17α-Hydroxylase (CYP17) expression and subsequent androstenedione production in the human ovary.

Traditionally, in women, only the theca cells in the ovary and the zona reticularis layer of the adrenal cortex are believed to synthesize androgens. Interestingly, their neighboring cell layers, the granulosa cells and the zona glomerulosa cells, respectively, do not produce androgens. Recent literature has highlighted the role of the activator protein (AP-1) transcription factor, c-Fos, in the dynamics of this structural and functional relationship. Differential expression of c-Fos is believed to result in distinct patterns of steroidogenesis among these compartments in both the ovary and the adrenal glands. Clinically, deficient c-Fos levels have been implicated in the pathogenesis of polycystic ovary syndrome (PCOS). In this review, we discuss the pivotal role of c-Fos in controlling the expression of CYP17 and hence androgen production in various organ systems throughout the human body.