The acute regulation of mineralocorticoid biosynthesis: Scenarios for the StAR system

The zona glomerulosa cell of the adrenal cortex produces mineralocorticoids in response to physiological stimuli (angiotensin II and extracellular K+) activating the Ca2+ messenger system. The mechanisms underlying the genera tion of the Ca2+ signal have been analyzed extensively and recent developme nts have contributed to bridging the gap between intracellular signals and activation of the biological function. This article summarizes the current knowledge on the intracellular targets of the Ca2+ messenger, obtained main ly in bovine glomerulosa cells. Ca2+ appears to exert a dual effect, both a t the intramitochondrial level and at the nuclear level, where it activates steroidogenic acute regulatory protein (StAR) gene transcription.