Abstract
The fundamental framework of steroidogenesis is similar across steroidogenic cells, especially in initial mitochondrial steps. For instance, the START domain containing protein-mediated cholesterol transport to the mitochondria, and its conversion to pregnenolone by the enzyme P450scc, is conserved across steroidogenic cells. The enzyme P450scc localizes to the inner mitochondrial membrane, which makes the mitochondria essential for steroidogenesis. Despite this commonality, mitochondrial structure, number, and dynamics vary substantially between different steroidogenic cell types, indicating implications beyond pregnenolone biosynthesis. This review aims to focus on the growing roles of mitochondria, autophagy and lipophagy in cholesterol uptake, trafficking and homeostasis in steroidogenic cells and consequently in steroidogenesis. We will focus on these aspects in the context of the physiological need for different steroid hormones and cell-intrinsic inherent features in different steroidogenic cell types beyond mitochondria as a mere site for the beginning of steroidogenesis. The overall goal is to provide an authentic and comprehensive review on the expanding role of steroidogenic cell-intrinsic processes in cholesterol homeostasis and steroidogenesis, and to bring attention to the scientific community working in this field on these promising advancements. Moreover, we will discuss a novel mitochondrial player, prohibitin, and its potential role in steroidogenic mitochondria and cells, and consequently, in steroidogenesis.
Highlights
Steroid hormones are an important class of regulatory molecules, which are synthesized mainly in the adrenal glands, the ovary, and the testis, in response to steroidogenic stimuli, and regulate growth and drive a variety of physiological processes, such as reproduction and metabolism [1]
The importance of steroid hormones are evident from their wide-ranging essential functions in the body physiology, including carbohydrate metabolism, stress response, and in the regulation of salt balance pertaining to the maintenance of blood pressure by adrenal corticoids to the role of sex steroid hormones in males and females in the development of secondary sex characteristics, maintenance of reproductive functions, and perpetuation of life, as well as an essential role of progesterone for a successful pregnancy [2]
The first step in the biosynthesis of steroid hormones is the enzymatic cleavage of a six-carbon unit side chain of cholesterol molecule by the 20–22 desmolase/lyase activity of the cytochrome P450 side chain cleavage (P450scc) enzyme system located in the inner mitochondrial membrane (IMM) [3,4]
Summary
Steroid hormones are an important class of regulatory molecules, which are synthesized mainly in the adrenal glands, the ovary, and the testis, in response to steroidogenic stimuli, and regulate growth and drive a variety of physiological processes, such as reproduction and metabolism [1]. The steroid hormones are not stored in secretory vesicles like peptide hormones, but released into the blood upon their biosynthesis [8] This instant set-up between the biosynthesis and release of steroid hormones is expected to require an arrangement to maintain the readily available cholesterol pool within steroidogenic cells, because the cholescontents of mitochondrial membranes, especially the IMM, steroidogenesis begins, is terol contents of mitochondrial membranes, especially the where. Wetohave two interconnected goals: first, to discuss importance various processes involved maintain a readily available pool of cholesthe of various involved to maintain a readily available pool of terolimportance for the varying need of processes steroidogenic demands, and second, to review the growing cholesterol for the varying needand of lipophagy, steroidogenic and second, review the role of mitochondria, autophagy, and demands, other related activities in to a steroidogrowing of mitochondria, and lipophagy, and other related activities genic cellrole type-specific manner autophagy, to meet the diverse physiological demand of each steroidin a steroidogenic cell 2). We will not discuss genic cellsand butcellular instead events will focus on accruingsequestering evidence related autophagy, signaling in cholesterol andto trafficking in lipophagy, steroidogenic and the mitochondrial dynamics involved in handling the cholesterol pool in the cytocells but instead will focus on accruing evidence related to autophagy, lipophagy, and the plasm of steroidogenic cells, and highlight any pertinent questionspool that in may in this of mitochondrial dynamics involved in handling the cholesterol thearise cytoplasm exploration. cells, and highlight any pertinent questions that may arise in this exploration
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
