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Steroid biosynthesis
About: Steroid biosynthesis is a research topic. Over the lifetime, 1721 publications have been published within this topic receiving 58977 citations.
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TL;DR: The extensive development of smooth reticulum in fetal interstitial cells is consistent with experimental evidence that implicates these cells as the chief source of steroid hormones governing male reproductive tract differentiation.
Abstract: Smooth endoplasmic reticulum appears in interstitial cells and Sertoli cells of 22–24d testes of fetal guinea pigs before the beginning of morphological differentiation of the male reproductive tract at 29d (Price et al., '67), and before the appearance of demonstrable 3β-hydroxysteroid dehydrogenase, an enzyme important in steroid biosynthesis, in the interstitial cells at 29d (Ortiz et al., '66). This enzyme has not yet been demonstrated in the Sertoli cells.
The smooth reticulum of the interstitial cells increases in amount, filling the cells with tubules by 27d, and later forming some fenestrated cisternae which are occasionally seen in whorls. In Sertoli cells, the tubular reticulum shows signs of degeneration at 26d. After this time the cisternal endoplasmic reticulum in these cells increases in amount and by 45d is predominantly smooth-surfaced. Yet it is never as prominent as the smooth reticulum of the interstitial cells.
Scattered clusters of ribosomes or polyribosomes are seen on the surface of the tubular reticulum of these differentiating cells. These polyribosomes become more widely spaced as the smooth-surfaced areas increase and may be associated with the production of smooth membranes.
Smooth endoplasmic reticulum is known to play a role in the production of steroid hormones, and therefore the extensive development of smooth reticulum in fetal interstitial cells is consistent with experimental evidence that implicates these cells as the chief source of steroid hormones governing male reproductive tract differentiation.
117 citations
TL;DR: Sulfonation is a key reaction in the body's defense against injurious chemicals and may have a major function during early development since SULTs are highly expressed in the human fetus.
Abstract: Sulfonation has a major function in modulating the biological activities of a wide number of endogenous and foreign chemicals, including: drugs, toxic chemicals, hormones, and neurotransmitters. The activation as well as inactivation of many xenobiotics and endogenous compounds occurs via sulfonation. The process is catalyzed by members of the cytosolic sulfotransferase (SULT) superfamily consisting of at least ten functional genes in humans. The reaction in intact cells may be reversed by arylsulafatase present in the endoplasmic reticulum. Under physiological conditions, sulfonation is regulated, in part, by the supply of the co-substrate/donor molecule 3'-phosphadensoine-5-phosphosulfate (PAPS), and transport mechanisms by which sulfonated conjugates enter and leave cells. Variation in the response of individuals to certain drugs and toxic chemicals may be related to genetic polymorphisms documented to occur in each of the above pathways. Sulfonation has a major function in regulating the endocrine status of an individual by modulating the receptor activity of estrogens and androgens, steroid biosynthesis, and the metabolism of catecholamines and iodothyronines Sulfonation is a key reaction in the body's defense against injurious chemicals and may have a major function during early development since SULTs are highly expressed in the human fetus. As with many Phase I and Phase II reactions, sulfonation may also serve as the terminal step in activating certain dietary and environmental agents to very reactive toxic intermediates implicated in carcinogenesis.
117 citations
TL;DR: In vitro studies using isolated cells, mitochondria and submitochondrial fractions demonstrated that in steroid synthesizing cells, the peripheral-type benzodiazepine receptor (PBR) is an outer mitochondrial membrane protein involved in the regulation of cholesterol transport from the outer to the inner mitochondrial membrane, the rate-determining step in steroid biosynthesis.
117 citations
TL;DR: The study of streptomycete P450s involved in the biosynthesis of natural products has revealed their diverse roles in nature, expanded their catalytic repertoire, created structural and mechanistic paradigms, and exposed their potential for biomedical and biotechnological applications.
116 citations
TL;DR: RNA sequencing was performed in conjunction with physiological and morphological assessments to analyze the time-course of transcriptional and developmental responses in embryos/larvae of mahi-mahi exposed to WAF of weathered (slick) and source DWH oils, suggesting novel targets in addition to the heart may be involved in the developmental toxicity of DHW oil.
Abstract: The Deepwater Horizon (DWH) oil spill contaminated the spawning habitats for numerous commercially and ecologically important fishes. Exposure to the water accommodated fraction (WAF) of oil from the spill has been shown to cause cardiac toxicity during early developmental stages across fishes. To better understand the molecular events and explore new pathways responsible for toxicity, RNA sequencing was performed in conjunction with physiological and morphological assessments to analyze the time-course (24, 48, and 96 h post fertilization (hpf)) of transcriptional and developmental responses in embryos/larvae of mahi-mahi exposed to WAF of weathered (slick) and source DWH oils. Slick oil exposure induced more pronounced changes in gene expression over time than source oil exposure. Predominant transcriptomic responses included alteration of EIF2 signaling, steroid biosynthesis, ribosome biogenesis and activation of the cytochrome P450 pathway. At 96 hpf, slick oil exposure resulted in significant perturb...
116 citations