27 April 2018 Current knowledge on the acute regulation of steroidogenesis
Vimal Selvaraj, Douglas M. Stocco, Barbara J. Clark
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How rapid induction of steroid hormone biosynthesis occurs in response to trophic hormone stimulation of steroidogenic cells has been a subject of intensive investigation for approximately six decades. A key observation made very early was that acute regulation of steroid biosynthesis required swift and timely synthesis of a new protein whose role appeared to be involved in the delivery of the substrate for all steroid hormones, cholesterol, from the outer to the inner mitochondrial membrane where the process of steroidogenesis begins. It was quickly learned that this transfer of cholesterol to the inner mitochondrial membrane was the regulated and ratelimiting step in steroidogenesis. Following this observation, the quest for this putative regulator protein(s) began in earnest in the late 1950s. This review provides a history of this quest, the candidate proteins that arose over the years and facts surrounding their rise or decline. Only two have persisted—translocator protein (TSPO) and the steroidogenic acute regulatory protein (StAR). We present a detailed summary of the work that has been published for each of these two proteins, the specific data that has appeared in support of their role in cholesterol transport and steroidogenesis, and the ensuing observations that have arisen in recent years that have refuted the role of TSPO in this process. We believe that the only viable candidate that has been shown to be indispensable is the StAR protein. Lastly, we provide our view on what may be the most important questions concerning the acute regulation of steroidogenesis that need to be asked in future.

Summary Sentence

The acute regulation of steroidogenesis in the adrenal and gonads is controlled by cholesterol transfer into the mitochondria and this review covers two decades of research that has demonstrated StAR is indispensable for this process.

© The Author(s) 2018. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
Vimal Selvaraj, Douglas M. Stocco, and Barbara J. Clark "Current knowledge on the acute regulation of steroidogenesis," Biology of Reproduction 99(1), 13-26, (27 April 2018). https://doi.org/10.1093/biolre/ioy102
Received: 16 November 2017; Accepted: 26 April 2018; Published: 27 April 2018
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