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Membrane Sterols

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https://www.readbyqxmd.com/read/28453654/genomic-evidence-that-methanotrophic-endosymbionts-likely-provide-deep-sea-bathymodiolus-mussels-with-a-sterol-intermediate-in-cholesterol-biosynthesis
#1
Kiyotaka Takishita, Yoshihiro Takaki, Yoshito Chikaraishi, Tetsuro Ikuta, Genki Ozawa, Takao Yoshida, Naohiko Ohkouchi, Katsunori Fujikura
Sterols are key cyclic triterpenoid lipid components of eukaryotic cellular membranes, which are synthesized through complex multi-enzyme pathways. Similar to most animals, Bathymodiolus mussels, which inhabit deep-sea chemosynthetic ecosystems and harbor methanotrophic and/or thiotrophic bacterial endosymbionts, possess cholesterol as their main sterol. On the basis of stable carbon isotope analyses, it has been suggested that host Bathymodiolus mussels synthesize cholesterol using a sterol intermediate derived from the methanotrophic endosymbionts...
April 26, 2017: Genome Biology and Evolution
https://www.readbyqxmd.com/read/28442766/nanoscale-membrane-domain-formation-driven-by-cholesterol
#2
Matti Javanainen, Hector Martinez-Seara, Ilpo Vattulainen
Biological membranes generate specific functions through compartmentalized regions such as cholesterol-enriched membrane nanodomains that host selected proteins. Despite the biological significance of nanodomains, details on their structure remain elusive. They cannot be observed via microscopic experimental techniques due to their small size, yet there is also a lack of atomistic simulation models able to describe spontaneous nanodomain formation in sufficiently simple but biologically relevant complex membranes...
April 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28431322/xanthohumol-and-8-prenylnaringenin-ameliorate-diabetic-related-metabolic-dysfunctions-in-mice
#3
Raquel Costa, Ilda Rodrigues, Luísa Guardão, Sílvia Rocha-Rodrigues, Carolina Silva, José Magalhães, Manuel Ferreira-de-Almeida, Rita Negrão, Raquel Soares
Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by metabolic disturbances in specific tissues. The present work aimed to analyze the effects of xanthohumol (XN) and 8-prenylnaringenin (8PN), two beer-derived polyphenols, in liver and skeletal muscle lipid and glycolytic metabolism in T2DM mice model. Thirty C57Bl/6 mice were randomly divided into five groups: standard diet (control), high-fat diet (DM), high-fat diet plus ethanol (DM-Ethanol), high-fat diet plus 10 mg/L XN (DM-XN) and high-fat diet plus 10 mg/L 8PN (DM-8PN) during 20 weeks...
April 6, 2017: Journal of Nutritional Biochemistry
https://www.readbyqxmd.com/read/28428001/cholesterol-and-related-sterols-autoxidation
#4
REVIEW
Chiara Zerbinati, Luigi Iuliano
Cholesterol is a unique lipid molecule providing the building block for membranes, hormone, vitamin D and bile acid synthesis. Metabolism of cholesterol involves several enzymes acting on the sterol nucleus or the iso-octyl tail. In the recent years, research interest has been focused on oxysterols, cholesterol derivatives generated by the addition of oxygen to the cholesterol backbone. Oxysterols can be produced enzymatically or by autoxidation. Autoxidation of cholesterol proceeds through type I or type II mechanisms...
April 17, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28416613/hypoxia-inducible-factor-1%C3%AE-activates-insig-2-transcription-for-degradation-of-hmg-coa-reductase-in-the-liver
#5
Seonghwan Hwang, Andrew D Nguyen, Youngah Jo, Luke J Engelking, James Brugarolas, Russell A DeBose-Boyd
Cholesterol synthesis is a highly oxygen-consuming process. As such, oxygen deprivation (hypoxia) limits cholesterol synthesis through incompletely understood mechanisms mediated by the oxygen-sensitive transcription factor hypoxia-inducible factor (HIF)-1α. We show here that HIF-1α links pathways for oxygen sensing and feedback control of cholesterol synthesis in human fibroblasts by directly activating transcription of the INSIG-2 gene. Insig-2 is one of two endoplasmic reticulum (ER) membrane proteins that inhibit cholesterol synthesis by mediating sterol-induced ubiquitination and subsequent ER-associated degradation of the rate-limiting enzyme in the pathway, HMG CoA reductase (HMGCR)...
April 17, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28414811/tissue-expression-profiles-and-transcriptional-regulation-of-elongase-of-very-long-chain-fatty-acid-6-in-bovine-mammary-epithelial-cells
#6
Si Chen, Hua He, Xiaolin Liu
In mammals, very long chain fatty acids (VLCFAs) perform pleiotropic roles in a wide range of biological processes, such as cell membrane formation, cell signal transduction, and endocrine regulation. Beef and milk are abundant of palmitic acid which can be further elongated into stearic acid for synthesizing VLCFAs. Elongase of very long chain fatty acid 6 (ELOVL6) is a rate-limiting enzyme for converting palmitic acid to stearic acid. Consequently, investigating the tissue expression patterns and transcriptional regulation of bovine ELOVL6 can provide new insights into improving the composition of beneficial fats in cattle and expanding the knowledge of transcriptional regulation mechanism among domestic animals...
2017: PloS One
https://www.readbyqxmd.com/read/28407491/uv-c-radiation-increases-sterol-production-in-the-microalga-pavlova-lutheri
#7
Faruq Ahmed, Peer M Schenk
Plant sterols have become well-known to promote cardiovascular health through the reduction of low density lipoprotein cholesterol in the blood. Plant sterols also have anti-inflammatory, anti-cancer, anti-oxidative and anti-atherogenicity activities. Microalgae have the potential to become a useful alternative source of plant sterols with several species reported to have higher concentrations than current commercial ones. In order to increase phytosterol production and optimise culture conditions, the high sterol producer Pavlova lutheri was treated in different dosages (50-250 mJ m(-2)) of UV-C radiation and several concentrations (1-500 μmol/L) of hydrogen peroxide (H2O2) and the sterol contents were quantified for two days after the treatments...
April 10, 2017: Phytochemistry
https://www.readbyqxmd.com/read/28402884/interdigitation-between-triglycerides-and-lipids-modulates-surface-properties-of-lipid-droplets
#8
Amélie Bacle, Romain Gautier, Catherine L Jackson, Patrick F J Fuchs, Stefano Vanni
Intracellular lipid droplets (LDs) are the main cellular site of metabolic energy storage. Their structure is unique inside the cell, with a core of esterified fatty acids and sterols, mainly triglycerides and sterol esters, surrounded by a single monolayer of phospholipids. Numerous peripheral proteins, including several that were previously associated with intracellular compartments surrounded by a lipid bilayer, have been recently shown to target the surface of LDs, but how they are able to selectively target this organelle remains largely unknown...
April 11, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28396711/engineering-plant-membranes-using-droplet-interface-bilayers
#9
N E Barlow, E Smpokou, M S Friddin, R Macey, I R Gould, C Turnbull, A J Flemming, N J Brooks, O Ces, L M C Barter
Droplet interface bilayers (DIBs) have become widely recognised as a robust platform for constructing model membranes and are emerging as a key technology for the bottom-up assembly of synthetic cell-like and tissue-like structures. DIBs are formed when lipid-monolayer coated water droplets are brought together inside a well of oil, which is excluded from the interface as the DIB forms. The unique features of the system, compared to traditional approaches (e.g., supported lipid bilayers, black lipid membranes, and liposomes), is the ability to engineer multi-layered bilayer networks by connecting multiple droplets together in 3D, and the capability to impart bilayer asymmetry freely within these droplet architectures by supplying droplets with different lipids...
March 2017: Biomicrofluidics
https://www.readbyqxmd.com/read/28396346/photoaffinity-labeling-with-cholesterol-analogues-precisely-maps-a-cholesterol-binding-site-in-voltage-dependent-anion-channel-1
#10
Melissa M Budelier, Wayland Wl Cheng, Lucie Bergdoll, Zi-Wei Chen, James W Janetka, Jeff Abramson, Kathiresan Krishnan, Laurel Mydock-McGrane, Douglas F Covey, Julian P Whitelegge, Alex S Evers
Voltage-dependent anion channel-1 (VDAC1) is a highly regulated β-barrel membrane protein that mediates transport of ions and metabolites between the mitochondria and cytosol of the cell. VDAC1 co-purifies with cholesterol and is functionally regulated by cholesterol, among other endogenous lipids. Molecular modeling studies based on NMR observations have suggested five cholesterol-binding sites in VDAC1, but direct experimental evidence for these sites is lacking. Here, to determine the sites of cholesterol binding, we photolabeled purified mouse VDAC1 (mVDAC1) with photoactivatable cholesterol analogues and analyzed the photolabeled sites with both top-down mass spectrometry (MS), and bottom-up MS paired with a clickable, stable isotope labeled tag, FLI-tag...
April 10, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28389479/characterization-of-drosophila-saposin-related-mutants-as-a-model-for-lysosomal-sphingolipid-storage-diseases
#11
Julia Sellin, Heike Schulze, Marie Paradis, Dominic Gosejacob, Cyrus Papan, Andrej Shevchenko, Olympia Ekaterina Psathaki, Achim Paululat, Melanie Thielisch, Konrad Sandhoff, Michael Hoch
Sphingolipidoses are inherited diseases belonging to the class of lysosomal storage diseases (LSDs), which are characterized by the accumulation of indigestible material in the lysosome caused by specific defects in the lysosomal degradation machinery. While some LSDs can be efficiently treated by enzyme replacement therapy (ERT), this is not possible if the nervous system is affected due to the presence of the blood brain barrier. Sphingolipidoses in particular often present as severe, untreatable forms of LSDs with massive sphingolipid and membrane accumulation in lysosomes, neurodegeneration, and very short life expectancy...
April 7, 2017: Disease Models & Mechanisms
https://www.readbyqxmd.com/read/28383996/nfe2l2-nrf2-activity-is-linked-to-mitochondria-and-amp-activated-protein-kinase-signaling-in-cancers-through-mir-181c-mitochondria-encoded-cytochrome-c-oxidase-regulation
#12
Kyeong-Ah Jung, Sujin Lee, Mi-Kyoung Kwak
AIMS: The nuclear factor (erythroid-derived 2)-like 2 (NFE2L2; NFE2L2/NRF2) pathway contributes to the environmental resistance of cancers by enhancing the antioxidant capacity. Here, we explored the potential connection between NFE2L2/NRF2 and mitochondrial function in cancers. RESULTS: Global miRNA expression analysis of HT29 and HCT116 human colon cancer cells identified that NFE2L2/NRF2 silencing upregulated miR-181c through nuclear factor-κB signaling, and this increase was associated with the reduction in mitochondria-encoded cytochrome c oxidase subunit-1 (MT-CO1), a catalytic core subunit of the complex IV of the electron transport chain (ETC)...
April 6, 2017: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/28382456/effect-of-fabp1-scp-2-scp-x-ablation-on-whole-body-and-hepatic-phenotype-of-phytol-fed-male-mice
#13
Danilo Landrock, Sherrelle Milligan, Gregory G Martin, Avery L McIntosh, Kerstin K Landrock, Friedhelm Schroeder, Ann B Kier
Liver fatty acid binding protein (Fabp1) and sterol carrier protein-2/sterol carrier protein-x (SCP-2/SCP-x) genes encode proteins that enhance hepatic uptake, cytosolic transport, and peroxisomal oxidation of toxic branched-chain fatty acids derived from dietary phytol. Since male wild-type (WT) mice express markedly higher levels of these proteins than females, the impact of ablating both genes (TKO) was examined in phytol-fed males. In WT males, high phytol diet alone had little impact on whole body weight and did not alter the proportion of lean tissue mass (LTM) versus fat tissue mass (FTM)...
April 5, 2017: Lipids
https://www.readbyqxmd.com/read/28377508/cholesterol-induced-conformation-changes-in-the-sterol-sensing-domain-of-the-scap-protein-suggest-feedback-mechanism-to-control-cholesterol-synthesis
#14
Yansong Gao, Yulian Zhou, Joseph L Goldstein, Michael S Brown, Arun Radhakrishnan
Scap is a polytopic protein of endoplasmic reticulum (ER) membranes that transports sterol regulatory element-binding proteins to the Golgi complex for proteolytic activation. Cholesterol accumulation in ER membranes prevents Scap transport and decreases cholesterol synthesis. Previously, we provided evidence that cholesterol inhibition is initiated when cholesterol binds to loop 1 of Scap, which projects into the ER lumen. Within cells this binding causes loop 1 to dissociate from loop 7, another luminal Scap loop...
April 3, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28377506/heme-deficiency-sensitizes-yeast-cells-to-oxidative-stress-induced-by-hydroxyurea
#15
Amanpreet Singh, Yong-Jie Xu
Hydroxyurea (HU) has a long history of clinical and scientific use as an antiviral, antibacterial, and antitumor agent. It inhibits ribonucleotide reductase and reversibly arrests cells in S phase. However, high concentrations or prolonged treatment with low doses of HU can cause cell lethality. Although the cytotoxicity of HU may significantly contribute to its therapeutic effects, the underlying mechanisms remain poorly understood. We have previously shown that HU can induce cytokinesis arrest in the erg11-1 mutant of fission yeast, which has a partial defect in the biosynthesis of fungal membrane sterol ergosterol (1)...
April 4, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28377464/stard3-mediates-endoplasmic-reticulum-to-endosome-cholesterol-transport-at-membrane-contact-sites
#16
Léa P Wilhelm, Corinne Wendling, Benoît Védie, Toshihide Kobayashi, Marie-Pierre Chenard, Catherine Tomasetto, Guillaume Drin, Fabien Alpy
StAR-related lipid transfer domain-3 (STARD3) is a sterol-binding protein that creates endoplasmic reticulum (ER)-endosome contact sites. How this protein, at the crossroad between sterol uptake and synthesis pathways, impacts the intracellular distribution of this lipid was ill-defined. Here, by using in situ cholesterol labeling and quantification, we demonstrated that STARD3 induces cholesterol accumulation in endosomes at the expense of the plasma membrane. STARD3-mediated cholesterol routing depends both on its lipid transfer activity and its ability to create ER-endosome contacts...
April 4, 2017: EMBO Journal
https://www.readbyqxmd.com/read/28368351/lipid-raft-regulator-of-plasmodesmal-callose-homeostasis
#17
REVIEW
Arya Bagus Boedi Iswanto, Jae-Yean Kim
Abstract: The specialized plasma membrane microdomains known as lipid rafts are enriched by sterols and sphingolipids. Lipid rafts facilitate cellular signal transduction by controlling the assembly of signaling molecules and membrane protein trafficking. Another specialized compartment of plant cells, the plasmodesmata (PD), which regulates the symplasmic intercellular movement of certain molecules between adjacent cells, also contains a phospholipid bilayer membrane. The dynamic permeability of plasmodesmata (PDs) is highly controlled by plasmodesmata callose (PDC), which is synthesized by callose synthases (CalS) and degraded by β-1,3-glucanases (BGs)...
April 3, 2017: Plants (Basel, Switzerland)
https://www.readbyqxmd.com/read/28365392/effects-of-seaweed-sterols-fucosterol-and-desmosterol-on-lipid-membranes
#18
Ole G Mouritsen, Luis A Bagatolli, Lars Duelund, Olav Garvik, John H Ipsen, Adam Cohen Simonsen
Higher sterols are universally present in large amounts (20-30%) in the plasma membranes of all eukaryotes whereas they are universally absent in prokaryotes. It is remarkable that each kingdom of the eukaryotes has chosen, during the course of evolution, its preferred sterol: cholesterol in animals, ergosterol in fungi and yeast, phytosterols in higher plants, and e.g., fucosterol and desmosterol in algae. The question arises as to which specific properties do sterols impart to membranes and to which extent do these properties differ among the different sterols...
March 30, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28358007/cholesterol-mediated-allosteric-regulation-of-the-mitochondrial-translocator-protein-structure
#19
Garima Jaipuria, Andrei Leonov, Karin Giller, Suresh Kumar Vasa, Łukasz Jaremko, Mariusz Jaremko, Rasmus Linser, Stefan Becker, Markus Zweckstetter
Cholesterol is an important regulator of membrane protein function. However, the exact mechanisms involved in this process are still not fully understood. Here we study how the tertiary and quaternary structure of the mitochondrial translocator protein TSPO, which binds cholesterol with nanomolar affinity, is affected by this sterol. Residue-specific analysis of TSPO by solid-state NMR spectroscopy reveals a dynamic monomer-dimer equilibrium of TSPO in the membrane. Binding of cholesterol to TSPO's cholesterol-recognition motif leads to structural changes across the protein that shifts the dynamic equilibrium towards the translocator monomer...
March 30, 2017: Nature Communications
https://www.readbyqxmd.com/read/28348920/a-new-kinetic-spectrophotometric-method-for-the-quantitation-of-amorolfine
#20
César Soto, Cristian Poza, David Contreras, Jorge Yáñez, Fallon Nacaratte, M Inés Toral
Amorolfine (AOF) is a compound with fungicide activity based on the dual inhibition of growth of the fungal cell membrane, the biosynthesis and accumulation of sterols, and the reduction of ergosterol. In this work a sensitive kinetic and spectrophotometric method for the AOF quantitation based on the AOF oxidation by means of KMnO4 at 30 min (fixed time), pH alkaline, and ionic strength controlled was developed. Measurements of changes in absorbance at 610 nm were used as criterion of the oxidation progress...
2017: Journal of Analytical Methods in Chemistry
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