Showing papers on "Phosphatidylethanolamine published in 2002"
TL;DR: Data suggest that PC, rather than PE and PG, is the majorin vivo substrate of PLDα, and the greater loss of PC and increase in PA in wild-type plants as compared with PLD α-deficient plants may be responsible for destabilizing membrane bilayer structure.
929 citations
TL;DR: As a characteristic myelin lipid, sphingomyelin was mainly constituted by very long chain saturated and monounsaturated fatty acids, and its accretion after birth was dramatic, as myelination advanced, 18:1n‐9 increased markedly in all four glycerophospholipids, predominating in EP, PS, and PC.
Abstract: The fatty acid composition of phosphatidylethanolamine (PE), ethanolamine plasmalogens (EPs), phosphatidylserine (PS), phosphatidylcholine (PC), and sphingomyelin was studied in 22 human forebrains, ranging in age from 26 prenatal weeks to 8 postnatal years. Phospholipids were separated by two-dimensional TLC, and the fatty acid methyl esters studied by capillary column GLC. Docosahexaenoic acid (22:6n-3) increased with age in PE and PC, whereas arachidonic acid (20:4n-6) remained quite constant. In EP, 22:6n-3 increased less markedly than 20:4n-6, adrenic (22:4n-6) and oleic (18:1n-9) acids being the predominant fatty acids during postnatal age. In PS, 18:1n-9 increased dramatically throughout development, and 20:4n-6 and 22:4n-6 increased only until approximately 6 months of age. Although 22:6n-3 kept quite constant during development in PS, its percentage decreased due to the accretion of other polyunsaturated fatty acids (PUFAs). As a characteristic myelin lipid, sphingomyelin was mainly constituted by very long chain saturated and monounsaturated fatty acids. Among them, nervonic acid (24:1n-9) was the major very long chain fatty acid in Sp, followed by 24:0, 26:1n-9, and 26:0, and its accretion after birth was dramatic. As myelination advanced, 18:1n-9 increased markedly in all four glycerophospholipids, predominating in EP, PS, and PC. In contrast, 22:6n-3 was the most important PUFA in PE in the mature forebrain.
347 citations
TL;DR: Levels of plasmalogen levels in the brains of rats fed a n-3 fatty acid-enriched diet increased, it is plausible, however, that docosahexaenoic acid taken up from the food or formed from linolenic acid was deposited in this phospholipid subclass.
Abstract: Rats were fed either a high linolenic acid (perilla oil) or high eicosapentaenoic + docosahexaenoic acid (fish oil) diet (8%), and the fatty acid and molecular species composition of ethanolamine phosphoglycerides was determined. Gene expression pattern resulting from the feeding of n-3 fatty acids also was studied. Perilla oil feeding, in contrast to fish oil feeding, was not reflected in total fatty acid composition of ethanolamine phosphoglycerides. Levels of the alkenylacyl subclass of ethanolamine phosphoglycerides increased in response to feeding. Similarly, levels of diacyl phosphatidylethanolamine molecular species containing docosahexaenoic acid (18:0/22:6) were higher in perilla-fed or fish oil-fed rat brains whereas those in ethanolamine plasmalogens remained unchanged. Because plasmalogen levels in the brains of rats fed a n-3 fatty acid-enriched diet increased, it is plausible, however, that docosahexaenoic acid taken up from the food or formed from linolenic acid was deposited in this phospholipid subclass. Using cDNA microarrays, 55 genes were found to be overexpressed and 47 were suppressed relative to controls by both dietary regimens. The altered genes included those controlling synaptic plasticity, cytosceleton and membrane association, signal transduction, ion channel formation, energy metabolism, and regulatory proteins. This effect seems to be independent of the chain length of fatty acids, but the n-3 structure appears to be important. Because n-3 polyunsaturated fatty acids have been shown to play an important role in maintaining normal mental functions and docosahexaenoic acid-containing ethanolamine phosphoglyceride (18:0/22:6) molecular species accumulated in response to n-3 fatty acid feeding, a casual relationship between the two events can be surmised.
318 citations
01 Jan 2002
TL;DR: In this article, the action of eight purified phospholipases on intact human erythrocytes has been investigated and it was shown that the unique properties of the enzyme itself, rather than possible contaminations in the purified preparation, are responsible for the observed haemolytic effect.
Abstract: 1 The action of eight purified phospholipases on intact human erythrocytes has been investigated Four enzymes, eg phospholipases A2 from pancreas and Crotalus adamanteus, phospholipase C from Bacillus cereus, and phospholipase D from cabbage produce neither haemolysis nor hydrolysis of phospholipids in intact cells On the other hand, both phospholipases A2 from bee venom and Naja naja cause a non-haemolytic breakdown of more than 50 ~ of the lecithin, while sphingomyelinase C from Staphylococcus aureus is able to produce a non-lytic degradation of more than 80 ~o of the sphingomyelin 2 Phospholipase C from Clostridium welchii appeared to be the only lipolytic enzyme tested, which produces haemolysis of human erythrocytes Evidence is presented that the unique properties of the enzyme itself, rather than possible contaminations in the purified preparation, are responsible for the observed haemolytic effect 3 With non-sealed ghosts, all phospholipases produce essentially complete breakdown of those phospholipids which can be considered as proper substrates for the enzymes involved 4 Due to its absolute requirement for Ca 2 ÷, pancreatic phospholipase A2 can be trapped inside resealed ghosts in the presence of EDTA, without producing phospholipid breakdown during the resealing procedure Subsequent addition of Ca 2 ÷ stimulates phospholipase A z activity at the inside of the resealed cell, eventually leading to lysis Before lysis occurs, however, 25 ~o of the lecithin, half of the phosphatidylethanolamine and some 65 ~ of the phosphatidylserine can be hydrolysed This observation is explained in relation to an asymmetric phospholipid distribution in red cell membranes
318 citations
TL;DR: The finding that SRE BP processing is controlled by different lipids in mammals and flies (sterols and phosphatidylethanolamine, respectively) suggests that an essential function of SREBP is to monitor cell membrane composition and to adjust lipid synthesis accordingly.
Abstract: Animal cells exert exquisite control over the physical and chemical properties of their membranes, but the mechanisms are obscure. We show that phosphatidylethanolamine, the major phospholipid in Drosophila, controls the release of sterol regulatory element-binding protein (SREBP) from Drosophila cell membranes, exerting feedback control on the synthesis of fatty acids and phospholipids. The finding that SREBP processing is controlled by different lipids in mammals and flies (sterols and phosphatidylethanolamine, respectively) suggests that an essential function of SREBP is to monitor cell membrane composition and to adjust lipid synthesis accordingly.
308 citations
TL;DR: Bicarbonate-induced phospholipid scrambling appears to be an important and early physiological event in the capacitation process and was a prerequisite for cholesterol relocation in boar spermatozoa.
Abstract: The capacitating agent bicarbonate/CO(2) has been shown to induce profound changes in the architecture and dynamics within the sperm's plasma membrane lipid bilayer via a cAMP-dependent protein phosphorylation signaling pathway. Here we have investigated the effect of bicarbonate on surface exposure of endogenous aminophospholipids in boar spermatozoa, detecting phosphatidylserine (PS) with fluorescein-conjugated annexin V and phosphatidylethanolamine (PE) with fluorescein-conjugated streptavidin/biotinylated Ro-09-0198. Flow cytometric analyses revealed that incubation with 15 mM bicarbonate induced 30%-70% of live acrosome-intact cells to expose PE very rapidly; this exposure was closely related to a decrease in lipid packing order as detected by enhanced binding of merocyanine 540. PS exposure was detectable in the same proportion of cells, though its expression was slower. Confocal microscopy revealed that exposure of aminophospholipids in intact cells was restricted to the anterior acrosomal region of the head plasma membrane. Aminophospholipid exposure, merocyanine stainability, and a subsequent migration of cholesterol to the apical region of the head plasma membrane, were all under the control of the cAMP-dependent protein phosphorylation pathway. The close coupling of decreased lipid packing order with exposure of PE led us to conclude that bicarbonate was inducing phospholipid scrambling (i.e., collapse of asymmetric transverse distribution), and that the scrambling was a prerequisite for cholesterol relocation. There was no evidence whatever that the bicarbonate-induced scrambling was an apoptotic process. It was not accompanied by major loss of viability or by DNA degeneration or by loss of mitochondrial function, and it could not be blocked by the broad-specificity caspase inhibitors zVAD-fmk and BocD-fmk. In the absence of bicarbonate, scrambling could not be induced by the apoptotic agents UV, staurosporine, or cycloheximide. Bicarbonate-induced phospholipid scrambling thus appears to be an important and early physiological event in the capacitation process.
273 citations
TL;DR: The results suggest that the bulk of LPA produced through platelet activation results from the sequential cleavage of phospholipids to lysophospholIPids by released phospholIPases A1 and A2 and then to LPA by plasma lysphospholipase D.
261 citations
TL;DR: Results are consistent with a model whereby Bax-type proteins change the bending propensity of the membrane to form pores comprised at least in part of lipids in a structure of net positive monolayer curvature.
249 citations
TL;DR: A combination of coimmunofluorescence and subcellular fractionation experiments with various endoplasmic reticulum, Golgi, and nuclear markers confirmed that CPT1 was found in the Golgi and CEPT1 wasFindings allowed for the assignment of specific amino acid residues as structural requirements that directly alter either phospholipid head group or fatty acyl composition.
Abstract: Phosphatidylcholine and phosphatidylethanolamine are the two main phospholipids in eukaryotic cells comprising ~50 and 25% of phospholipid mass, respectively. Phosphatidylcholine is synthesized almost exclusively through the CDP-choline pathway in essentially all mammalian cells. Phosphatidylethanolamine is synthesized through either the CDP-ethanolamine pathway or by the decarboxylation of phosphatidylserine, with the contribution of each pathway being cell type dependent. Two human genes, CEPT1 and CPT1, code for the total compliment of activities that directly synthesize phosphatidylcholine and phosphatidylethanolamine through the CDP-alcohol pathways. CEPT1 transfers a phosphobase from either CDP-choline or CDP-ethanolamine to diacylglycerol to synthesize both phosphatidylcholine and phosphatidylethanolamine, whereas CPT1 synthesizes phosphatidylcholine exclusively. We show through immunofluorescence that brefeldin A treatment relocalizes CPT1, but not CEPT1, implying CPT1 is found in the Golgi. A combination of coimmunofluorescence and subcellular fractionation experiments with various endoplasmic reticulum, Golgi, and nuclear markers confirmed that CPT1 was found in the Golgi and CEPT1 was found in both the endoplasmic reticulum and nuclear membranes. The rate-limiting step for phosphatidylcholine synthesis is catalyzed by the amphitropic CTP:phosphocholine cytidylyltransferase alpha, which is found in the nucleus in most cell types. CTP:phosphocholine cytidylyltransferase alpha is found immediately upstream cholinephosphotransferase, and it translocates from a soluble nuclear location to the nuclear membrane in response to activators of the CDP-choline pathway. Thus, substrate channeling of the CDP-choline produced by CTP:phosphocholine cytidylyltransferase alpha to nuclear located CEPT1 is the mechanism by which upregulation of the CDP-choline pathway increases de novo phosphatidylcholine biosynthesis. In addition, a series of CEPT1 site-directed mutants was generated that allowed for the assignment of specific amino acid residues as structural requirements that directly alter either phospholipid head group or fatty acyl composition. This pinpointed glycine 156 within the catalytic motif as being responsible for the dual CDP-alcohol specificity of CEPT1, whereas mutations within helix 214-228 allowed for the orientation of transmembrane helices surrounding the catalytic site to be definitively positioned.
204 citations
TL;DR: The results suggest that the anti-apoptotic activity of Bcl-XL is not a consequence of its interaction with membranes, but rather with other proteins, such as tBid, which promotes the formation of highly curved non-lamellar phases.
166 citations
TL;DR: HPTLC can be used to study the phospholipid composition of cell-derived microparticles and may also be a useful technique for the analysis of other samples that are available only in minor quantities.
TL;DR: The results indicate that NADPH oxidase-induced oxidative stress in neutrophil-like cells triggers apoptosis and subsequent recognition and removal of these cells through pathways dependent on oxidation and externalization of phosphatidylserine.
TL;DR: Results suggest that the mutation of ros3affects the PE organization on the plasma membrane, rather than PE synthesis or overall organization of the membrane structures, and indicate that Ros3p is a membrane glycoprotein that plays an important role in the phospholipid translocation across the plasma membranes.
TL;DR: This study clearly demonstrates that these ABC transporters of C. albicans are phospholipid translocators and this function could represent one of the physiological functions of such large family of proteins.
Abstract: We have used fluorescent 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD)-tagged phospholipid analogues, NBD-PE (phosphatidylethanolamine), NBD-PC (phosphatidylcholine) and NBD-PS (phosphatidylserine), to demonstrate that Cdr1p and its other homologues, Cdr2p and Cdr3p, belonging to the ATP-binding cassette (ABC) superfamily behave as general phospholipid translocators. Interestingly, CDR1 and CDR2, whose overexpression leads to azole resistance in C. albicans, elicit in-to-out transbilayer phospholipid movement, while CDR3, which is not involved in drug resistance, carries out-to-in translocation of phospholipids between the two monolayers of plasma membrane. Cdr1p, Cdr2p and Cdr3p could be further distinguished on the basis of their sensitivities to different inhibitors. For example, the in-to-out activity associated with Cdr1p and Cdr2p is energy-dependent and sensitive to sulphydryl blocking agents such as N-ethylmaleimide (NEM) and cytoskeleton disrupting agent cytochalasin E, while Cdr3p-associated out-to-in activity is energy-dependent but insensitive to NEM and cytochalasin E. We found that certain drugs, such as fluconazole, cycloheximide and miconazole, to which Cdr1p confers resistance could also affect in-to-out transbilayer movement of NBD-PE, while the same drugs had no effect on Cdr3p-mediated out-to-in translocation of NBD-PE. The ineffectiveness of these drugs to affect Cdr3p mediated out-to-in phospholipid translocation further confirms the inherent difference in the directionality of phospholipid translocation between these pumps. Notwithstanding the role of some of the Cdrps in drug resistance, this study clearly demonstrates that these ABC transporters of C. albicans are phospholipid translocators and this function could represent one of the physiological functions of such large family of proteins.
TL;DR: Results were the same for LacY purified from PE‐containing or PE‐lacking cells, and are consistent with the topology and function of LacY assembled in vivo.
Abstract: In Escherichia coli, the major cytoplasmic domain (C6) of the polytopic membrane protein lactose permease (LacY) is exposed to the opposite side of the membrane from a neighboring periplasmic domain (P7). However, these domains are both exposed on the periplasmic side of the membrane in a mutant of E.coli lacking phosphatidylethanolamine (PE) wherein LacY only mediates facilitated transport. When purified LacY was reconstituted into liposomes lacking PE or phosphatidylcholine (PC), C6 and P7 were on the same side of the bilayer. In liposomes containing PE or PC, C6 and P7 were on opposite sides of the bilayer. Only the presence of PE in the liposomes restored active transport function of LacY as opposed to restoration of only facilitated transport function in the absence of PE. These results were the same for LacY purified from PE-containing or PE-lacking cells, and are consistent with the topology and function of LacY assembled in vivo. Therefore, irrespective of the mechanism of membrane insertion, the subdomain topological orientation and function of LacY are determined primarily by membrane phospholipid composition.
TL;DR: Changes in brain lipid composition and metabolism due to aging involve an increase in acidic phospholipid synthesis and changes in the lipid second messengers diacylglycerol and phosphatidic acid are outlined.
Abstract: In this review, changes in brain lipid composition and metabolism due to aging are outlined. The most striking changes in cerebral cortex and cerebellum lipid composition involve an increase in acidic phospholipid synthesis. The most important changes with respect to fatty acyl composition involve a decreased content in polyunsaturated fatty acids (20:4n-6, 22:4n-6, 22:6n-3) and an increased content in monounsaturated fatty acids (18:1n-9 and 20:1n-9), mainly in ethanolamine and serineglycerophospholipids. Changes in the activity of the enzymes modifying the phospholipid headgroup occur during aging. Serine incorporation into phosphatidylserine through base-exchange reactions and phosphatidylcholine synthesis through phosphatidylethanolamine methylation increases in the aged brain. Phosphatidate phosphohydrolase and phospholipase D activities are also altered in the aged brain thus producing changes in the lipid second messengers diacylglycerol and phosphatidic acid.
TL;DR: Kinetic models showed that the de novo and PEMT pathways are 'channeled' processes; the metabolic pathway information provided by these studies makes the NMR method superior to earlier radioisotope studies.
TL;DR: It is concluded that class B scavenger receptor type I SR-BI is a phagocytosis-inducing PS receptor of Sertoli cells.
TL;DR: The observed decrease of 22:6n-3 species along with PS reduction may represent key biochemical changes underlying losses in brain-hippocampal function associated with n-3 deficiency.
TL;DR: Using in vivo and in vitro phospholipid synthesis/transport measurements, it is demonstrated that the pstA1-1 mutant is defective in PtdSer transport between the MAM and mitochondria, providing compelling evidence that interorganelle Ptd Ser traffic is regulated by ubiquitination.
TL;DR: Salinity can play a significant role in modulating the activities of enzymes acting on lipid metabolism during their natural circannual cycles, according to the results of quantified seasonal effects on fatty acid composition of tissue phospholipids in farmed sea bass.
Abstract: We quantified seasonal effects on fatty acid composition of tissue phospholipids in farmed sea bass. Major changes in percent phosphatidylethanolamine and phosphatidylcholine were observed in all tissues between February and March, and the phosphatidylcholine/phosphatidylethanolamine ratio was drastically reduced at this time. Different changes in the fatty acid composition of total phospholipids were observed in all tissues examined. Fish fed all year on the same commercial diet showed a significant correlation between water salinity and percentage of 22:6n-3 in muscle, liver and gill phospholipids, but no correlation was found between percent 22:6n-3 of phospholipids and water temperature. In each tissue, we observed annual variation in the 20:5n-3/20:4n-6 ratio in phospholipids, but maximum and minimum values occurred at different times in each organ. From these results, we conclude that salinity can play a significant role in modulating the activities of enzymes acting on lipid metabolism during their natural circannual cycles.
TL;DR: It is concluded that Pss2 is responsible for the majority of serine exchange activity in in vitro assays, but a deficiency in this enzyme does not cause perturbations in phospholipid content or severe developmental abnormalities.
TL;DR: The increased transport of C6-NBD-PS in EPG85-257 human gastric carcinoma cells overexpressing MDR1 suggests that MDR 1 Pgp transports endogenous PS, the lipid exhibiting the most pronounced transverse asymmetry in the plasma membrane.
Abstract: The ATP-binding cassette transporter multidrug resistance 1 P-glycoprotein (MDR1 Pgp) has been implicated with the transport of lipids from the inner to the outer leaflet of the plasma membrane. While this has been unambigously shown for the fluorescent lipid analogues [N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]hexanoyl (C6-NBD)-phosphatidylcholine, -phosphatidylethanolamine, -sphingomyelin and -glucosylceramide, by using a novel approach we have now found significantly increased outward transport also for C6-NBD-phosphatidylserine (C6-NBD-PS) in EPG85-257 human gastric carcinoma cells overexpressing MDR1 (coding for MDR1 Pgp). The increased transport of C6-NBD-PS is mediated by MDR1 Pgp, shown by transport reduction nearly to the level of controls in the presence of MDR1 Pgp inhibitors [PSC 833, cyclosporin A and dexniguldipine hydrochloride (Dex)]. Addition of MK 571, a specific inhibitor of the MDR protein MRP1, does not decrease transport in either of the two cell lines. The plasma-membrane association of FITC-annexin V, a fluorescent protein conjugate binding PS, is significantly increased in MDR1-overexpressing cells as compared with controls, and can be reduced by an MDR1 Pgp inhibitor. This suggests that MDR1 Pgp transports endogenous PS, the lipid exhibiting the most pronounced transverse asymmetry in the plasma membrane.
TL;DR: The data indicate that phosphatidylserine forms complexes that accompany mineral formation, while degradation of other membrane phospholipids apparently enables egress of crystalline mineral from the vesicle lumen.
TL;DR: It is demonstrated that the inactivation of complex I from Y. lipolytica by general delipidation could be fully reversed simply by returning the phospholipids that had been removed during the purification procedure and no specific, functionally essential component had been lost.
TL;DR: Exogenous cytidine, probably acting via CTP and the Kennedy cycle, can increase the synthesis and levels of membrane PC and PE in brain cells and is shown to enhance cytidine's effects on any membrane phospholipid.
Abstract: Using rat striatal slices, we examined the effect of cytidine on the conversion of [ 3 H]choline to [ 3 H]phosphatidylcholine ([ 3 H]PC), and on net syntheses of PC, phosphatidylethanolamine (PE), and phosphatidylserine, when media did or did not also contain choline, ethanolamine, or serine. Incubation of striatal slices with cytidine (50-500 μM) caused dose-dependent increases in intracellular cytidine and cytidine triphosphate (CTP) levels and in the rate of incorporation of [ 3 H]choline into membrane [ 3 H] PC. In pulse-chase experiments, cytidine (200 μM) also increased significantly the conversion of [ 3 H]choline to [ 3 H]PC during the chase period. When slices were incubated with this concentration of cytidine for 1 h, small (7%) but significant elevations were obsened in the absolute contents (nmol/mg of protein) of membrane PC and PE (p<0.05), but not phosphatidylserine, the synthesis of which is independent of cytidine-containing CTP. Concurrent exposure to cytidine (200 μM) and choline (10 μM) caused an additional significant increase (p<0.05) in tissue PC levels beyond that produced by cytidine alone. Exposure to choline alone at a higher concentration (40 μM) increased the levels of all three membrane phospholipids (p<0.01); the addition of cytidine, however, did not cause further increases. Concurrent exposure to cytidine (200 μM) and ethanolamine (20 μM) also caused significantly greater elevations (p<0.05) in tissue PE levels than those caused by cytidine alone. In contrast, the addition of serine (500 μM) did not enhance cytidine's effects on any membrane phospholipid. Exposure to serine alone, however, like exposure to sufficient choline, increased levels of all three membrane phospholipids significantly (p<0.01). These data show that exogenous cytidine, probably acting via CTP and the Kennedy cycle, can increase the synthesis and levels of membrane PC and PE in brain cells
TL;DR: The presence of DNA of Chlamydia pneumoniae, herpes simplex virus, and cytomegalovirus was found to be associated with sPLA2(IIA) expression and other signs of local inflammation, appearing to be one important link between the lipid and the inflammation hypothesis of atherosclerosis.
Abstract: Secretory phospholipase A(2) group IIA(sPLA(2) IIA) can be produced and secreted by various cell types either constitutionally or as an acute-phase reactant upon stimulation by proinflammatory cytokines. The enzyme prefers phosphatidylethanolamine and phosphatidylserine as substrates. One important biological function may be the hydrolytic destruction of bacterial membranes. It has been demonstrated, however, that sPLA(2) can also hydrolyse the phospholipid monolayers of high density lipoprotein (HDL) and low density lipoprotein (LDL) in vitro. Secretory phospholipase A(2)-modified LDL show increased affinity to glycosaminoglycans and proteoglycans, a tendency to aggregate, and an enhanced ability to deliver cholesterol to cells. Incubation of cultured macrophages with PLA(2)-treated LDL and HDL is associated with increased intracellular lipid accumulation, resulting in the formation of foam cells. Elevated sPLA(2)(IIA) activity in blood serum leads to an increased clearance of serum cholesterol. Secretory phospholipase A(2)(IIA) can also be detected in the intima, adventitia and media of the atherosclerotic wall not only in developed lesions but also in very early stages of atherosclerosis. The presence of DNA of Chlamydia pneumoniae, herpes simplex virus, and cytomegalovirus was found to be associated with sPLA(2)(IIA) expression and other signs of local inflammation. Thus, sPLA(2)(IIA) appears to be one important link between the lipid and the inflammation hypothesis of atherosclerosis.
TL;DR: The ion channel characteristics such as-no voltage dependence, only one unitary conductance, linear relation ship current-voltage-, are not in favour of the membrane permeabilisation according to the barrel model but rather by the toroidal pore formation.
TL;DR: Kinetic analysis indicates that PIP2 activates PLD by promoting substrate binding to the enzyme, without altering the bulk binding of the enzyme to the micelle surface, and Ca2+ is required for PLDδ activity.
TL;DR: Sphingomyelinase requires the substrate in bilayer form to be in the fluid state, irrespective of whether this is achieved through a thermotropic transition or by modulating bilayer composition, in this way becoming amenable to rapid hydrolysis by the enzyme.