the cyclical variations in sexual female behavior. Therefore, the coordinated and cell-specific expression of the aromatase gene in the ovary is crucial for the normal progression of the menstrual/estrous cycle. This chapter reviews the molecular, cellular, and normal physiological mechanisms regulating the expression of the aromatase gene in the ovary. © 2009 Springer-Verlag US.