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Membrane Sterols

Siou-Huei Wang, Han-Jen Lin, Yuan-Yu Lin, Yu-Jen Chen, Yu-Hui Pan, Cheng-Ting Tung, Harry John Mersmann, Shih-Torng Ding
During avian embryonic development, endodermal epithelial cells (EECs) absorb yolk through the yolk sac membrane. Sterol O-acyltransferase (SOAT) is important for esterification and yolk lipid utilization during development. Because the major enzyme for yolk sac membrane cholesteryl ester synthesis is SOAT1, we cloned the avian SOAT1 promoter and elucidated the cellular functions of SOAT1. Treatments with either glucagon, isobutylmethylxanthine (IBMX), an adenylate cyclase activator (forskolin), a cAMP analog (dibutyryl-cAMP), or a low glucose concentration all increased SOAT1 mRNA accumulation in EECs from Japanese quail, suggesting that SOAT1 is regulated by nutrients and hormones through a cAMP-dependent pathway...
2017: PloS One
Matthew R Elkins, Jonathan K Williams, Martin D Gelenter, Peng Dai, Byungsu Kwon, Ivan V Sergeyev, Bradley L Pentelute, Mei Hong
The influenza M2 protein not only forms a proton channel but also mediates membrane scission in a cholesterol-dependent manner to cause virus budding and release. The atomic interaction of cholesterol with M2, as with most eukaryotic membrane proteins, has long been elusive. We have now determined the cholesterol-binding site of the M2 protein in phospholipid bilayers using solid-state NMR spectroscopy. Chain-fluorinated cholesterol was used to measure cholesterol proximity to M2 while sterol-deuterated cholesterol was used to measure bound-cholesterol orientation in lipid bilayers...
November 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
M-Ángeles Curto, Sandra Moro, Francisco Yanguas, Carmen Gutiérrez-González, M-Henar Valdivieso
Dni1 and Dni2 facilitate cell fusion during mating. Here, we show that these proteins are interdependent for their localization in a plasma membrane subdomain, which we have termed the mating fusion domain. Dni1 compartmentation in the domain is required for cell fusion. The contribution of actin, sterol-dependent membrane organization, and Dni2 to this compartmentation was analysed, and the results showed that Dni2 plays the most relevant role in the process. In turn, the Dni2 exit from the endoplasmic reticulum depends on Dni1...
November 13, 2017: Cellular and Molecular Life Sciences: CMLS
Spencer T Behmer
Insects cannot synthesize sterols de novo, but like all eukaryotes they use them as cell membrane inserts where they influence membrane fluidity and rigidity. They also use a small amount for metabolic purposes, most notably as essential precursors for steroid hormones. It has been a long-held view that most insects require a small amount of specific sterol (often cholesterol) for metabolic purposes, but for membrane purposes (where the bulk of sterols are used) specificity in sterol structure was less important...
October 2017: Current Opinion in Insect Science
Takashi Hirama, Stella M Lu, Jason G Kay, Masashi Maekawa, Michael M Kozlov, Sergio Grinstein, Gregory D Fairn
The plasma membrane is uniquely enriched in phosphatidylserine (PtdSer). This anionic phospholipid is restricted almost exclusively to the inner leaflet of the plasmalemma. Because of their high density, the headgroups of anionic lipids experience electrostatic repulsion that, being exerted asymmetrically, is predicted to favor membrane curvature. We demonstrate that cholesterol limits this repulsion and tendency to curve. Removal of cholesterol or insertion of excess PtdSer increases the charge density of the inner leaflet, generating foci of enhanced charge and curvature where endophilin and synaptojanin are recruited...
November 9, 2017: Nature Communications
Elena Ermakova, Yuriy Zuev
Cell membranes are complex multicomponent systems consisting of thousands of different lipids with numerous embedded membrane proteins and many types of sterols. We used all-atom and coarse-grained molecular dynamics simulations to study the structural and dynamical properties of phospholipid bilayers containing four types of phospholipids and different amount of ergosterol, main sterol component in the fungal membranes. To characterize the influence of ergosterol on the membrane properties we analyzed the surface area per lipid, bilayer thickness, area compressibility modulus, mass density profiles, deuterium order parameters, and lateral diffusion coefficients...
November 6, 2017: Chemistry and Physics of Lipids
Mehran Shaghaghi, Amir Keyvanloo, Zhaohua Huang, Francis C Szoka, Jenifer L Thewalt
We report here the first exploration of the nature of the hydrophobic region of bilayer membranes formed from sterol modified phospholipids [Huang, Z.; Szoka, F. C., Sterol-Modified Phospholipids: Cholesterol and Phospholipid Chimeras with Improved Biomembrane Properties. J. Am. Chem. Soc. 2008, 130 (46), 15702-15712] & [Ding, J.; Starling, A. P.; East, J.M.; Lee, A. G., Binding Sites for Cholesterol on Ca(2+)-ATPase Studied by using a Cholesterol-containing Phospholipid. Biochemistry. 1994, 33(16), 4974-4979]...
November 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Jin-Feng Shi, Yu-Kun Li, Kun Ren, Yuan-Jie Xie, Wei-Dong Yin, Zhong-Cheng Mo
The Sertoli cell, which is the supporting cell of spermatogenesis, has an important role in the endocrine and paracrine control of spermatogenesis. Functionally, it provides the cells of the seminiferous epithelium with nutrition, conveys mature spermatids to the lumen of seminiferous tubules, secretes androgen‑binding protein and interacts with endocrine Leydig cells. In addition, the levels of cholesterol, as well as its intermediates, vary greatly between nongonadal tissues and the male reproductive system...
November 7, 2017: Molecular Medicine Reports
Brittany M Johnson, Russell A DeBose-Boyd
Accelerated ubiquitination and subsequent endoplasmic reticulum (ER)-associated degradation (ERAD) constitute one of several mechanisms for feedback control of HMG CoA reductase, the rate-limiting enzyme in synthesis of cholesterol and nonsterol isoprenoids. This ERAD is initiated by the accumulation of certain sterols in ER membranes, which trigger binding of reductase to ER membrane proteins called Insigs. Insig-associated ubiquitin ligases facilitate ubiquitination of reductase, marking the enzyme for extraction across the ER membrane through a reaction that is augmented by nonsterol isoprenoids...
October 28, 2017: Seminars in Cell & Developmental Biology
George Kluck, Karla C Régis, Nuccia N T De Cicco, Lívia Silva-Cardoso, Miria G Pereira, Patrícia Fampa, Alessandra C Chagas-Lima, Alexandre Romeiro, Narcisa L Cunha-Silva, Georgia C Atella
Lipid uptake and metabolism by trypanosomatid parasites from vertebrate host blood have been well established in the literature. However, there is a lack of knowledge regarding the same aspects concerning the parasites that cross the hemolymph of their invertebrate hosts. We have investigated the lipid composition and metabolism of the insect trypanosomatid Herpetomonas muscarum by (3)H- palmitic acid and phosphate ((32)Pi) and the parasite interaction with Lipophorin (Lp) the main lipid carrying protein of insect hemolymph...
November 1, 2017: Parasitology International
Cheng-Hsiu Lin, Yueh-Hsiung Kuo, Chun-Ching Shih
This study was designed to investigate the antidiabetic and antihyperlipidemic effects and mechanisms of eburicoic acid (TRR); one component of Antrodia camphorata in vitro and in an animal model for 14 weeks. Expression levels of membrane glucose transporter type 4 (GLUT4); phospho-5'-adenosine monophosphate-activated protein kinase (AMPK)/total AMPK; and phospho-Akt/total-Akt in insulin-resistant C2C12 myotube cells were significantly decreased by palmitate; and such decrease was prevented and restored by TRR at different concentrations...
November 2, 2017: International Journal of Molecular Sciences
A G Dos Santos, J T Marquês, A C Carreira, I R Castro, A S Viana, M-P Mingeot-Leclercq, R F M de Almeida, L C Silva
Nystatin (Nys) is a pore forming broad-spectrum and efficient antifungal drug with significant toxicity in mammalian organisms. In order to develop a non-toxic and more effective Nys formulation, its molecular mechanism of action at the cell membrane needs to be better understood. It is widely accepted that Nys activity and toxicity depend on the presence and type of membrane sterols. Taking advantage of multiple biophysical methodologies, we now show that the formation and stabilization of Nys aqueous pores, which are associated with Nys cytotoxicity, occur in the absence of membrane sterols...
November 3, 2017: Physical Chemistry Chemical Physics: PCCP
Ruochen Du, Jiandong Liu, Panpan Sun, Hongquan Li, Jinsheng Wang
Botanical fungicides comprise attractive alternatives to chemical fungicides because of their environmental compatibility. Flavonoids extracted from Tagetes erecta L. have an inhibitory effect on fusarium wilt in watermelons caused by Fusarium oxysporum f. sp. niveum (FON). In this study, we synthesized one of these flavonoids, 2,5-dicyclopentylidene cyclopentanone (Tagetes erecta L. fungicide (TEF)) and assessed its activity against FON. In vitro, TEF inhibited FON growth and killed FON cells directly. TEF also affected FON cell physiology and mycelial structure...
October 31, 2017: Scientific Reports
Wenjuan Zhang, S Paige Taylor, Hayley A Ennis, Kimberly N Forlenza, Ivan Duran, Bing Li, Jorge A Ortiz Sanchez, Lisette Nevarez, Deborah A Nickerson, Michael Bamshad, Ralph S Lachman, Deborah Krakow, Daniel H Cohn
Defects in the biosynthesis and/or function of primary cilia cause a spectrum of disorders collectively referred to as ciliopathies. A subset of these disorders is distinguished by profound abnormalities of the skeleton that include a long narrow chest with markedly short ribs, extremely short limbs, and polydactyly. These include the perinatal lethal short-rib polydactyly syndromes (SRPS) and the less severe asphyxiating thoracic dystrophy (ATD), Ellis van Creveld (EVC) syndrome and cranioectodermal dysplasia (CED) phenotypes...
October 25, 2017: Human Mutation
Li Zhang, Prashant Rajbhandari, Christina Priest, Jaspreet Sandhu, Xiaohui Wu, Ryan Temel, Antonio Castrillo, Thomas Q de Aguiar Vallim, Tamer Sallam, Peter Tontonoz
Cholesterol homeostasis is maintained through concerted action of the SREBPs and LXRs. Here, we report that RNF145, a previously uncharacterized ER membrane ubiquitin ligase, participates in crosstalk between these critical signaling pathways. RNF145 expression is induced in response to LXR activation and high-cholesterol diet feeding. Transduction of RNF145 into mouse liver inhibits the expression of genes involved in cholesterol biosynthesis and reduces plasma cholesterol levels. Conversely, acute suppression of RNF145 via shRNA-mediated knockdown, or chronic inactivation of RNF145 by genetic deletion, potentiates the expression of cholesterol biosynthetic genes and increases cholesterol levels both in liver and plasma...
October 25, 2017: ELife
Benjamin B Johnson, Mariana Breña, Juan Anguita, Alejandro P Heuck
Cholesterol distribution in the cell is maintained by both vesicular and non-vesicular sterol transport. Non-vesicular transport is mediated by the interaction of membrane-embedded cholesterol and water-soluble proteins. Small changes to the lipid composition of the membrane that do not change the total cholesterol content, can significantly affect how cholesterol interacts with other molecules at the surface of the membrane. The cholesterol-dependent cytolysin Perfringolysin O (PFO) constitutes a powerful tool to detect cholesterol in membranes, and the use of PFO-based probes has flourished in recent years...
October 23, 2017: Scientific Reports
George Gachumi, Anas El-Aneed
Plant sterols (phytosterols) are important structural components of plant cellular membranes, and they play a major role during development and metabolism. They have health-associated benefits, especially in lowering blood cholesterol levels. Because of their many health claims, there is a growing interest in their analysis. Although various analytical strategies have been employed in analyzing phytosterols, chromatography linked to mass spectrometry (MS) is superior due to its sensitivity. Furthermore, specificity and selectivity are enhanced by utilizing tandem mass spectrometry (MS/MS)...
November 8, 2017: Journal of Agricultural and Food Chemistry
Laetitia Fouillen, Lilly Maneta-Peyret, Patrick Moreau
Plant ER membranes are the major site of biosynthesis of several lipid families (phospholipids, sphingolipids, neutral lipids such as sterols and triacylglycerols). The structural diversity of lipids presents considerable challenges to comprehensive lipid analysis. This chapter will briefly review the various biosynthetic pathways and will detail several aspects of the lipid analysis: lipid extraction, handling, separation, detection, identification, and data presentation. The different tools/approaches used for lipid analysis will also be discussed in relation to the studies to be carried out on lipid metabolism and function...
2018: Methods in Molecular Biology
Maria Filek, Elżbieta Rudolphi-Skórska, Apolonia Sieprawska, Miroslav Kvasnica, Anna Janeczko
Steroids constitute one of the most important groups of compounds of regulatory properties both in the animal and plant kingdom. In plants, steroids such as brassinosteroids or progesterone, by binding to protein receptors in cell membranes, regulate growth and initiate processes leading to increased tolerance to stress conditions. Due to their structural similarities to sterols, these steroids may also directly interact with cellular membranes. Our aim was to determine the changes of the structural parameters of lipid membranes under the influence of hydrophobic steroid compounds, i...
October 10, 2017: Steroids
Richard J Smindak, Lindsay A Heckle, Supraja S Chittari, Marissa A Hand, Dylan M Hyatt, Grace E Mantus, William A Sanfelippo, Keith G Kozminski
Polarized exocytosis is an essential process in many organisms and cell types for proper cell division or functional specialization. Previous studies established that Oxysterol Binding Protein (OSBP) homologues in S. cerevisiae, which comprise the Osh protein family, are necessary for efficient polarized exocytosis by supporting a late step post-Golgi. We define that step as the docking of a specific sub-population of exocytic vesicles with the plasma membrane. In the absence of other Osh proteins, Osh4p can support this process in a manner dependent upon two lipid ligands, PI4P and sterol...
October 9, 2017: Journal of Cell Science
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