Regulation of steroid hormone biosynthesis by the cytoskeleton.

Steroid hormones are synthesized in response to signaling cascades initiated by the trophic peptide hormones derived from the anterior pituitary. The mechanisms by which these peptide hormones regulate steroid hormone production are multifaceted and include controlling the transcription of steroidogenic genes, regulating cholesterol (substrate) uptake and transport, modulating steroidogenic enzyme activity, and controlling electron availability. Cytoskeletal polymers such as microfilaments and microtubules have also been implicated in regulating steroidogenesis. Of note, steroidogenesis is a multi-step process that occurs in two organelles, the endoplasmic reticulum (ER) and the mitochondrion. However, the precise mechanism by which substrates are delivered back and forth between these two organelles is unknown. In this review we will discuss the role of components of the cytoskeleton in conferring optimal steroidogenic potential. Finally, we present data that identifying a novel mechanism by which sphingosine-1-phosphate induces mitochondrial trafficking to promote steroidogenesis.