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Membrane Sterols

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https://www.readbyqxmd.com/read/28720840/positioning-of-the-scrambled-receptor-requires-udp-glc-sterol-glucosyltransferase-80b1-in-arabidopsis-roots
#1
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
#2
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
#3
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
#4
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 10, 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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
JiHyun Kim, Ashutosh Singh, Maurizio DelPoeta, 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 having various raft-forming abilities and chemical structures. Both clathrin-mediated endocytosis of transferrin and clathrin-independent endocytosis of clustered placental alkaline phosphatase were measured...
June 27, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28649260/tomato-udp-glucose-sterol-glycosyltransferases-a-family-of-developmental-and-stress-regulated-genes-that-encode-cytosolic-and-membrane-associated-forms-of-the-enzyme
#12
Karla Ramirez-Estrada, Nídia Castillo, Juan A Lara, Monserrat Arró, Albert Boronat, Albert Ferrer, Teresa Altabella
Sterol glycosyltransferases (SGTs) catalyze the glycosylation of the free hydroxyl group at C-3 position of sterols to produce sterol glycosides. Glycosylated sterols and free sterols are primarily located in cell membranes where in combination with other membrane-bound lipids play a key role in modulating their properties and functioning. In contrast to most plant species, those of the genus Solanum contain very high levels of glycosylated sterols, which in the case of tomato may account for more than 85% of the total sterol content...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28646165/selective-inhibition-of-sterolo-acyltransferase-1-isozyme-by-beauveriolide-iii-in-intact-cells
#13
Taichi Ohshiro, Keisuke Kobayashi, Mio Ohba, Daisuke Matsuda, Lawrence L Rudel, Takashi Takahashi, Takayuki Doi, Hiroshi Tomoda
Beauveriolide III (BeauIII) inhibited sterol O-acyltransferases 1 and 2 (SOAT1 and SOAT2), which are endoplasmic reticulum (ER) membrane proteins, in an enzyme-based assay, and selectively inhibited SOAT1 in a cell-based assay using SOAT1-/SOAT2-CHO cells. This discrepancy in SOAT inhibition by BeauIII was investigated. In the enzyme-based assay, BeauIII inhibited SOAT1 and SOAT2 to a similar extent using microsomes prepared from cells disrupted under the strongest sonication condition. In semi-intact SOAT1-/SOAT2-CHO cells prepared by a treatment with digitonin (plasma membrane permeabilized), BeauIII selectively inhibited SOAT1 (IC50; 5...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28642044/crossregulation-between-the-insertion-of-hexadecylphosphocholine-miltefosine-into-lipid-membranes-and-their-rheology-and-lateral-structure
#14
Yenisleidy de Las Mercedes Zulueta Díaz, María Laura Fanani
Hexadecylphosphocholine (HePC, miltefosine) is an alkylphospholipid used clinically for the topical treatment of cancer and against leishmaniasis. The mechanism of action of HePC, not yet elucidated, involves its insertion into the plasma membrane, affecting lipid homeostasis. It has also been proposed that HePC directly affects lipid raft stability and function in cell membranes. The present work deals with two main questions in the understanding of the action of HePC: the bases for membrane selectivity and as a membrane perturbator agent...
June 20, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28640190/trans-cinnamic-and-chlorogenic-acids-affect-the-secondary-metabolic-profiles-and-ergosterol-biosynthesis-by-fusarium-culmorum-and-f-graminearum-sensu-stricto
#15
Tomasz Kulik, Kinga Stuper-Szablewska, Katarzyna Bilska, Maciej Buśko, Anna Ostrowska-Kołodziejczak, Dariusz Załuski, Juliusz Perkowski
Plant-derived compounds limiting mycotoxin contamination are currently of major interest in food and feed production. However, their potential application requires an evaluation of their effects on fungal secondary metabolism and membrane effects. In this study, different strains of Fusarium culmorum and F. graminearum sensu stricto were exposed to trans-cinnamic and chlorogenic acids on solid YES media. Fusaria produced phenolic acids, whose accumulation was lowered by exogenous phenolic compounds. In addition, fungi reduced exogenous phenolic acids, leading either to their conversion or degradation...
June 22, 2017: Toxins
https://www.readbyqxmd.com/read/28624282/effect-of-endoplasmic-reticulum-stress-on-metabolic-and-stress-signaling-and-kidney-specific-functions-in-madin-darby-bovine-kidney-cells
#16
E Chiappisi, R Ringseis, K Eder, D K Gessner
Recent studies demonstrated induction of endoplasmic reticulum (ER) stress in tissues of cows after parturition, but knowledge about the effect of ER stress on important cellular processes, such as critical signaling and metabolic pathways, in cattle is scarce. Thus, the present study aimed to investigate the effect of ER stress induction on nuclear factor-κB (NF-κB), nuclear factor E2-related factor 2 (Nrf2), and sterol regulatory element-binding protein (SREBF1) pathway in Madin-Darby bovine kidney (MDBK) cells, a widely used in vitro model in ruminant research...
June 14, 2017: Journal of Dairy Science
https://www.readbyqxmd.com/read/28611746/adaptations-to-high-salt-in-a-halophilic-protist-differential-expression-and-gene-acquisitions-through-duplications-and-gene-transfers
#17
Tommy Harding, Andrew J Roger, Alastair G B Simpson
The capacity of halophiles to thrive in extreme hypersaline habitats derives partly from the tight regulation of ion homeostasis, the salt-dependent adjustment of plasma membrane fluidity, and the increased capability to manage oxidative stress. Halophilic bacteria, and archaea have been intensively studied, and substantial research has been conducted on halophilic fungi, and the green alga Dunaliella. By contrast, there have been very few investigations of halophiles that are phagotrophic protists, i.e., protozoa...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28600071/synthetic-antimicrobial-peptides-of-the-halictines-family-disturb-the-membrane-integrity-of-candida-cells
#18
Marie Kodedová, Hana Sychrová
We compared the potency of four derivatives of the antimicrobial peptide halictine-2 against six Candida species. Observed activity was peptide and species specific. Halictines rapidly permeabilized cell membranes and caused the leakage of cytosolic components. Their killing potential was enhanced by the commercial antimicrobial agent octenidine dihydrochloride. The effect on C. glabrata cells did not depend on the activity of Cdr pumps, but was influenced by their lipid composition. The pre-treatment of cells with myriocin, an inhibitor of sphingolipid synthesis, enhanced the peptides' activity, whereas pre-treatment with terbinafine and fluconazole, inhibitors of sterol synthesis, significantly weakened their efficacy...
June 7, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28596107/a-novel-function-for-glucocerebrosidase-as-a-regulator-of-sterylglucoside-metabolism
#19
REVIEW
Hisako Akiyama, Yoshio Hirabayashi
BACKGROUND: Sterols are major cell membrane lipids, and in many organisms they are modified with glucose to generate sterylglucosides. Glucosylation dramatically changes the functional properties of sterols. The formation of sterylglucosides from sterols in plants, fungi, and bacteria uses UDP-glucose as a glucose donor. By contrast, sterylglucoside biosynthesis in mammals is catalyzed by the transglucosylation activity of glucocerebrosidases, with glucosylceramide acting as the glucose donor...
June 6, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28595398/simulations-of-simple-linoleic-acid-containing-lipid-membranes-and-models-for-the-soybean-plasma-membranes
#20
Xiaohong Zhuang, Anna Ou, Jeffery B Klauda
The all-atom CHARMM36 lipid force field (C36FF) has been tested with saturated, monounsaturated, and polyunsaturated lipids; however, it has not been validated against the 18:2 linoleoyl lipids with an unsaturated sn-1 chain. The linoleoyl lipids are common in plants and the main component of the soybean membrane. The lipid composition of soybean plasma membranes has been thoroughly characterized with experimental studies. However, there is comparatively less work done with computational modeling. Our molecular dynamics (MD) simulation results show that the pure linoleoyl lipids, 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine (18:0/18:2) and 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (di-18:2), agree very well with the experiments, which demonstrates the accuracy of the C36FF for the computational study of soybean membranes...
June 7, 2017: Journal of Chemical Physics
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