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Membrane Sterols

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https://www.readbyqxmd.com/read/28816608/function-of-plasma-membrane-microdomain-associated-proteins-during-legume-nodulation
#1
Zhenzhen Qiao, Marc Libault
Plasma membrane microdomains are plasma membrane sub-compartments enriched in sphingolipids and sterols, and composed by a specific set of proteins. They are involved in recognizing signal molecules, transducing these signals, and controlling endocytosis and exocytosis processes. In a recent study, applying biochemical and microscopic methods, we characterized the soybean GmFWL1 protein, a major regulator of soybean nodulation, as a new membrane microdomain-associated protein. Interestingly, upon rhizobia inoculation of the soybean root system, GmFWL1 and one of its interacting partners, GmFLOT2/4, both translocate to the root hair cell tip, the primary site of interaction and infection between soybean and Rhizobium...
August 17, 2017: Plant Signaling & Behavior
https://www.readbyqxmd.com/read/28794014/iron-affects-ire1-clustering-propensity-and-the-amplitude-of-endoplasmic-reticulum-stress-signaling
#2
Nir Cohen, Michal Breker, Anush Bakunts, Kristina Pesek, Ainara Chas, Josepmaria Argemí, Andrea Orsi, Lihi Gal, Silvia Chuartzman, Yoav Wigelman, Felix Jonas, Peter Walter, Robert Ernst, Tomás Aragón, Eelco van Anken, Maya Schuldiner
The unfolded protein response (UPR) allows cells to adjust secretory pathway capacity according to need. Ire1, the endoplasmic reticulum (ER) stress sensor and central activator of the UPR is conserved from the budding yeast Saccharomyces cerevisiae to humans. Under ER stress conditions, Ire1 clusters into foci that enable optimal UPR activation. To discover factors that affect Ire1 clustering, we performed a high-content screen using a whole-genome yeast mutant library expressing Ire1-mCherry. We imaged the strains following UPR induction and found 154 strains that displayed alterations in Ire1 clustering...
August 9, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28774891/sterol-transporters-at-membrane-contact-sites-regulate-torc1-and-torc2-signaling
#3
Andrew Murley, Justin Yamada, Bradley J Niles, Alexandre Toulmay, William A Prinz, Ted Powers, Jodi Nunnari
Membrane contact sites (MCSs) function to facilitate the formation of membrane domains composed of specialized lipids, proteins, and nucleic acids. In cells, membrane domains regulate membrane dynamics and biochemical and signaling pathways. We and others identified a highly conserved family of sterol transport proteins (Ltc/Lam) localized at diverse MCSs. In this study, we describe data indicating that the yeast family members Ltc1 and Ltc3/4 function at the vacuole and plasma membrane, respectively, to create membrane domains that partition upstream regulators of the TORC1 and TORC2 signaling pathways to coordinate cellular stress responses with sterol homeostasis...
August 3, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28761089/membrane-perfusion-of-hydrophobic-substances-around-channels-embedded-in-the-contact-bubble-bilayer
#4
Masayuki Iwamoto, Shigetoshi Oiki
In fluidic biomembranes, lipids and membrane proteins diffuse restlessly, and lipid compositions change steadily. To mimic dynamic behavior of the biomembranes, a method for introducing rapid changes in the constituents in the lipid bilayer was developed. In contact bubble bilayers (CBB), as a water-in-oil droplet bilayer system, the bilayer hydrophobic interior is contiguous with the bulk oil phase. Making use of this geometrical feature as an access route, hydrophobic substances were administered into the bilayer...
July 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28759634/the-role-of-co-opted-escrt-proteins-and-lipid-factors-in-protection-of-tombusviral-double-stranded-rna-replication-intermediate-against-reconstituted-rnai-in-yeast
#5
Nikolay Kovalev, Jun-Ichi Inaba, Zhenghe Li, Peter D Nagy
Reconstituted antiviral defense pathway in surrogate host yeast is used as an intracellular probe to further our understanding of virus-host interactions and the role of co-opted host factors in formation of membrane-bound viral replicase complexes in protection of the viral RNA against ribonucleases. The inhibitory effect of the RNA interference (RNAi) machinery of S. castellii, which only consists of the two-component DCR1 and AGO1 genes, was measured against tomato bushy stunt virus (TBSV) in wild type and mutant yeasts...
July 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28758890/structural-basis-for-plant-plasma-membrane-protein-dynamics-and-organization-into-functional-nanodomains
#6
Julien Gronnier, Jean-Marc Crowet, Birgit Habenstein, Mehmet Nail Nasir, Vincent Bayle, Eric Hosy, Matthieu Pierre Platre, Paul Gouguet, Sylvain Raffaele, Denis Martinez, Axelle Grelard, Antoine Loquet, Françoise Simon-Plas, Patricia Gerbeau-Pissot, Christophe Der, Emmanuelle M Bayer, Yvon Jaillais, Magali Deleu, Véronique Germain, Laurence Lins, Sébastien Mongrand
Plasma Membrane is the primary structure for adjusting to ever changing conditions. PM sub-compartmentalization in domains is thought to orchestrate signaling. Yet, mechanisms governing membrane organization are mostly uncharacterized. The plant-specific REMORINs are proteins regulating hormonal crosstalk and host invasion. REMs are the best-characterized nanodomain markers via an uncharacterized moiety called REMORIN C-terminal Anchor. By coupling biophysical methods, super-resolution microscopy and physiology, we decipher an original mechanism regulating the dynamic and organization of nanodomains...
July 31, 2017: ELife
https://www.readbyqxmd.com/read/28749675/differential-interaction-of-synthetic-glycolipids-with-biomimetic-plasma-membrane-lipids-correlates-with-plant-biological-response
#7
Mehmet Nail Nasir, Laurence Lins, Jean-Marc Crowet, Marc Ongena, Stephan Dorey, Sandrine Dhondt-Cordelier, Christophe Clément, Sandrine Bouquillon, Arnaud Haudrechy, Catherine Sarazin, Marie-Laure Fauconnier, Katherine Nott, Magali Deleu
Natural and synthetic amphiphilic molecules including lipopeptides, lipopolysaccharides and glycolipids are able to induce defense mechanisms in plants. In the present work, the perception of two synthetic C14 rhamnolipids, namely Alk-RL and Ac-RL, differing only at the level of the lipid tail terminal group, have been investigated using biological and biophysical approaches. We showed that Alk-RL induces a stronger early signaling response in tobacco cell suspensions than does Ac-RL. The interactions of both synthetic RLs with simplified biomimetic membranes were further analyzed using experimental and in silico approaches...
July 27, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28749007/reactive-oxygen-species-as-mediators-of-sperm-capacitation-and-pathological-damage
#8
REVIEW
R J Aitken
Oxidative stress plays a major role in the life and death of mammalian spermatozoa. These gametes are professional generators of reactive oxygen species (ROS), which appear to derive from three potential sources: sperm mitochondria, cytosolic L-amino acid oxidases, and plasma membrane nicotinamide adenine dinucleotide phosphate oxidases. The oxidative stress created via these sources appears to play a significant role in driving the physiological changes associated with sperm capacitation through the stimulation of a cyclic adenosine monophosphate/Protein kinase A phosphorylation cascade, including the activation of Extracellular signal regulated kinase-like proteins, massive up-regulation of tyrosine phosphorylation in the sperm tail, as well as the induction of sterol oxidation...
July 27, 2017: Molecular Reproduction and Development
https://www.readbyqxmd.com/read/28747907/membrane-phosphoproteomics-of-yeast-early-response-to-acetic-acid-role-of-hrk1-kinase-and-lipid-biosynthetic-pathways-in-particular-sphingolipids
#9
Joana F Guerreiro, Nuno P Mira, Aline X S Santos, Howard Riezman, Isabel Sá-Correia
Saccharomyces cerevisiae response and tolerance to acetic acid is critical in industrial biotechnology and in acidic food and beverages preservation. The HRK1 gene, encoding a protein kinase of unknown function belonging to the "Npr1-family" of kinases known to be involved in the regulation of plasma membrane transporters, is an important determinant of acetic acid tolerance. This study was performed to identify the alterations occurring in yeast membrane phosphoproteome profile during the adaptive early response to acetic acid stress (following 1 h of exposure to a sub-lethal inhibitory concentration; 50 mM at pH 4...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28720840/positioning-of-the-scrambled-receptor-requires-udp-glc-sterol-glucosyltransferase-80b1-in-arabidopsis-roots
#10
Victoria G Pook, Meera Nair, KookHui Ryu, James C Arpin, John Schiefelbein, Kathrin Schrick, Seth DeBolt
The biological function of sterol glucosides (SGs), the most abundant sterol derivatives in higher plants, remains uncertain. In an effort to improve our understanding of these membrane lipids we examined phenotypes exhibited by the roots of Arabidopsis (Arabidopsis thaliana) lines carrying insertions in the UDP-Glc:sterol glucosyltransferase genes, UGT80A2 and UGT80B1. We show that although ugt80A2 mutants exhibit significantly lower levels of total SGs they are morphologically indistinguishable from wild-type plants...
July 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28710641/a-ligand-binding-assay-to-measure-the-affinity-and-specificity-of-sterol-binding-proteins-in-vitro
#11
Rabih Darwiche, Roger Schneiter
Sterols are major constituents of the plasma membrane of eukaryotic cells and serve as a precursor for several classes of signaling molecules, including steroids and hydroxy sterols. They maintain the functionality and permeability barrier of the plasma membrane through lipid-lipid and lipid-protein interactions. The S. cerevisiae pathogen-related yeast proteins 1, 2, and 3 (Pry) belong to a large protein superfamily known as CAP/SCP/TAPS. Members of this superfamily have been implicated in a wide variety of processes, including immune defense in mammals and plants, pathogen virulence, sperm maturation and fertilization, venom toxicity, and prostate and brain cancer...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28706527/localization-of-sphingolipid-enriched-plasma-membrane-regions-and-long-chain-base-composition-during-mature-fruit-abscission-in-olive
#12
Maria C Parra-Lobato, Miguel A Paredes, Juana Labrador, Mariana Saucedo-García, Marina Gavilanes-Ruiz, Maria C Gomez-Jimenez
Sphingolipids, found in membranes of eukaryotic cells, have been demonstrated to carry out functions in various processes in plant cells. However, the roles of these lipids in fruit abscission remain to be determined in plants. Biochemical and fluorescence microscopy imaging approach has been adopted to investigate the accumulation and distribution of sphingolipids during mature-fruit abscission in olive (Olea europaea L. cv. Picual). Here, a lipid-content analysis in live protoplasts of the olive abscission zone (AZ) was made with fluorescent dyes and lipid analogs, particularly plasma membrane sphingolipid-enriched domains, and their dynamics were investigated in relation to the timing of mature-fruit abscission...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28696297/mtorc1-activates-srebp-2-by-suppressing-cholesterol-trafficking-to-lysosomes-in-mammalian-cells
#13
Walaa Eid, Kristin Dauner, Kevin C Courtney, AnneMarie Gagnon, Robin J Parks, Alexander Sorisky, Xiaohui Zha
mTORC1 is known to activate sterol regulatory element-binding proteins (SREBPs) including SREBP-2, a master regulator of cholesterol synthesis. Through incompletely understood mechanisms, activated mTORC1 triggers translocation of SREBP-2, an endoplasmic reticulum (ER) resident protein, to the Golgi where SREBP-2 is cleaved to translocate to the nucleus and activate gene expression for cholesterol synthesis. Low ER cholesterol is a well-established trigger for SREBP-2 activation. We thus investigated whether mTORC1 activates SREBP-2 by reducing cholesterol delivery to the ER...
July 25, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28691419/circulating-pcsk9-over-srebp-2-expression-affects-serum-ldl-and-cholesterol-levels
#14
Asghar Mohammadi, Mohamad Shabani, Faezeh Naseri, Bita Hosseni, Elham Soltanmohammadi, Sadegh Piran, Mohammad Najafi
BACKGROUND: Cholesterol homeostasis is dependent upon sterol regulation element binding protein2 (SREBP-2) regulatory system and plasma proprotein convertase subtilin/kexin type 9 (PCSK9) function. Furthermore, many studies have reported that cellular membrane LDLR level is related to the function of these proteins. OBJECTIVES: The aim of this study was to investigate the association of lipid profile with circulating PCSK9 protein value and SREBP-2 expression level in normal subjects...
June 27, 2017: Advances in Clinical and Experimental Medicine: Official Organ Wroclaw Medical University
https://www.readbyqxmd.com/read/28667115/cgmed3-changes-membrane-sterol-composition-to-help-candida-glabrata-tolerate-low-ph-stress
#15
Xiaobao Lin, Yanli Qi, Dongni Yan, Hui Liu, Xiulai Chen, Liming Liu
Candida glabrata is a promising microorganism for organic acid production. The present study aimed to investigate the role of Mediator complex subunit 3 (CgMed3p) in protecting C. glabrata at low pH conditions. To this end, the genes CgMED3A and CgMED3B were deleted, resulting in the double deletion Cgmed3ABΔ strain. Final biomass and cell viability of Cgmed3ABΔ decreased by 64.5% and 35.8%, respectively, compared to the wild-type at pH 2.0. In addition, lack of CgMed3ABp resulted in selective repression of a subset of genes in the lipid biosynthesis and metabolism pathways...
June 30, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28666916/emerging-roles-for-conjugated-sterols-in-plants
#16
REVIEW
Albert Ferrer, Teresa Altabella, Montserrat Arró, Albert Boronat
In plants, sterols are found in free form (free sterols, FSs) and conjugated as steryl esters (SEs), steryl glycosides (SGs) and acyl steryl glycosides (ASGs). Conjugated sterols are ubiquitously found in plants but their relative contents highly differ among species and their profile may change in response to developmental and environmental cues. SEs play a central role in membrane sterol homeostasis and also represent a storage pool of sterols in particular plant tissues. SGs and ASGs are main components of the plant plasma membrane (PM) that specifically accumulate in lipid rafts, PM microdomains known to mediate many relevant cellular processes...
July 2017: Progress in Lipid Research
https://www.readbyqxmd.com/read/28664184/microrna-29-mediates-a-novel-negative-feedback-loop-to-regulate-scap-srebp-1-and-lipid-metabolism
#17
Peng Ru, Deliang Guo
The membrane-bound transcription factors, SREBPs (sterol regulatory element-binding proteins), play a central role in regulating lipid metabolism. The transcriptional activation of SREBPs requires the key protein SCAP (SREBP-cleavage activating protein) to translocate their precursors from the endoplasmic reticulum to the Golgi for subsequent proteolytic activation, a process tightly regulated by a cholesterol-mediated negative feedback loop. Our previous work showed that the SCAP/SREBP-1 pathway is significantly upregulated in human glioblastoma (GBM), the most deadly brain cancer, and that glucose-mediated N-glycosylation of SCAP is a prerequisite step for SCAP/SREBP trafficking...
2017: RNA & Disease
https://www.readbyqxmd.com/read/28663788/using-spectral-decomposition-of-the-signals-from-laurdan-derived-probes-to-evaluate-the-physical-state-of-membranes-in-live-cells
#18
Serge Mazeres, Farzad Fereidouni, Etienne Joly
Background: We wanted to investigate the physical state of biological membranes in live cells under the most physiological conditions possible. Methods: For this we have been using laurdan, C-laurdan or M-laurdan to label a variety of cells, and a biphoton microscope equipped with both a thermostatic chamber and a spectral analyser. We also used a flow cytometer to quantify the 450/530 nm ratio of fluorescence emissions by whole cells. Results: We find that using all the information provided by spectral analysis to perform spectral decomposition dramatically improves the imaging resolution compared to using just two channels, as commonly used to calculate generalized polarisation (GP)...
2017: F1000Research
https://www.readbyqxmd.com/read/28658622/lanosterol-modulates-tlr4-mediated-innate-immune-responses-in-macrophages
#19
Elisa Araldi, Marta Fernández-Fuertes, Alberto Canfrán-Duque, Wenwen Tang, Gary W Cline, Julio Madrigal-Matute, Jordan S Pober, Miguel A Lasunción, Dianqing Wu, Carlos Fernández-Hernando, Yajaira Suárez
Macrophages perform critical functions in both innate immunity and cholesterol metabolism. Here, we report that activation of Toll-like receptor 4 (TLR4) in macrophages causes lanosterol, the first sterol intermediate in the cholesterol biosynthetic pathway, to accumulate. This effect is due to type I interferon (IFN)-dependent histone deacetylase 1 (HDAC1) transcriptional repression of lanosterol-14α-demethylase, the gene product of Cyp51A1. Lanosterol accumulation in macrophages, because of either treatment with ketoconazole or induced conditional disruption of Cyp51A1 in mouse macrophages in vitro, decreases IFNβ-mediated signal transducer and activator of transcription (STAT)1-STAT2 activation and IFNβ-stimulated gene expression...
June 27, 2017: Cell Reports
https://www.readbyqxmd.com/read/28655854/the-effect-of-sterol-structure-upon-clathrin-mediated-and-clathrin-independent-endocytosis
#20
Ji Hyun Kim, Ashutosh Singh, Maurizio Del Poeta, Deborah A Brown, Erwin London
Ordered lipid domains (rafts) in plasma membranes have been hypothesized to participate in endocytosis based on inhibition of endocytosis by removal or sequestration of cholesterol. To more carefully investigate the role of the sterol in endocytosis, we used a substitution strategy to replace cholesterol with sterols that show various raft-forming abilities and chemical structures. Both clathrin-mediated endocytosis of transferrin and clathrin-independent endocytosis of clustered placental alkaline phosphatase were measured...
August 15, 2017: Journal of Cell Science
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