Journal articles: 'Stenol'

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Zhou, Wenxu, Paxtyn M. Fisher, Boden H. Vanderloop та ін. "A nematode sterol C4α-methyltransferase catalyzes a new methylation reaction responsible for sterol diversity". Journal of Lipid Research 61, № 2 (2019): 192–204. http://dx.doi.org/10.1194/jlr.ra119000317.

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Primitive sterol evolution plays an important role in fossil record interpretation and offers potential therapeutic avenues for human disease resulting from nematode infections. Recognizing that C4-methyl stenol products [8(14)-lophenol] can be synthesized in bacteria while C4-methyl stanol products (dinosterol) can be synthesized in dinoflagellates and preserved as sterane biomarkers in ancient sedimentary rock is key to eukaryotic sterol evolution. In this regard, nematodes have been proposed to convert dietary cholesterol to 8(14)-lophenol by a secondary metabolism pathway that could involve sterol C4 methylation analogous to the C2 methylation of hopanoids (radicle-type mechanism) or C24 methylation of sterols (carbocation-type mechanism). Here, we characterized dichotomous cholesterol metabolic pathways in Caenorhabditis elegans that generate 3-oxo sterol intermediates in separate paths to lophanol (4-methyl stanol) and 8(14)-lophenol (4-methyl stenol). We uncovered alternate C3-sterol oxidation and Δ7 desaturation steps that regulate sterol flux from which branching metabolite networks arise, while lophanol/8(14)-lophenol formation is shown to be dependent on a sterol C4α-methyltransferse (4-SMT) that requires 3-oxo sterol substrates and catalyzes a newly discovered 3-keto-enol tautomerism mechanism linked to S-adenosyl-l-methionine-dependent methylation. Alignment-specific substrate-binding domains similarly conserved in 4-SMT and 24-SMT enzymes, despite minimal amino acid sequence identity, suggests divergence from a common, primordial ancestor in the evolution of methyl sterols. The combination of these results provides evolutionary leads to sterol diversity and points to cryptic C4-methyl steroidogenic pathways of targeted convergence that mediate lineage-specific adaptations.

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Alfken, Susanne, Lars Wörmer, Julius S. Lipp, et al. "Disrupted coherence between upwelling strength and redox conditions reflects source water change in Santa Barbara Basin during the 20th century." Paleoceanography and Paleoclimatology 36, no. 12 (2021): e2021PA004354. https://doi.org/10.1029/2021PA004354.

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Abstract Varved sediments from the center of the Santa Barbara Basin (SBB) off southern California are a valuable archive for high-resolution climate reconstruction. Using mass spectrometry imaging of lipid biomarkers, this study examines interactions of perennial upwelling strength and oxygen-driven redox conditions at the sediment-water interface from 1900 CE to 2009. In the SBB, variations in upwelling are recorded by isoprenoidal tetraethers from planktonic archaea, while the redox-sensitive C<sub>29</sub> stanol/stenol ratio reflects oxygen content in the bottom water and surficial sediment. The changing coherence of these two proxies allows investigation of the interplay between upwelling, bioproductivity and redox conditions, and their dependence on SBB source water composition during the 20th century. Prior to a large-scale oceanographic regime shift observed in the North Pacific in the 1970s, both proxies are positively correlated: periods of enhanced upwelling promoted mixing, resulting in increased oxygen availability at the sediment-water interface; conversely periods of reduced upwelling favored development of oxygen-depleted water at depth. In the wake of the basin-wide regime shift, changing oceanographic conditions led to a reduction in the southward flowing California Current and a stronger influence of the poleward California Undercurrent, which increased stratification and the supply of warm, oxygen-poor tropical water in the subsurface. As a result, oxygen availability in SBB bottom waters was predominantly regulated by upwelling-induced productivity and subsequent oxygen-consuming remineralization of organic matter.

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Bogus, K. A., K. A. F. Zonneveld, D. Fischer, S. Kasten, G. Bohrmann, and G. J. M. Versteegh. "The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies." Biogeosciences 9, no. 4 (2012): 1553–70. http://dx.doi.org/10.5194/bg-9-1553-2012.

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Abstract. A valid assessment of selective aerobic degradation on organic matter (OM) and its impact on OM-based proxies is vital to produce accurate environmental reconstructions. However, most studies investigating these effects suffer from inherent environmental heterogeneities. In this study, we used surface samples collected along two meter-scale transects and one longer transect in the northeastern Arabian Sea to constrain initial OM heterogeneity, in order to evaluate selective aerobic degradation on temperature, productivity and alteration indices at the sediment-water interface. All of the studied alteration indices, the higher plant alkane index, alcohol preservation index, and diol oxidation index, demonstrated that they are sensitive indicators for changes in the oxygen regime. Several export production indices, a cholesterol-based stanol/stenol index and dinoflagellate lipid- and cyst-based ratios, showed significant (more than 20%) change only over the lateral oxygen gradients. Therefore, these compounds do not exclusively reflect surface water productivity, but are significantly altered after deposition. Two of the proxies, glycerol dibiphytanyl glycerol tetraether-based TEX86 sea surface temperature indices and indices based on phytol, phytane and pristane, did not show any trends related to oxygen. Nevertheless, unrealistic sea surface temperatures were obtained after application of the TEX86, TEX86L, and TEX86H proxies. The phytol-based ratios were likely affected by the sedimentary production of pristane. Our results demonstrate the selective impact of aerobic organic matter degradation on the lipid and palynomorph composition of surface sediments along a short lateral oxygen gradient and suggest that some of the investigated proxies may be useful tracers of changing redox conditions at the sediment-water interface.

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Bogus, K. A., K. A. F. Zonneveld, D. Fischer, S. Kasten, G. Bohrmann, and G. J. M. Versteegh. "The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies." Biogeosciences Discussions 8, no. 6 (2011): 11359–403. http://dx.doi.org/10.5194/bgd-8-11359-2011.

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Abstract. A valid assessment of selective aerobic degradation on organic matter (OM) and its impact on OM-based proxies is vital to produce accurate environmental reconstructions. However, most studies investigating these effects suffer from inherent environmental heterogeneities. This includes differences in the initial OM composition, as a result of variable upper water column conditions, or from those induced by selective aerobic degradation. In this study, we used surface samples collected along two meter-scale transects and one longer transect in the northeastern Arabian Sea to constrain initial OM heterogeneity, in order to evaluate selective aerobic degradation on temperature, productivity and alteration indices at the sediment-water interface. All of the alteration indices, the higher plant alkane index, alcohol preservation index, and diol oxidation index, demonstrated that they are sensitive indicators for changes in oxygen content at the sediment-water interface. The export production indices, a cholesterol-based stanol/stenol and dinoflagellate lipid- and cyst-based ratios, showed significant (more than 20%) change over the lateral oxygen gradients. Therefore, they do not exclusively reflect surface water productivity, but can be altered after deposition with varying oxygen content at the sediment-water interface. Two of the investigated proxies, the glycerol dibiphytanyl glycerol tetraethers (GDGT) based TEX86 sea surface temperature indices and a productivity index based on phytol, phytane and pristane, did not show any trends related to oxygen concentration at the sediment-water interface. Nevertheless, unrealistic sea surface temperatures were obtained after application of the TEX86, TEX86L, and TEX86H proxies. The phytol-based ratios were likely modified by the sedimentary production of pristane. Our results demonstrate the rapid and selective impact of aerobic organic matter degradation on the lipid and palynomorph composition of surface sediments on a small spatial scale and suggests useful tracers of changing redox conditions along the sediment-water interface.

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Annaratone, C., A. Caligiani, M. Cirlini, L. Toffanin, and G. Palla. "Sterols, Sterol Oxides and CLA in Typical Meat Products from Pigs Fed with Different Diets." Czech Journal of Food Sciences 27, Special Issue 1 (2009): S220—S223. http://dx.doi.org/10.17221/611-cjfs.

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The effect on sterol stability and CLA content in meats from pigs fed with diets having different contents of oleic and linoleic acid was studied, considering typical Italian products seasoned with or without nitrates and ascorbates. Results showed that the increase of oleic acid in the diet leads to seasoned products with higher contents of oleic acid and lower content of linoleic acid and CLA. A different partition of sterols and sterol oxides was observed in the fat and in the muscle of all the products, with slightly higher amounts of cholesterol and sterol oxides in the muscle. Meat products seasoned in presence of ascorbates showed slightly lower amounts of sterol oxides in respect to those added with nitrates. The statistical treatment of the data showed that fatty acids distribution allow to discriminate between meats from different diets.

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Hujová, Alžběta, Jana Jarošová, Peter Mačinga, et al. "Biodegradable stents in the treatment of biliary strictures after liver transplantation – first experience." Gastroenterologie a hepatologie 78, no. 4 (2024): 286–90. http://dx.doi.org/10.48095/ccgh2024286.

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Summary: Biliary anastomotic strictures are one of the most common biliary complications in patients after liver transplantation. Biliary complications are associated with higher mortality, morbidity, risk of graft failure and usually require repeated endoscopic interventions with regular stent replacement for treatment. Biodegradable stents are new types of stents made of bio degradable polymers, which may have the main advantage of reducing the number of endoscopic interventions and associated complications. The aim of our article was to describe the cases of two patients after liver transplantation with early biliary anastomotic strictures, which were resolved by endoscopic placement of bio degradable stents. In both cases, endoscopic stent placement was technically feasible and there were no periprocedural or postprocedural complications. The clinical course and fol low-up imaging at 8 months showed regression of the strictures in both patients. Key words: liver transplantation – benign biliary stenoses – bio degradable stent

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7

Ceschim, Liziane M. M., Ana L. L. Dauner, Rosalinda C. Montone, Rubens C. L. Figueira, and César C. Martins. "Depositional history of sedimentary sterols around Penguin Island, Antarctica." Antarctic Science 28, no. 6 (2016): 443–54. http://dx.doi.org/10.1017/s0954102016000274.

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AbstractLipid biomarkers are potential tools for identifying the sources, diagenesis and reactivity of organic matter (OM) in marine systems, including in Antarctica where the particular environmental characteristics have motivated several studies of organic markers. Sedimentary sterol distributions were determined in two sediment cores (PGI-1 and PGI-2) collected from the marine environment around Penguin Island, Antarctica, during the 2007–08 summer. The cores were sectioned at 1 cm intervals and the sterols were analysed using gas chromatography with flame ionization detection. The results indicate that the sterols were subjected to decades of degradation and transformation with depth in both cores. However, an expected progressive conversion of stenols to stanols (evaluated by 5α-stanols/Δ5-stenols ratio) within the deepest sediment layers was not clear, suggesting low degradation rates. In PGI-1, the deposition of large quantities of penguin guano affected the distribution of sterols and, consequently, primary production was favoured by the ornithogenic soil input. The results contribute to the understanding of the current processes associated with primary sources and transformation of OM in this important region of the Antarctic environment.

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8

Veselka, Josef, Petra Zimolová, Pavel Stanka, et al. "Implantation of stents into significant carotid artery stenoses using the FilterWire EZ^TM system." Cor et Vasa 51, no. 4 (2009): 255–59. http://dx.doi.org/10.33678/cor.2009.064.

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9

Matkulčík, Peter, Tomáš Rohan, Michal Uher, Jakub Hustý, Milan Dastych, and Tomáš Andrašina. "Retrospective analysis of complications associated with metallic esophageal stents implanted under fluoroscopy inside malignant stenoses." Česká radiologie 75, no. 2 (2021): 164–71. https://doi.org/10.55095/cesradiol2021/020.

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10

Klinger, M. I. "Low-temperature properties of nonmetallic glasses." Uspekhi Fizicheskih Nauk 160, no. 1 (1990): 159. http://dx.doi.org/10.3367/ufnr.0160.199001g.0159.

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11

KILINÇ, Adnan, Nesrin SARUHAN, Mehmet Zahit BAŞ, and Ümit ERTAŞ. "A Major Salivary Gland Calculi in Stenon Duct: Case Report." Turkiye Klinikleri Journal of Dental Sciences Cases 1, no. 4 (2015): 272–75. http://dx.doi.org/10.5336/dentalcase.2015-47835.

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12

Takeshima, Mika, Mari H. Ogihara, and Hiroshi Kataoka. "Sterol Characteristics in Silkworm Brain and Various Tissues Characterized by Precise Sterol Profiling Using LC-MS/MS." International Journal of Molecular Sciences 20, no. 19 (2019): 4840. http://dx.doi.org/10.3390/ijms20194840.

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Sterols, especially cholesterol (Chl), are fundamental for animal survival. Insects lacking the ability to synthesize Chl are sterol auxotrophic animals and utilize dietary Chl and phytosterols to survive. The sterols obtained from a diet are distributed to the tissues; however, sterol homeostasis in insect tissues remains to be elucidated. This study sought to understand the sterol characteristics of insect tissues through detailed sterol quantification and statistics. The combination of sterol quantification using liquid chromatography tandem mass spectrometry (LC-MS/MS) and principal component analysis (PCA) revealed tissue-specific sterol characteristics in the silkworm, Bombyx mori, a phytophagous insect. We found that insect tissues have tissue-intrinsic sterol profiles. The brain has a unique sterol composition as compared to other tissues—high concentration of Chl and less accumulation of phytosterols. Other tissues also have intrinsic sterol characteristics, which when defined by dietary sterols or Chl metabolites, indicate preference for a sterol and consistently manage their own sterol homeostasis. Though most tissues never change sterol profiles during development, the brain drastically changes its sterol profile at the wandering stage, indicating that it could alter sterol composition in preparation for metamorphosis. These results suggest the existence of tissue- and sterol-specific systems for sterol homeostasis in insects.

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13

Dahlin, Paul, and Andrea Caroline Ruthes. "Loss of Sterol Biosynthesis in Economically Important Plant Pests and Pathogens: A Review of a Potential Target for Pest Control." Biomolecules 14, no. 11 (2024): 1435. http://dx.doi.org/10.3390/biom14111435.

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Sterol biosynthesis is a crucial metabolic pathway in plants and various plant pathogens. Their vital physiological role in multicellular organisms and their effects on growth and reproduction underline their importance as membrane compounds, hormone precursors, and signaling molecules. Insects, nematodes, and oomycetes of the Peronosporales group, which harbor important agricultural pests and pathogens, have lost the ability to synthesize their own sterols. These organisms rely on the acquisition of sterols from their host and are dependent on the sterol composition of the host. It is thought that sterol-synthesizing enzymes were lost during co-evolution with the hosts, which provided the organisms with sufficient amounts of the required sterols. To meet the essential requirements of these organisms, some sterol auxotrophs retained a few remaining sterol-modifying enzymes. Several molecular and biochemical investigations have suggested promising avenues for pest and pathogen control by targeting host sterol composition, sterol uptake, or sterol modification in organisms that have lost the ability to biosynthesize sterol de novo. This review examines the loss of sterol biosynthesis de novo in insects, nematodes, and oomycetes with the aim of investigating the sterol metabolic constraints and sterol acquisition of these organisms. This will shed light on its potential as a control target for the management of sterol-dependent organisms in a comprehensive agronomic approach.

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Jing, Xiangfeng, and Spencer T. Behmer. "Insect Sterol Nutrition: Physiological Mechanisms, Ecology, and Applications." Annual Review of Entomology 65, no. 1 (2020): 251–71. http://dx.doi.org/10.1146/annurev-ento-011019-025017.

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Insects, like all eukaryotes, require sterols for structural and metabolic purposes. However, insects, like all arthropods, cannot make sterols. Cholesterol is the dominant tissue sterol for most insects; insect herbivores produce cholesterol by metabolizing phytosterols, but not always with high efficiency. Many insects grow on a mixed-sterol diet, but this ability varies depending on the types and ratio of dietary sterols. Dietary sterol uptake, transport, and metabolism are regulated by several proteins and processes that are relatively conserved across eukaryotes. Sterol requirements also impact insect ecology and behavior. There is potential to exploit insect sterol requirements to ( a) control insect pests in agricultural systems and ( b) better understand sterol biology, including in humans. We suggest that future studies focus on the genetic mechanism of sterol metabolism and reverse transportation, characterizing sterol distribution and function at the cellular level, the role of bacterial symbionts in sterol metabolism, and interrupting sterol trafficking for pest control.

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Iaea, David B., Shu Mao, Frederik W. Lund, and Frederick R. Maxfield. "Role of STARD4 in sterol transport between the endocytic recycling compartment and the plasma membrane." Molecular Biology of the Cell 28, no. 8 (2017): 1111–22. http://dx.doi.org/10.1091/mbc.e16-07-0499.

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Cholesterol is an essential constituent of membranes in mammalian cells. The plasma membrane and the endocytic recycling compartment (ERC) are both highly enriched in cholesterol. The abundance and distribution of cholesterol among organelles are tightly controlled by a combination of mechanisms involving vesicular and nonvesicular sterol transport processes. Using the fluorescent cholesterol analogue dehydroergosterol, we examined sterol transport between the plasma membrane and the ERC using fluorescence recovery after photobleaching and a novel sterol efflux assay. We found that sterol transport between these organelles in a U2OS cell line has a t1/2 =12–15 min. Approximately 70% of sterol transport is ATP independent and therefore is nonvesicular. Increasing cellular cholesterol levels dramatically increases bidirectional transport rate constants, but decreases in cholesterol levels have only a modest effect. A soluble sterol transport protein, STARD4, accounts for ∼25% of total sterol transport and ∼33% of nonvesicular sterol transport between the plasma membrane and ERC. This study shows that nonvesicular sterol transport mechanisms and STARD4 in particular account for a large fraction of sterol transport between the plasma membrane and the ERC.

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Klinger, M. I. "Low-temperature properties and localized electronic states of glasses." Uspekhi Fizicheskih Nauk 152, no. 8 (1987): 623. http://dx.doi.org/10.3367/ufnr.0152.198708d.0623.

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SALMAN, Hakan, Yeliz KART, Çiğdem KAPLAN, and Mustafa AKÇAM. "Delayed Diagnosis of Diaphragmatic Rectal Stenosis." Turkiye Klinikleri Journal of Pediatrics 30, no. 3 (2021): 235–38. http://dx.doi.org/10.5336/pediatr.2021-83065.

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Ramachandra Rao, Sriganesh, and Steven J. Fliesler. "Bottlenecks in the Investigation of Retinal Sterol Homeostasis." Biomolecules 14, no. 3 (2024): 341. http://dx.doi.org/10.3390/biom14030341.

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Sterol homeostasis in mammalian cells and tissues involves balancing three fundamental processes: de novo sterol biosynthesis; sterol import (e.g., from blood-borne lipoproteins); and sterol export. In complex tissues, composed of multiple different cell types (such as the retina), import and export also may involve intratissue, intercellular sterol exchange. Disruption of any of these processes can result in pathologies that impact the normal structure and function of the retina. Here, we provide a brief overview of what is known currently about sterol homeostasis in the vertebrate retina and offer a proposed path for future experimental work to further our understanding of these processes, with relevance to the development of novel therapeutic interventions for human diseases involving defective sterol homeostasis.

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Murray, Derek Gordon, Michael Isard, and Yuan Yu. "Steno." ACM SIGPLAN Notices 47, no. 6 (2012): 121. http://dx.doi.org/10.1145/2345156.1993513.

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Murray, Derek Gordon, Michael Isard, and Yuan Yu. "Steno." ACM SIGPLAN Notices 46, no. 6 (2011): 121–31. http://dx.doi.org/10.1145/1993316.1993513.

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21

Benveniste, Pierre. "Sterol Metabolism." Arabidopsis Book 1 (January 2002): e0004. http://dx.doi.org/10.1199/tab.0004.

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Benveniste, P. "Sterol Biosynthesis." Annual Review of Plant Physiology 37, no. 1 (1986): 275–308. http://dx.doi.org/10.1146/annurev.pp.37.060186.001423.

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Lv, Qun, Jianjun Wang та Zhaoyang Ruan. "Mechanism of Dandelion Sterol in Treating Pulmonary Fibrosis Through Transforming Growth Factor-β Signaling Pathway". Journal of Biomaterials and Tissue Engineering 11, № 4 (2021): 612–18. http://dx.doi.org/10.1166/jbt.2021.2568.

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Background: The paper aimed to elucidate the molecular mechanism of Dandelion sterol in the treatment of pulmonary fibrosis, to study its effect on EMT of lung epithelial cells, and to find its target and downstream signaling pathways. Material and methods: The effects of Dandelion sterol on parathyroid (PQ)-induced EMT in lung epithelial cells were studied by immunofluorescence method. Immunohistochemistry and western-blot methods were used to verify that Dandelion sterol inhibited TGF-β1-induced EMT at the cellular level in animals, demonstrating that Dandelion sterol targets TGF-β1 to exert an anti-pulmonary fibrosis effect. Results: Dandelion sterol significantly inhibited PQ-induced migration and invasion of lung epithelial cells, and also inhibited the induced EMT. Dandelion sterol had a proper binding activity with the lung fibrosis-inducing factor TGF-β1. Dandelion sterol inhibited the TGF-β1-induced EMT process, and acted to treat pulmonary fibrosis by inhibiting the TGF-β1/Smad3 signaling pathway. Conclusion: Dandelion sterol can inhibit the pulmonary fibrosis by inhibiting the EMT process of lung epithelial cells through targeting the TGF- β1/Smad signaling pathway.

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Iyengar, S. Raghava, J. Shashidhara Prasad, and Shanta Venkataraman. "Vibrational Spectra of Sterol and Non-sterol Cholesterogens." Molecular Crystals and Liquid Crystals 146, no. 1 (1987): 265–85. http://dx.doi.org/10.1080/00268948708071818.

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Lin, Don S., Robert D. Steiner, Louise S. Merkens, Anuradha S. Pappu, and William E. Connor. "The effects of sterol structure upon sterol esterification." Atherosclerosis 208, no. 1 (2010): 155–60. http://dx.doi.org/10.1016/j.atherosclerosis.2009.07.031.

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Junker, Julia, Isabelle Chong, Frits Kamp, et al. "Comparison of Strategies for the Determination of Sterol Sulfates via GC-MS Leading to a Novel Deconjugation-Derivatization Protocol." Molecules 24, no. 13 (2019): 2353. http://dx.doi.org/10.3390/molecules24132353.

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Sulfoconjugates of sterols play important roles as neurosteroids, neurotransmitters, and ion channel ligands in health and disease. In most cases, sterol conjugate analysis is performed with liquid chromatography-mass spectrometry. This is a valuable tool for routine analytics with the advantage of direct sterol sulfates analysis without previous cleavage and/or derivatization. The complementary technique gas chromatography-mass spectrometry (GC-MS) is a preeminent discovery tool in the field of sterolomics, but the analysis of sterol sulfates is hampered by mandatory deconjugation and derivatization. Despite the difficulties in sample workup, GC-MS is an indispensable tool for untargeted analysis and steroid profiling. There are no general sample preparation protocols for sterol sulfate analysis using GC-MS. In this study we present a reinvestigation and evaluation of different deconjugation and derivatization procedures with a set of representative sterol sulfates. The advantages and disadvantages of trimethylsilyl (TMS), methyloxime-trimethylsilyl (MO-TMS), and trifluoroacetyl (TFA) derivatives were examined. Different published procedures of sterol sulfate deconjugation, including enzymatic and chemical cleavage, were reinvestigated and examined for diverse sterol sulfates. Finally, we present a new protocol for the chemical cleavage of sterol sulfates, allowing for simultaneous deconjugation and derivatization, simplifying GC-MS based sterol sulfate analysis.

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York, Autumn, Joseph Argus, Anjie Zhen, et al. "Reprogramming lipid metabolism primes host antiviral immunity (INM7P.431)." Journal of Immunology 192, no. 1_Supplement (2014): 123.9. http://dx.doi.org/10.4049/jimmunol.192.supp.123.9.

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Abstract Oxysterols, or oxidized derivatives of cholesterol, have emerged as important regulators of adaptive and innate immunity. However, the molecular mechanisms by which these lipids facilitate host defense remain indeterminate. To better understand how cellular sterol metabolism influences innate immunity, we have generated gain- and loss-of-function macrophages that have key components of sterol homeostasis perturbed. Remarkably, we find that genetic manipulation of sterol biosynthetic capacity, and cellular sterol homeostasis, intrinsically alters its innate immune program. Genetic inhibition of the sterol biosynthetic pathway renders cells intrinsically resistant to pathogen challenge. Conversely, ectopically enforcing a sterol synthetic program renders cells more susceptible to viral infections. Mechanistic studies indicate that disruption of sterol synthesis in macrophages activates an array of host defense pathways, most notably a robust type 1 IFN response and upregulation of the anti-viral proteins MX-1 and MX-2. Current studies are focused on defining how inhibition of the sterol biosynthetic pathway engages anti-viral immunity and determining if this response is broadly applicable to other cell types. These studies provide proof -of-principle evidence that direct manipulation of sterol homeostatic state of a cell is intimately associated with host defense and suggests that metabolic manipulation converts a cell from a permissive to resistant viral immune state.

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Yao, Jiang Ning, Nan Qing Liao, and Hao Ming Li. "Characterization and Bioinformatics Analysis of C-4 Sterol Methyl Oxidase from Monascus purpureus." Applied Mechanics and Materials 522-524 (February 2014): 247–50. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.247.

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A gene encoding a putative C-4 sterol methyl oxidase was obtained by screening Monascus purpureus cDNA library. Bioinformatics analysis showed that this protein has a primary structure, a hydrophobicity profile and a pattern of histidine-rich motifs which are typical of C-4 methyl sterol oxidases. The deduced C-4 sterol methyl oxidase protein of M. purpureus contained 259 amino acid, with molecular mass of 30,299Da. Sequence alignment analysis revealed that M. purpureus deduced C-4 sterol methyl oxidase was closely related to C-4 sterol methyl oxidase from Aspergillus, Penicillium and Byssochlamys, and highly homologous to aforementioned and other known C-4 sterol methyl oxidase. The deduced protein is of a membrane protein with two transmembrane helices, which belongs to the fatty acid hydroxylase superfamily. The consistency of the comparison results of the primary structure, secondary structure and physicochemical properties suggests that the dedued protein may well be C-4 sterol methyl oxidase.

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Zheng Koh, Dylan Hong, and Yasunori Saheki. "Regulation of Plasma Membrane Sterol Homeostasis by Nonvesicular Lipid Transport." Contact 4 (January 2021): 251525642110424. http://dx.doi.org/10.1177/25152564211042451.

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Sterol contributes to the structural integrity of cellular membranes and plays an important role in the regulation of cell signaling in eukaryotes. It is either produced in the endoplasmic reticulum or taken up from the extracellular environment. In most eukaryotic cells, however, the majority of sterol is enriched in the plasma membrane. Thus, the transport of sterol between the plasma membrane and other organelles, including the endoplasmic reticulum, is crucial for maintaining sterol homeostasis. While vesicular transport that relies on membrane budding and fusion reactions plays an important role in bulk sterol transport, this mode of transport is slow and non-selective. Growing evidence suggests a critical role of nonvesicular transport mediated by evolutionarily conserved families of lipid transfer proteins in more rapid and selective delivery of sterol. Some lipid transfer proteins act primarily at the sites of contacts formed between the endoplasmic reticulum and other organelles or the plasma membrane without membrane fusion. In this review, we describe the similarities and differences of sterol biosynthesis and uptake in mammals and yeast and discuss the role of their lipid transfer proteins in maintaining plasma membrane sterol homeostasis.

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Lin, Meng, Heike Unden, Nicolas Jacquier, Roger Schneiter, Ursula Just, and Thomas Höfken. "The Cdc42 Effectors Ste20, Cla4, and Skm1 Down-Regulate the Expression of Genes Involved in Sterol Uptake by a Mitogen-activated Protein Kinase-independent Pathway." Molecular Biology of the Cell 20, no. 22 (2009): 4826–37. http://dx.doi.org/10.1091/mbc.e09-01-0034.

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In Saccharomyces cerevisiae, the Rho-type GTPase Cdc42 regulates polarized growth through its effectors, including the p21-activated kinases (PAKs) Ste20, Cla4, and Skm1. Previously, we demonstrated that Ste20 interacts with several proteins involved in sterol synthesis that are crucial for cell polarization. Under anaerobic conditions, sterols cannot be synthesized and need to be imported into cells. Here, we show that Ste20, Cla4, and Skm1 form a complex with Sut1, a transcriptional regulator that promotes sterol uptake. All three PAKs can translocate into the nucleus and down-regulate the expression of genes involved in sterol uptake, including the Sut1 targets AUS1 and DAN1 by a novel mechanism. Consistently, deletion of either STE20, CLA4, or SKM1 results in an increased sterol influx and PAK overexpression inhibits sterol uptake. For Ste20, we demonstrate that the down-regulation of gene expression requires nuclear localization and kinase activity of Ste20. Furthermore, the Ste20-mediated control of expression of sterol uptake genes depends on SUT1 but is independent of a mitogen-activated protein kinase signaling cascade. Together, these observations suggest that PAKs translocate into the nucleus, where they modulate expression of sterol uptake genes via Sut1, thereby controlling sterol homeostasis.

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Fujii, Thais Tenorio Soares, Pollyanna Stephanie Gomes, Rubens Lima do Monte-Neto, et al. "Simvastatin Resistance of Leishmania amazonensis Induces Sterol Remodeling and Cross-Resistance to Sterol Pathway and Serine Protease Inhibitors." Microorganisms 10, no. 2 (2022): 398. http://dx.doi.org/10.3390/microorganisms10020398.

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The sterol biosynthesis pathway of Leishmania spp. is used as a pharmacological target; however, available information about the mechanisms of the regulation and remodeling of sterol-related genes is scarce. The present study investigated compensatory mechanisms of the sterol biosynthesis pathway using an inhibitor of HMG-CoA reductase (simvastatin) and by developing drug-resistant parasites to evaluate the impact on sterol remodeling, cross-resistance, and gene expression. Simvastatin-resistant L. amazonensis parasites (LaSimR) underwent reprogramming of sterol metabolism manifested as an increase in cholestane- and stigmastane-based sterols and a decrease in ergostane-based sterols. The levels of the transcripts of sterol 24-C-methyltransferase (SMT), sterol C14-α-demethylase (C14DM), and protease subtilisin (SUB) were increased in LaSimR. LaSimR was cross-resistance to ketoconazole (a C14DM inhibitor) and remained sensitive to terbinafine (an inhibitor of squalene monooxygenase). Sensitivity of the LaSimR mutant to other antileishmanial drugs unrelated to the sterol biosynthesis pathway, such as trivalent antimony and pentamidine, was similar to that of the wild-type strain; however, LaSimR was cross-resistant to miltefosine, general serine protease inhibitor N-p-tosyl-l-phenylalanine chloromethyl ketone (TPCK), subtilisin-specific inhibitor 4-[(diethylamino)methyl]-N-[2-(2-methoxyphenyl)ethyl]-N-(3R)-3-pyrrolidinyl-benzamide dihydrochloride (PF-429242), and tunicamycin. The findings on the regulation of the sterol pathway can support the development of drugs and protease inhibitors targeting this route in parasites.

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Ness, Frédérique, Tilman Achstetter, Catherine Duport, Francis Karst, Roberto Spagnoli, and Eric Degryse. "Sterol Uptake in Saccharomyces cerevisiae Heme Auxotrophic Mutants Is Affected by Ergosterol and Oleate but Not by Palmitoleate or by Sterol Esterification." Journal of Bacteriology 180, no. 7 (1998): 1913–19. http://dx.doi.org/10.1128/jb.180.7.1913-1919.1998.

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ABSTRACT The relationship between sterol uptake and heme competence in two yeast strains impaired in heme synthesis, namely, G204 and H12-6A, was analyzed. To evaluate heme availability, a heterologous 17α-hydroxylase cytochrome P-450 cDNA (P-450c17) was expressed in these strains, and its activity was measured in vivo. Heme deficiency in G204 led to accumulation of squalene and lethality. The heterologous cytochrome P-450 was inactive in this strain. The leaky H12-6A strain presented a slightly modified sterol content compared to that for the wild type, and the P-450c17 recovered partial activity. By analyzing sterol transfer on nongrowing cells, it was shown that the cells were permeable toward exogenous cholesterol when they were depleted of endogenous sterols, which was the case for G204 but not for H12-6A. It was concluded that the fully blocked heme mutant (G204) replenishes its diminishing endogenous sterol levels during growth by replacement with sterol from the outside medium. Endogenous sterol biosynthesis appears to be the primary factor capable of excluding exogenous sterol. Oleate but not palmitoleate was identified as a component that reduced but did not prevent sterol transfer. Sterol transfer was only slightly affected by a lack of esterification. It is described herein how avoidance of the potential cytotoxicity of the early intermediates of the mevalonate pathway could be achieved by a secondary heme mutation inerg auxotrophs.

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Lee, Alysha K., Amy B. Banta, Jeremy H. Wei, et al. "C-4 sterol demethylation enzymes distinguish bacterial and eukaryotic sterol synthesis." Proceedings of the National Academy of Sciences 115, no. 23 (2018): 5884–89. http://dx.doi.org/10.1073/pnas.1802930115.

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Sterols are essential eukaryotic lipids that are required for a variety of physiological roles. The diagenetic products of sterol lipids, sterane hydrocarbons, are preserved in ancient sedimentary rocks and are utilized as geological biomarkers, indicating the presence of both eukaryotes and oxic environments throughout Earth’s history. However, a few bacterial species are also known to produce sterols, bringing into question the significance of bacterial sterol synthesis for our interpretation of sterane biomarkers. Recent studies suggest that bacterial sterol synthesis may be distinct from what is observed in eukaryotes. In particular, phylogenomic analyses of sterol-producing bacteria have failed to identify homologs of several key eukaryotic sterol synthesis enzymes, most notably those required for demethylation at the C-4 position. In this study, we identified two genes of previously unknown function in the aerobic methanotrophic γ-ProteobacteriumMethylococcus capsulatusthat encode sterol demethylase proteins (Sdm). We show that a Rieske-type oxygenase (SdmA) and an NAD(P)-dependent reductase (SdmB) are responsible for converting 4,4-dimethylsterols to 4α-methylsterols. Identification of intermediate products synthesized during heterologous expression of SdmA-SdmB along with13C-labeling studies support a sterol C-4 demethylation mechanism distinct from that of eukaryotes. SdmA-SdmB homologs were identified in several other sterol-producing bacterial genomes but not in any eukaryotic genomes, indicating that these proteins are unrelated to the eukaryotic C-4 sterol demethylase enzymes. These findings reveal a separate pathway for sterol synthesis exclusive to bacteria and show that demethylation of sterols evolved at least twice—once in bacteria and once in eukaryotes.

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Sokolov, Svyatoslav S., Marina M. Popova, Peter Pohl, et al. "Structural Role of Plasma Membrane Sterols in Osmotic Stress Tolerance of Yeast Saccharomyces cerevisiae." Membranes 12, no. 12 (2022): 1278. http://dx.doi.org/10.3390/membranes12121278.

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Yeast S. cerevisiae has been shown to suppress a sterol biosynthesis as a response to hyperosmotic stress. In the case of sodium stress, the failure to suppress biosynthesis leads to an increase in cytosolic sodium. The major yeast sterol, ergosterol, is known to regulate functioning of plasma membrane proteins. Therefore, it has been suggested that the suppression of its biosynthesis is needed to adjust the activity of the plasma membrane sodium pumps and channels. However, as the sterol concentration is in the range of thirty to forty percent of total plasma membrane lipids, it is believed that its primary biological role is not regulatory but structural. Here we studied how lowering the sterol content affects the response of a lipid bilayer to an osmotic stress. In accordance with previous observations, we found that a decrease of the sterol fraction increases a water permeability of the liposomal membranes. Yet, we also found that sterol-free giant unilamellar vesicles reduced their volume during transient application of the hyperosmotic stress to a greater extent than the sterol-rich ones. Furthermore, our data suggest that lowering the sterol content in yeast cells allows the shrinkage to prevent the osmotic pressure-induced plasma membrane rupture. We also found that mutant yeast cells with the elevated level of sterol accumulated propidium iodide when exposed to mild hyperosmotic conditions followed by hypoosmotic stress. It is likely that the decrease in a plasma membrane sterol content stimulates a drop in cell volume under hyperosmotic stress, which is beneficial in the case of a subsequent hypo-osmotic one.

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Yao, Lihang, and Laura A. Woollett. "Adult sterol metabolism is not affected by a positive sterol balance in the neonatal Golden Syrian hamster." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, no. 3 (2005): R561—R566. http://dx.doi.org/10.1152/ajpregu.00353.2004.

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Dietary components impact metabolism early in life. Some of the diet-induced effects are long lasting and can lead to various adult-based diseases. In the current studies, we examined the short-term effects of dietary cholesterol on neonatal hepatic sterol metabolism and the long-term effects that those early-life diets had on sterol metabolism in adulthood. Neonatal hamsters began consuming solid food as a supplement to milk by 5 days of age; diets contained 0 or 2% added cholesterol (wt/wt). By 10 days of age, plasma and liver cholesterol concentrations were 3.2- and 2.5-fold greater, respectively, in the neonates fed cholesterol. Hepatic sterol synthesis rates were suppressed 65% in cholesterol-fed neonates compared with control neonates. By 20 days of age, plasma and liver cholesterol concentrations were still greater and sterol synthesis rates were now suppressed maximally in neonates fed cholesterol compared with control neonates. The expression level of an apolipoprotein B-containing lipoprotein receptor (low-density lipoprotein receptor-related protein) was greater and the mature form of the sterol regulatory element-binding protein-2 was similar in livers of 20-day-old control neonates compared with control neonates at 10 days of age. To test whether the change in sterol balance in the neonatal period had a lasting effect on hepatic sterol metabolism, all animals were weaned on a low-cholesterol diet. At 70 days of age, hepatic sterol synthesis rates, plasma lipoprotein and liver cholesterol concentrations, and bile acid pool sizes and compositions were measured. Sterol balance in the adults was similar between animals fed either diet early in life, as demonstrated by a lack of difference in any parameter measured. Thus, even though dietary cholesterol suppressed hepatic sterol synthesis rates dramatically in the neonatal hamster, the change has little impact on sterol balance later in life.

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Kalaiselvi, Dr B., Gogul S, and Mohammed Siddiq M. "Stegno-Hide." International Journal of Research Publication and Reviews 4, no. 11 (2023): 1935–38. http://dx.doi.org/10.55248/gengpi.4.1123.113115.

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Ergan, Begüm, Kutlay Aydın, Merve Demirci, Begüm Görgülü, Kemal Can Tertemiz, and Murat Emre Tokur. "A rare cause of noninvasive ventilation failure: tracheal stenosis." Tuberkuloz ve Toraks 65, no. 4 (2017): 333–36. http://dx.doi.org/10.5578/tt.53863.

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Pobell, F. "Acoustic properties of glasses and polycrystals at very low temperatures." Uspekhi Fizicheskih Nauk 164, no. 12 (1994): 1298. http://dx.doi.org/10.3367/ufnr.0164.199412m.1298.

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Da Silva, Tais Freitas, Sinda Beatriz Carvalhal Gomes, Frederico Sobrinho Da Silva, et al. "Lipid composition of the microbial mat from a hypersaline environment (Vermelha Lagoon, Rio de Janeiro, Brazil)." Journal of Sedimentary Research 91, no. 4 (2021): 349–61. http://dx.doi.org/10.2110/jsr.2021.01.

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ABSTRACT This study determines organic-matter (OM) composition in the different color layers of a stratified hypersaline microbial mat and verifies the hypothesis that each layer includes a distinct group of lipids. The relation of precursor lipids from the microbial mat to the hydrocarbon composition in fossil records was also evaluated. To that end, the composition was studied of glycolipids (GLs), phospholipids (PLs), and “neutral” lipids (NLs, including hydrocarbons, n-alkanols, sterols, hopanols, free fatty acids, and wax esters) in four different color layers (A–D; depth intervals: up to 0.5 cm, 0.5–1.0 cm, 1.5–3.0 cm, and 3.0–6.0 cm, respectively) of a stratified hypersaline mat from the Vermelha Lagoon, Rio de Janeiro, Brazil. Microscopic characterization revealed the presence of 16 cyanobacterial morphospecies, with predominance of Microcoleus chthonoplastes. The notable prevalence of saturated straight-chain fatty acids (FAs), n-16:0 and n-18:0 and their monounsaturated counterparts, n-16:1 and n-18:1 in all three lipid fractions (GLs, PLs, and NLs), associated with the domination of n-C17 alkane and n-C17:1 alkene among the hydrocarbons confirmed the main imprint of cyanobacteria. The composition of the studied lipid classes implies the contribution of sulfate-reducing bacteria such as Desulfomicrobium sp. strain, purple sulfur bacteria, as well as the possible input of Geobacter spp. and Desulfovibrio spp., particularly in the deeper layers. The notable decrease in total extractable lipids (TELs) yield from layers A to D indicates that lipid synthesis is far more intense by photosynthesizing cyanobacteria than by anaerobic microorganisms. The content of PLs was uniform and low (&lt; 5%) in all layers, implying their extremely quick degradation. GLs, followed by NLs, were the most abundant in all layers indicating the medium, which is characterized by carbon source excess and limited nitrogen source, which regulates microorganism growth. The upper layers, A (green) and B (reddish-brown) differ from those lower, C (dark brown greenish) and D (brown) according to the NLs/GLs ratio, which is higher in the former. The lipid compositions reveal distinctions between the individual layers in the microbial mat. The observed layers clearly differ according to the amount of high-molecular-weight (C22–C31) n-alkanes and long-chain (C21–C30) n-alkanols, the content of phytol, bishomohopanol, tetrahymanol, C27–C29 sterols, the stanol/stenol ratio in the neutral lipid fraction, as well as the content of branched (iso and anteiso) FAs and w9/w7 FA ratio in the GLs fraction. The mentioned parameters imply a greater contribution of sulfate-reducing and purple sulfur bacteria to layer B, higher impact of photosynthetic red algae in upper layers A and B, the elevated contribution of marine ciliate species, feeding on bacteria to layers B and C, as well as the increment of anoxygenic phototrophic and heterotrophic bacteria to layer D. The greatest capability for the synthesis of hydrocarbons is observed in layer B. The composition of lipid classes in the microbial mat showed a significant relationship with the most important biomarkers' fingerprints in the source rocks extracts and petroleum derived from the carbonate hypersaline environments, including the distribution of n-alkanes, a high abundance of phytane and gammacerane, as well as a distribution of C27–C29 regular steranes. Therefore, these results offer an insight into the transformation of microbial OM during the sedimentation processes in a hypersaline environment and its contribution to the fossil record.

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Jin, Kim Hyo, Jiwon Yang, Olupathage Indrachapa Udayanganie, et al. "Sterol isolated from Sargassum horneriattenuated particulate matter-exacerbated allergic asthma through the Th17 response." Journal of Immunology 210, no. 1_Supplement (2023): 67.05. http://dx.doi.org/10.4049/jimmunol.210.supp.67.05.

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Abstract Particulate matter (PM) has become a serious health issue causing pulmonary diseases such as asthma. Due to the side effects and non-specificity of conventional drugs, it is a need to develop alternative treatment using natural product. Sargassum horneri (S. horneri) is an edible species of large brown algae inhabiting the coasts of northeastern Asia extensively. S. horneri has sterols and has been used in oriental medicine to treat allergic condition. Therefore, we investigated if sterol isolated from S. horneri ethanol extract (SHE-sterol) could mitigate the PM-exacerbated allergic asthma. To establish a mouse model of asthma, BALB/c mice were sensitized with ovalbumin (OVA, 10 mg) and challenged with PM (5 mg/m 3) for 7 days consecutively. SHE-sterol (50, 200 mg/kg), Prednisone (5 mg/kg). In SHE-sterol, fucosterol was specially identified as 0.701 μg/mL. SHE-sterol attenuated the PM-aggravated granulocytes infiltration. Moreover, SHE-sterol further attenuated PM-exacerbated eosinophil infiltration in the lung, trachea, and BALF. In addition, SHE-sterol markedly mitigated the activation of mast cells and the IgE level in serum. Concomitantly, SHE-sterol further restrained the Th17 cell response in PM-exposed allergic mice through attenuating expression of relevant effector cytokine IL-17A. This resulted in mitigated neutrophil infiltration in the lung. Also, SHE-sterol significantly suppressed PM-exacerbated hypersecretion of mucus in asthmatic mice. Taken together, these results suggest that sterol isolated from SHE has therapeutic potential for treating PM-exacerbated allergic asthma. This research was funded by the Ministry of Education (2019R1A6A1A10072987 and 2022R1I1A1A01072505). This research was funded by the Ministry of Education (2019R1A6A1A10072987 and 2022R1I1A1A01072505).

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Schmid, Kara E., and Laura A. Woollett. "Differential effects of polyunsaturated fatty acids on sterol synthesis rates in adult and fetal tissues of the hamster: consequence of altered sterol balance." American Journal of Physiology-Gastrointestinal and Liver Physiology 285, no. 5 (2003): G796—G803. http://dx.doi.org/10.1152/ajpgi.00226.2003.

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Cholesterol is necessary for the proper growth and development of the fetus. Consequently, disruptions in cholesterol biosynthesis lead to abnormal fetal development. It has been shown that in cells exposed to polyunsaturated fatty acids (PUFA), the expressions of genes and activities of enzymes involved in cholesterol synthesis are reduced. Similarly, we found that adult male hamsters fed PUFA-enriched diets had an ≈60% reduction in in vivo hepatic sterol synthesis rates. If fetal tissues respond to PUFA in the same manner as do adult livers, then maternal dietary PUFA could lead to a reduction in fetal sterol synthesis rates and possibly abnormal development. To investigate the impact of maternal dietary fatty acids on fetal sterol synthesis rates, female hamsters were fed diets enriched in various fatty acids before and throughout gestation. In vivo sterol synthesis rates were measured in fetuses at mid- and late gestation. At both gestational stages, dietary PUFA had no effect on fetal sterol synthesis rates. This lack of effect was not a consequence of a lack of PUFA enrichment in fetal fatty acids or the lack of PUFA receptor expression in the fetus. We hypothesize that the fetus may experience a dysregulation of sterol synthesis as the result of the fetus being in a negative sterol balance; the PUFA-induced suppression of sterol synthesis in the adult male hamster liver was ablated by creating a net negative sterol balance across the adult hepatocyte.

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Jang, Jyan-Chyun, Shozo Fujioka, Masao Tasaka, et al. "A critical role of sterols in embryonic patterning and meristem programming revealed by the fackel mutants of Arabidopsis thaliana." Genes & Development 14, no. 12 (2000): 1485–97. http://dx.doi.org/10.1101/gad.14.12.1485.

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Here we report a novel Arabidopsis dwarf mutant,fackel-J79, whose adult morphology resembles that of brassinosteroid-deficient mutants but also displays distorted embryos, supernumerary cotyledons, multiple shoot meristems, and stunted roots. We cloned the FACKEL gene and found that it encodes a protein with sequence similarity to both the human sterol reductase family and yeast C-14 sterol reductase and is preferentially expressed in actively growing cells. Biochemical analysis indicates that the fk-J79mutation results in deficient C-14 sterol reductase activity, abnormal sterol composition, and reduction of brassinosteroids (BRs). Unlike other BR-deficient mutants, the defect of hypocotyl elongation infk-J79 cannot be corrected by exogenous BRs. The unique phenotypes and sterol composition in fk-J79 indicate crucial roles of sterol regulation and signaling in cell division and cell expansion in embryonic and post-embryonic development in plants.

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Ngo, Mike H., Terry R. Colbourne, and Neale D. Ridgway. "Functional implications of sterol transport by the oxysterol-binding protein gene family." Biochemical Journal 429, no. 1 (2010): 13–24. http://dx.doi.org/10.1042/bj20100263.

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Cholesterol and its numerous oxygenated derivatives (oxysterols) profoundly affect the biophysical properties of membranes, and positively and negatively regulate sterol homoeostasis through interaction with effector proteins. As the bulk of cellular sterols are segregated from the sensory machinery that controls homoeostatic responses, an important regulatory step involves sterol transport or signalling between membrane compartments. Evidence for rapid, energy-independent transport between organelles has implicated transport proteins, such as the eukaryotic family of OSBP (oxysterol-binding protein)/ORPs (OSBP-related proteins). Since the founding member of this family was identified more than 25 years ago, accumulated evidence has implicated OSBP/ORPs in sterol signalling and/or sterol transport functions. However, recent evidence of sterol transfer activity by OSBP/ORPs suggests that other seemingly disparate functions could be the result of alterations in membrane sterol distribution or ancillary to this primary activity.

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Dannaoui, Eric, Florence Persat, Elisabeth Borel, Marie-Antoinette Piens, and Stéphane Picot. "Sterol composition of itraconazole-resistant and itraconazole-susceptible isolates of Aspergillus fumigatus." Canadian Journal of Microbiology 47, no. 8 (2001): 706–10. http://dx.doi.org/10.1139/w01-066.

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Sterol composition of four clinical isolates of Aspergillus fumigatus resistant to itraconazole was determined by gas chromatography mass spectrometry and compared with that of four susceptible strains. For all strains, the major sterol was ergosterol. Sterol compositions were qualitatively and quantitatively similar for the resistant and susceptible strains. These results suggest that itraconazole resistance is not related, for the strains studied, to alterations in the ergosterol synthesis pathway.Key words: Aspergillus fumigatus, itraconazole resistance, sterol composition.

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Levine, Tim P. "Lipid traffic: Osh4p makes an unexpected exchange." Journal of Cell Biology 195, no. 6 (2011): 927–29. http://dx.doi.org/10.1083/jcb.201111074.

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A new study in this issue (De Saint-Jean et al. 2011. J. Cell Biol. http://dx.doi.org/jcb.201104062) reveals that the sterol transfer protein Osh4p can also transport the signaling phospholipid phosphatidylinositol 4-phosphate (PI(4)P), which binds to the same site in Osh4p as sterol. This finding helps explain some previously published studies and also indicates that lipid/sterol exchange could contribute to establishing a sterol gradient in cells.

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Kim, Myoung Sug, Hye Sung Choi, Hyun Ja Han, Doo Nam Kim, Du Hae An, and Sung Hee Jung. "Characteristics of Enterococcus faecium isolated from rough-toothed dolphin, Steno bredanensis." Journal of fish pathology 26, no. 3 (2013): 289–94. http://dx.doi.org/10.7847/jfp.2013.26.3.289.

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Vik, Åshild, and Jasper Rine. "Upc2p and Ecm22p, Dual Regulators of Sterol Biosynthesis in Saccharomyces cerevisiae." Molecular and Cellular Biology 21, no. 19 (2001): 6395–405. http://dx.doi.org/10.1128/mcb.21.19.6395-6405.2001.

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ABSTRACT Sterol levels affect the expression of many genes in yeast and humans. We found that the paralogous transcription factors Upc2p and Ecm22p of yeast were sterol regulatory element (SRE) binding proteins (SREBPs) responsible for regulating transcription of the sterol biosynthetic genes ERG2 and ERG3. We defined a 7-bp SRE common to these and other genes, including many genes involved in sterol biosynthesis. Upc2p and Ecm22p activatedERG2 expression by binding directly to this element in the ERG2 promoter. Upc2p and Ecm22p may thereby coordinately regulate genes involved in sterol homeostasis in yeast. Ecm22p and Upc2p are members of the fungus-specific Zn[2]-Cys[6] binuclear cluster family of transcription factors and share no homology to the analogous proteins, SREBPs, that are responsible for transcriptional regulation by sterols in humans. These results suggest that Saccharomyces cerevisiae and human cells regulate sterol synthesis by different mechanisms.

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Tansley, Gavin, Daniel T. Holmes, Dieter Lütjohann, Elizabeth Head, and Cheryl L. Wellington. "Sterol Lipid Metabolism in Down Syndrome Revisited: Down Syndrome Is Associated with a Selective Reduction in Serum Brassicasterol Levels." Current Gerontology and Geriatrics Research 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/179318.

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Over the past 15 years, insights into sterol metabolism have improved our understanding of the relationship between lipids and common conditions such as atherosclerosis and Alzheimer’s Disease (AD). A better understanding of sterol lipid metabolism in individuals with Down Syndrome (DS) may help elucidate how this population’s unique metabolic characteristics influence their risks for atherosclerosis and AD. To revisit the question of whether sterol lipid parameters may be altered in DS subjects, we performed a pilot study to assess traditional serum sterol lipids and lipoproteins, as well as markers of sterol biosynthesis, metabolites, and plant sterols in 20 subjects with DS compared to age-matched controls. Here we report that the levels of nearly all lipids and lipoproteins examined are similar to control subjects, suggesting that trisomy 21 does not lead to pronounced general alterations in sterol lipid metabolism. However, the levels of serum brassicasterol were markedly reduced in DS subjects.

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Kazłowska, Katarzyna, Hong-Ting Victor Lin, Shun-Hsien Chang, and Guo-Jane Tsai. "In VitroandIn VivoAnticancer Effects of Sterol Fraction from Red AlgaePorphyra dentata." Evidence-Based Complementary and Alternative Medicine 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/493869.

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Porphyra dentata, an edible red macroalgae, is used as a folk medicine in Asia. This study evaluatedin vitroandin vivothe protective effect of a sterol fraction fromP. dentataagainst breast cancer linked to tumor-induced myeloid derived-suppressor cells (MDSCs). A sterol fraction containing cholesterol,β-sitosterol, and campesterol was prepared by solvent fractionation of methanol extract ofP. dentata in silicagel column chromatography. This sterol fractionin vitrosignificantly inhibited cell growth and induced apoptosis in 4T1 cancer cells. Intraperitoneal injection of this sterol fraction at 10 and 25 mg/kg body weight into 4T1 cell-implanted tumor BALB/c mice significantly inhibited the growth of tumor nodules and increased the survival rate of mice. This sterol fraction significantly decreased the reactive oxygen species (ROS) and arginase activity of MDSCs in tumor-bearing mice. Therefore, the sterol fraction fromP. dentatashowed potential for protecting an organism from 4T1 cell-based tumor genesis.

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Jaramillo-Madrid, Ana Cristina, Raffaela Abbriano, Justin Ashworth, Michele Fabris, Mathieu Pernice, and Peter J. Ralph. "Overexpression of Key Sterol Pathway Enzymes in Two Model Marine Diatoms Alters Sterol Profiles in Phaeodactylum tricornutum." Pharmaceuticals 13, no. 12 (2020): 481. http://dx.doi.org/10.3390/ph13120481.

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Sterols are a class of triterpenoid molecules with diverse functional roles in eukaryotic cells, including intracellular signaling and regulation of cell membrane fluidity. Diatoms are a dominant eukaryotic phytoplankton group that produce a wide diversity of sterol compounds. The enzymes 3-hydroxy-3-methyl glutaryl CoA reductase (HMGR) and squalene epoxidase (SQE) have been reported to be rate-limiting steps in sterol biosynthesis in other model eukaryotes; however, the extent to which these enzymes regulate triterpenoid production in diatoms is not known. To probe the role of these two metabolic nodes in the regulation of sterol metabolic flux in diatoms, we independently over-expressed two versions of the native HMGR and a conventional, heterologous SQE gene in the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum. Overexpression of these key enzymes resulted in significant differential accumulation of downstream sterol pathway intermediates in P. tricornutum. HMGR-mVenus overexpression resulted in the accumulation of squalene, cycloartenol, and obtusifoliol, while cycloartenol and obtusifoliol accumulated in response to heterologous NoSQE-mVenus overexpression. In addition, accumulation of the end-point sterol 24-methylenecholesta-5,24(24’)-dien-3β-ol was observed in all P. tricornutum overexpression lines, and campesterol increased three-fold in P. tricornutum lines expressing NoSQE-mVenus. Minor differences in end-point sterol composition were also found in T. pseudonana, but no accumulation of sterol pathway intermediates was observed. Despite the successful manipulation of pathway intermediates and individual sterols in P. tricornutum, total sterol levels did not change significantly in transformed lines, suggesting the existence of tight pathway regulation to maintain total sterol content.

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Journal articles on the topic 'Stenol'

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