Epigenetic regulation of the expression of genes involved in steroid hormone biosynthesis and action.

Steroid hormones participate in organ development, reproduction, body homeostasis, and stress responses. The steroid machinery is expressed in a development- and tissue-specific manner, with the expression of these factors being tightly regulated by an array of transcription factors (TFs). Epigenetics provides an additional layer of gene regulation through DNA methylation and histone tail modifications. Evidence of epigenetic regulation of key steroidogenic enzymes is increasing, though this does not seem to be a predominant regulatory pathway. Steroid hormones exert their action in target tissues through steroid nuclear receptors belonging to the NR3A and NR3C families. Nuclear receptor expression levels and post-translational modifications regulate their function and dictate their sensitivity to steroid ligands. Nuclear receptors and TFs are more likely to be epigenetically regulated than proteins involved in steroidogenesis and have secondary impact on the expression of these steroidogenic enzymes. Here we review evidence for epigenetic regulation of enzymes, transcription factors, and nuclear receptors related to steroid biogenesis and action.