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Membrane Sterols

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https://www.readbyqxmd.com/read/28526017/the-effect-of-hypoxia-on-the-lipidome-of-recombinant-pichia-pastoris
#1
Núria Adelantado, Pablo Tarazona, Karlheinz Grillitsch, Xavier García-Ortega, Sergi Monforte, Francisco Valero, Ivo Feussner, Günther Daum, Pau Ferrer
BACKGROUND: Cultivation of recombinant Pichia pastoris (Komagataella sp.) under hypoxic conditions has a strong positive effect on specific productivity when the glycolytic GAP promoter is used for recombinant protein expression, mainly due to upregulation of glycolytic conditions. In addition, transcriptomic analyses of hypoxic P. pastoris pointed out important regulation of lipid metabolism and unfolded protein response (UPR). Notably, UPR that plays a role in the regulation of lipid metabolism, amino acid metabolism and protein secretion, was found to be upregulated under hypoxia...
May 19, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28524381/antifungal-activity-of-gallic-acid-in-vitro-and-in-vivo
#2
Zhi-Jian Li, Meng Liu, Gulina Dawuti, Qin Dou, Yu Ma, Heng-Ge Liu, Silafu Aibai
Gallic acid (GA) is a polyphenol natural compound found in many medicinal plant species, including pomegranate rind (Punica granatum L.), and has been shown to have antiinflammatory and antibacterial properties. Pomegranate rind is used to treat bacterial and fungal pathogens in Uyghur and other systems of traditional medicine, but, surprisingly, the effects of GA on antifungal activity have not yet been reported. In this study, we aimed to investigate the inhibitory effects of GA on fungal strains both in vitro and in vivo...
May 19, 2017: Phytotherapy Research: PTR
https://www.readbyqxmd.com/read/28510502/the-impact-of-steroidal-glycoalkaloids-on-the-physiology-of-phytophthora-infestans-the-causative-agent-of-potato-late-blight
#3
Paul Dahlin, Marion C Müller, Sophia Ekengren, Lauren S McKee, Vincent Bulone
Steroidal glycoalkaloids (SGAs) are plant secondary metabolites known to be toxic to animals and humans and that have putative roles in defense against pests. The proposed mechanisms of SGA toxicity are sterol-mediated disruption of membranes and inhibition of cholinesterase activity in neurons. It has been suggested that phytopathogenic microorganisms can overcome SGA toxicity by enzymatic deglycosylation of SGAs. Here, we have explored SGA-mediated toxicity toward the invasive oomycete Phytophthora infestans, the causative agent of the late blight disease in potato and tomato, as well as the potential for SGA deglycosylation by this species...
May 16, 2017: Molecular Plant-microbe Interactions: MPMI
https://www.readbyqxmd.com/read/28509379/microbial-eukaryotes-that-lack-sterols
#4
Kiyotaka Takishita, Yoshito Chikaraishi, Goro Tanifuji, Naohiko Ohkouchi, Tetsuo Hashimoto, Katsunori Fujikura, Andrew J Roger
It is widely held that sterols are key cyclic triterpenoid lipids in eukaryotic cell membranes and are synthesized through oxygen-dependent multi-enzyme pathways. However, there are known exceptions-ciliated protozoans, such as Tetrahymena, along with diverse low-oxygen adapted eukaryotes produce, instead of sterols, the cyclic triterpenoid lipid tetrahymanol that does not require molecular oxygen for its biosynthesis. Here, we report that a number of anaerobic microbial eukaryotes (protists) utilize neither sterols nor tetrahymanol in their membranes...
May 16, 2017: Journal of Eukaryotic Microbiology
https://www.readbyqxmd.com/read/28505379/analysis-of-cfb-a-cytokinin-responsive-gene-of-arabidopsis-thaliana-encoding-a-novel-f-box-protein-regulating-sterol-biosynthesis
#5
Wolfram G Brenner, Jan Erik Leuendorf, Anne Cortleven, Laetitia B B Martin, Hubert Schaller, Thomas Schmülling
Protein degradation by the ubiquitin-26S proteasome pathway is important for the regulation of cellular processes, but the function of most F-box proteins relevant to substrate recognition is unknown. We describe the analysis of the gene Cytokinin-induced F-box encoding (CFB, AT3G44326), identified in a meta-analysis of cytokinin-related transcriptome studies as one of the most robust cytokinin response genes. F-box domain-dependent interaction with the E3 ubiquitin ligase complex component ASK1 classifies CFB as a functional F-box protein...
May 12, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28503207/membrane-properties-of-hydroxycholesterols-related-to-the-brain-cholesterol-metabolism
#6
Malte Hilsch, Ivan Haralampiev, Peter Müller, Daniel Huster, Holger A Scheidt
Compared to cholesterol, hydroxycholesterols contain an additional hydroxy group in the alkyl chain and are able to efficiently cross the brain-blood barrier. Therefore, they are responsible for the sterol transfer between brain and circulation. The current study compares the membrane properties of several hydroxycholesterols with those of cholesterol using (2)H NMR spectroscopy, a membrane permeability assay, and fluorescence microscopy experiments. It is shown that hydroxycholesterols do not exert the unique impact on membrane properties characteristic for cholesterol with regard to the influence on lipid chain order, membrane permeability and formation of lateral domains...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28472750/effect-of-the-presence-of-cholesterol-in-the-interfacial-microenvironment-on-the-modulation-of-the-alkaline-phosphatase-activity-during-in-vitro-mineralization
#7
B F Favarin, M A R Andrade, M Bolean, A M S Simão, A P Ramos, M F Hoylaerts, J L Millán, P Ciancaglini
Mineralization of the skeleton starts within cell-derived matrix vesicles (MVs); then, minerals propagate to the extracellular collagenous matrix. Tissue-nonspecific alkaline phosphatase (TNAP) degrades inorganic pyrophosphate (PPi), a potent inhibitor of mineralization, and contributes Pi (Phosphate) from ATP to initiate mineralization. Compared to the plasma membrane, MVs are rich in Cholesterol (Chol) (∼32%) and TNAP, but how Chol influences TNAP activity remains unclear. We have reconstituted TNAP in liposomes of dipalmitoylphosphatidylcholine (DPPC) or dioleoylphosphatidylcholine (DOPC) combined with Chol or its derivatives Cholestenone (Achol) and Ergosterol (Ergo)...
April 26, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28465104/phenanthridin-6-one-derivatives-as-the-first-class-of-non-steroidal-pharmacological-chaperones-for-niemann-pick-disease-type-c1-protein
#8
Hiromitsu Fukuda, Fumika Karaki, Kosuke Dodo, Tomomi Noguchi-Yachide, Minoru Ishikawa, Yuichi Hashimoto, Kenji Ohgane
Niemann-Pick disease type C is a fatal, progressive neurodegenerative disease mostly caused by mutations in Nieamnn-Pick type C1 (NPC1), a late endosomal membrane protein that is essential for intracellular cholesterol transport. The most prevalent mutation, I1061T (Ile to Thr), interferes with the protein folding process. Consequently, mutated but intrinsically functional NPC1 proteins are prematurely degraded via proteasome, leading to loss of NPC1 function. Previously, we reported sterol derivatives as pharmacological chaperones for NPC1, and showed that these derivatives can normalize folding-defective phenotypes of I1061T NPC1 mutant by directly binding to, and stabilizing, the protein...
April 22, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28463579/peroxisomal-acbd4-interacts-with-vapb-and-promotes-er-peroxisome-associations
#9
Joseph L Costello, Inês G Castro, Tina A Schrader, Markus Islinger, Michael Schrader
Cooperation between cellular organelles such as mitochondria, peroxisomes and the ER is essential for a variety of important and diverse metabolic processes. Effective communication and metabolite exchange requires physical linkages between the organelles, predominantly in the form of organelle contact sites. At such contact sites organelle membranes are brought into close proximity by the action of molecular tethers, which often consist of specific protein pairs anchored in the membrane of the opposing organelles...
May 2, 2017: Cell Cycle
https://www.readbyqxmd.com/read/28453654/genomic-evidence-that-methanotrophic-endosymbionts-likely-provide-deep-sea-bathymodiolus-mussels-with-a-sterol-intermediate-in-cholesterol-biosynthesis
#10
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. Based on the stable carbon isotope analyses, it has been suggested that host Bathymodiolus mussels synthesize cholesterol using a sterol intermediate derived from the methanotrophic endosymbionts...
May 1, 2017: Genome Biology and Evolution
https://www.readbyqxmd.com/read/28442766/nanoscale-membrane-domain-formation-driven-by-cholesterol
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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...
July 2017: Phytochemistry
https://www.readbyqxmd.com/read/28402884/interdigitation-between-triglycerides-and-lipids-modulates-surface-properties-of-lipid-droplets
#17
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
#18
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
#19
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
#20
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
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