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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 results show that, when the cells are placed in medium devoid of extracellular cholesterol and acutely stimulated with human choriogonadotropin, most of the cholesterol used for steroid biosynthesis is derived from intracellular stores.
92 citations
TL;DR: This is the first report describing the transcriptome of human sebocytes and its modification by a cocktail of hormones administered in age‐specific levels and provides an in vitro model system, which approximates some of the hormone‐dependent changes in gene transcription that occur during aging in humans.
Abstract: The importance of hormones in endogenous aging has been displayed by recent studies performed on animal models and humans. To decipher the molecular mechanisms involved in aging we maintained human sebocytes at defined hormone-substituted conditions that corresponded to average serum levels of females from 20 (f20) to 60 (f60) years of age. The corresponding hormone receptor expression was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR), Western blotting and immunocytochemistry. Cells at f60 produced significantly lower lipids than at f20. Increased mRNA and protein levels of c-Myc and increased protein levels of FN1, which have been associated with aging, were detected in SZ95 sebocytes at f60 compared to those detected at f20 after 5 days of treatment. Expression profiling employing a cDNA microarray composed of 15 529 cDNAs identified 899 genes with altered expression levels at f20 vs. f60. Confirmation of gene regulation was performed by real-time RT-PCR. The functional annotation of these genes according to the Gene Ontology identified pathways related to mitochondrial function, oxidative stress, ubiquitin-mediated proteolysis, cell cycle, immune responses, steroid biosynthesis and phospholipid degradation - all hallmarks of aging. Twenty-five genes in common with those identified in aging kidneys and several genes involved in neurodegenerative diseases were also detected. This is the first report describing the transcriptome of human sebocytes and its modification by a cocktail of hormones administered in age-specific levels and provides an in vitro model system, which approximates some of the hormone-dependent changes in gene transcription that occur during aging in humans.
92 citations
TL;DR: It is demonstrated that steroid biosynthesis is a microaerobic process, enabled by dissolved O2 concentrations in the nanomolar range, enabling it to be widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O2.
Abstract: The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth’s evolution. Among the various geochemical proxies for the presence of O2 in the environment, molecular fossils offer a unique record of O2 where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires molecular oxygen, fossil steranes have been used to draw inferences about aerobiosis in the early Precambrian. However, better quantitative constraints on the O2 requirement of this biochemistry would clarify the implications of these molecular fossils for environmental conditions at the time of their production. Here we demonstrate that steroid biosynthesis is a microaerobic process, enabled by dissolved O2 concentrations in the nanomolar range. We present evidence that microaerobic marine environments (where steroid biosynthesis was possible) could have been widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O2. In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today.
92 citations
TL;DR: The experimental methods developed for physico-chemical and functional studies of membrane cytochromes P450 incorporated in Nanodiscs allow for more detailed understanding of the scientific questions along the lines pioneered by Professor Klaus Ruckpaul and his array of colleagues and collaborators.
92 citations
TL;DR: The protease-resistant domain of N-218 MLN64, and by inference the corresponding domain of StAR, may have direct roles in their action to foster the flux of cholesterol from the outer to inner mitochondrial membrane.
Abstract: The steroidogenic acute regulatory protein (StAR) facilitates the movement of cholesterol from the outer to inner mitochondrial membrane in adrenal and gonadal cells, fostering steroid biosynthesis...
92 citations