RESUMO
Phosphatidylglycerol (1,2-diacyl-sn-glycero-3-phospho-glycerol) (PG) is one of the most abundant lipids in bacteria. However, the chirality of the carbon atom on glycerol phosphate is different between the three kingdoms, Archaea, Bacteria, and Eukarya. Archaea membranes consist of phospholipids with glycerol-1-phosphate (G1P) in the S configuration, whereas phospholipids of the other two kingdoms contain glycerol-3-phosphate (G3P) having R stereochemistry. In the present study, GC/MS and LC/MS methods sensitively detected G3P and G1P from four bacterial strains (Bacillus amyloliquefaciens, B. subtilis, Clavibacter michiganensis, and Geobacillus stearothermophilus). Strain selection was carried out based on a GenBank search that revealed bacterial sequences associated with both enzymes involved in glycerol-phosphate synthesis, i.e., glycerol-3-phosphate dehydrogenase and glycerol-1-phosphate dehydrogenase. The detection of G1P and G3P was made by comparing the retention times of synthetic standards with those of analyzed samples. The structures of both glycerol phosphates were confirmed by selected ion monitoring (SIM) at m/z 171.006. The total concentration of G3P and G1P was around 30 µM, with a ratio of G3P to G1P of 4:1. We showed that PG was the most abundant phospholipid in all four bacteria by using the following analytical techniques and chromatographic modes: hydrophilic interaction liquid chromatography (HILIC), reversed-phase high-performance liquid chromatography high-resolution electrospray ionization tandem mass spectrometry (RP-HPLC/HR-ESI tandem MS) in negative and positive ionization modes, and an enzymatic cleavage by phospholipase C. By using chiral chromatography, the presence of both enantiomers in the glycerol backbone of some molecular species of PG was revealed. These results allow us to conclude that the bacteria examined here produce both enantiomer glycerol phosphates.
Assuntos
Glicerol , Fosfolipídeos , Bactérias , Cromatografia Líquida , Fosfatos , Fosfatidilgliceróis , Fosfolipídeos/químicaRESUMO
Recent studies have implicated synucleins in several reactions during the biosynthesis of lipids and fatty acids in addition to their recognised role in membrane lipid binding and synaptic functions. These are among aspects of decreased synuclein functions that are still poorly acknowledged especially in regard to pathogenesis in Parkinson's disease. Here, we aimed to add to existing knowledge of synuclein deficiency (i.e., the lack of all three family members), with respect to changes in fatty acids and lipids in plasma, liver, and two brain regions in triple synuclein-knockout (TKO) mice. We describe changes of long-chain polyunsaturated fatty acids (LCPUFA) and palmitic acid in liver and plasma, reduced triacylglycerol (TAG) accumulation in liver and non-esterified fatty acids in plasma of synuclein free mice. In midbrain, we observed counterbalanced changes in the relative concentrations of phosphatidylcholine (PC) and cerebrosides (CER). We also recorded a notable reduction in ethanolamine plasmalogens in the midbrain of synuclein free mice, which is an important finding since the abnormal ether lipid metabolism usually associated with neurological disorders. In summary, our data demonstrates that synuclein deficiency results in alterations of the PUFA synthesis, storage lipid accumulation in the liver, and the reduction of plasmalogens and CER, those polar lipids which are principal compounds of lipid rafts in many tissues. An ablation of all three synuclein family members causes more profound changes in lipid metabolism than changes previously shown to be associated with γ-synuclein deficiency alone. Possible mechanisms by which synuclein deficiency may govern the reported modifications of lipid metabolism in TKO mice are proposed and discussed.
Assuntos
Metabolismo dos Lipídeos , Sinucleínas/genética , Animais , Encéfalo/metabolismo , Ácidos Graxos/metabolismo , Lipídeos/sangue , Fígado/metabolismo , Camundongos , Camundongos KnockoutRESUMO
Despite growing concern about the occurrence of microplastics in aquatic ecosystems there is only rudimentary understanding of the pathways through which any adverse effects might occur. Here, we assess the effects of polystyrene microplastics (PS-MPs; <70 µm) on a common and widespread algal species, Chlorella sorokiniana. We used laboratory exposure to test the hypothesis that the lipids and fatty acids (FAs) are important molecules in the response reactions of algae to this pollutant. Cultivation with PS-MPs systematically reduced the concentration of essential linoleic acid (ALA, C18:3n-3) in C. sorokiniana, concomitantly increasing oleic acid (C18:1n-9). Among the storage triacylglycerols, palmitoleic and oleic acids increased at the expenses of two essential fatty acids, linoleic (LIN, C18:2n-6) and ALA, while PS-MPs had even more pronounced effects on the fatty acid and hydrocarbon composition of waxes and steryl esters. The FA composition of two major chloroplast galactolipids, monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), were affected implying changes in the conformational structure of photosynthetic complexes in ways that can impair the photosynthesis. These data reveal how exposure to polystyrene microplastics can modify the concentrations of lipid molecules that are important intrinsically in cell membranes, and hence the lipid bilayers that could form an important barrier between algal cellular compartments and plastics in the aquatic environment. Changes in lipid synthesis and fatty acid composition in algae could also have repercussions for food quality, growth and stressor resistance in primary consumers. We advocate further studies of microplastics effects on the lipid composition of primary producers, and of their potential propagation through aquatic food webs.
Assuntos
Chlorella , Poliestirenos , Ecossistema , Ácidos Graxos , Ácidos Graxos Essenciais , Água Doce , Microplásticos , PlásticosRESUMO
Lysophosphatidate acyltransferase (LPAAT) catalyses the second step of the Kennedy pathway for triacylglycerol (TAG) synthesis. In this study we expressed Trapaeolum majus LPAAT in Brassica napus (B. napus) cv 12075 to evaluate the effects on lipid synthesis and estimate the flux control coefficient for LPAAT. We estimated the flux control coefficient of LPAAT in a whole plant context by deriving a relationship between it and overall lipid accumulation, given that this process is a exponential. Increasing LPAAT activity resulted in greater TAG accumulation in seeds of between 25% and 29%; altered fatty acid distributions in seed lipids (particularly those of the Kennedy pathway); and a redistribution of label from 14 C-glycerol between phosphoglycerides. Greater LPAAT activity in seeds led to an increase in TAG content despite its low intrinsic flux control coefficient on account of the exponential nature of lipid accumulation that amplifies the effect of the small flux increment achieved by increasing its activity. We have also developed a novel application of metabolic control analysis likely to have broad application as it determines the in planta flux control that a single component has upon accumulation of storage products.
Assuntos
Aciltransferases/metabolismo , Brassica napus/enzimologia , Sementes/química , Triglicerídeos/metabolismo , Aciltransferases/genética , Brassica napus/metabolismo , DNA de Plantas , Regulação Enzimológica da Expressão Gênica/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Plantas Geneticamente Modificadas , Triglicerídeos/química , Tropaeolum/enzimologia , Tropaeolum/genéticaRESUMO
Atherosclerosis and its complications are responsible for one in three global deaths. Nutraceuticals show promise in the prevention and treatment of atherosclerosis but require an indepth understanding of the mechanisms underlying their actions. A previous study showed that the omega-6 fatty acid, dihomo-γ-linolenic acid (DGLA), attenuated atherosclerosis in the apolipoprotein E deficient mouse model system. However, the mechanisms underlying such protective effects of DGLA are poorly understood and were therefore investigated. We show that DGLA attenuates chemokine-driven monocytic migration together with foam cell formation and the expression of key pro-atherogenic genes induced by three pro-inflammatory cytokines in human macrophages. The effect of DGLA on interferon-γ signaling was mediated via inhibition of signal transducer and activator of transcription-1 phosphorylation on serine 727. In relation to anti-foam cell action, DGLA inhibits modified LDL uptake by both macropinocytosis and receptor-mediated endocytosis, the latter by reduction in expression of two key scavenger receptors (SR-A and CD36), and stimulates cholesterol efflux from foam cells. DGLA also improves macrophage mitochondrial bioenergetic profile by decreasing proton leak. Gamma-linolenic acid and prostaglandin E1, upstream precursor and key metabolite respectively of DGLA, also acted in an anti-atherogenic manner. The actions of DGLA extended to other key atherosclerosis-associated cell types with attenuation of endothelial cell proliferation and migration of smooth muscle cells in response to platelet-derived growth factor. This study provides novel insights into the molecular mechanisms underlying the anti-atherogenic actions of DGLA and supports further assessments on its protective effects on plaque regression in vivo and in human trials.
Assuntos
Ácido 8,11,14-Eicosatrienoico/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Animais , Aterosclerose/metabolismo , Aterosclerose/patologia , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Citocinas/metabolismo , Células Espumosas/citologia , Células Espumosas/metabolismo , Humanos , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/metabolismo , Interleucina-1beta/farmacologia , Lipopolissacarídeos/farmacologia , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Monócitos/citologiaRESUMO
With dwindling available agricultural land, concurrent with increased demand for oil, there is much current interest in raising oil crop productivity. We have been addressing this issue by studying the regulation of oil accumulation in oilseed rape (Brassica napus L). As part of this research we have carried out a detailed lipidomic analysis of developing seeds. The molecular species distribution in individual lipid classes revealed quite distinct patterns and showed where metabolic connections were important. As the seeds developed, the molecular species distributions changed, especially in the period of early (20days after flowering, DAF) to mid phase (27DAF) of oil accumulation. The patterns of molecular species of diacylglycerol, phosphatidylcholine and acyl-CoAs were used to predict the possible relative contributions of diacylglycerol acyltransferase (DGAT) and phospholipid:diacylglycerol acyltransferase to triacylglycerol production. Our calculations suggest that DGAT may hold a more important role in influencing the molecular composition of TAG. Enzyme selectivity had an important influence on the final molecular species patterns. Our data contribute significantly to our understanding of lipid accumulation in the world's third most important oil crop.
Assuntos
Brassica napus/metabolismo , Metabolismo dos Lipídeos/fisiologia , Sementes/crescimento & desenvolvimento , Brassica napus/genética , Proteínas de Plantas/biossíntese , Proteínas de Plantas/genética , Sementes/genéticaRESUMO
Despite being unable to activate the cognate ghrelin receptor (GHS-R), unacylated ghrelin (UAG) possesses a unique activity spectrum that includes promoting bone marrow adipogenesis. Since a receptor mediating this action has not been identified, we re-appraised the potential interaction of UAG with GHS-R in the regulation of bone marrow adiposity. Surprisingly, the adipogenic effects of intra-bone marrow (ibm)-infused acylated ghrelin (AG) and UAG were abolished in male GHS-R-null mice. Gas chromatography showed that isolated tibial marrow adipocytes contain the medium-chain fatty acids utilised in the acylation of UAG, including octanoic acid. Additionally, immunohistochemistry and immunogold electron microscopy revealed that tibial marrow adipocytes show prominent expression of the UAG-activating enzyme ghrelin O-acyl transferase (GOAT), which is located in the membranes of lipid trafficking vesicles and in the plasma membrane. Finally, the adipogenic effect of ibm-infused UAG was completely abolished in GOAT-KO mice. Thus, the adipogenic action of exogenous UAG in tibial marrow is dependent upon acylation by GOAT and activation of GHS-R. This suggests that UAG is subject to target cell-mediated activation - a novel mechanism for manipulating hormone activity.
Assuntos
Aciltransferases/metabolismo , Adipogenia , Medula Óssea/metabolismo , Grelina/metabolismo , Proteínas de Membrana/metabolismo , Receptores de Grelina/metabolismo , Acilação , Animais , Cromatografia Gasosa , Imuno-Histoquímica , Camundongos , Camundongos Knockout , Microscopia Imunoeletrônica , Receptores de Grelina/deficiênciaRESUMO
The regulation of lipid synthesis in oil seeds is still not fully understood. Oilseed rape (Brassica napus) is the third most productive vegetable oil crop on the global market; therefore, increasing our understanding of lipid accumulation in oilseed rape seeds is of great economic, as well as intellectual, importance. Matrix-assisted laser/desorption ionization-mass spectrometry imaging (MALDI-MSI) is a technique that allows the mapping of metabolites directly onto intact biological tissues, giving a spatial context to metabolism. We have used MALDI-MSI to study the spatial distribution of two major lipid species, triacylglycerols and phosphatidylcholines. A dramatic, heterogenous landscape of molecular species was revealed, demonstrating significantly different lipid compositions between the various tissue types within the seed. The embryonic axis was found to be particularly enriched in palmitic acid, while the seed coat/aleurone layer accumulated vaccenic, linoleic, and α-linoleic acids. Furthermore, the lipid composition of the inner and outer cotyledons differed from each other, a remarkable discovery given the supposed identical functionality of these two tissues. Triacylglycerol and phosphatidylcholine molecular species distribution was analyzed through a developmental time series covering early seed lipid accumulation to seed maturity. The spatial patterning of lipid molecular species did not vary significantly during seed development. Data gathered using MALDI-MSI was verified through gas chromatography analysis of dissected seeds. The distinct lipid distribution profiles observed imply differential regulation of lipid metabolism between the different tissue types of the seed. Further understanding of this differential regulation will enhance efforts to improve oilseed rape productivity and quality.
Assuntos
Brassica napus/metabolismo , Lipídeos/biossíntese , Óleos de Plantas/metabolismo , Sementes/metabolismo , Análise Espaço-Temporal , Cromatografia Gasosa , Cotilédone/metabolismo , Ácido Linoleico/análise , Lipídeos/química , Espectroscopia de Ressonância Magnética , Ácidos Oleicos/análise , Ácido Palmítico/análise , Fosfatidilcolinas/biossíntese , Fosfatidilcolinas/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Fatores de Tempo , Triglicerídeos/biossíntese , Triglicerídeos/químicaRESUMO
Prader-Willi syndrome (PWS), a neurodevelopmental disorder caused by loss of paternal gene expression from 15q11-q13, is characterised by growth retardation, hyperphagia and obesity. However, as single gene mutation mouse models for this condition display an incomplete spectrum of the PWS phenotype, we have characterised the metabolic impairment in a mouse model for 'full' PWS, in which deletion of the imprinting centre (IC) abolishes paternal gene expression from the entire PWS cluster. We show that PWS-ICdel mice displayed postnatal growth retardation, with reduced body weight, hyperghrelinaemia and marked abdominal leanness; proportionate retroperitoneal, epididymal/omental and inguinal white adipose tissue (WAT) weights being reduced by 82%, 84% and 67%, respectively. PWS-ICdel mice also displayed a 48% reduction in proportionate interscapular brown adipose tissue (isBAT) weight with significant 'beiging' of abdominal WAT, and a 2°C increase in interscapular surface body temperature. Maintenance of PWS-ICdel mice under thermoneutral conditions (30°C) suppressed the thermogenic activity in PWS-ICdel males, but failed to elevate the abdominal WAT weight, possibly due to a normalisation of caloric intake. Interestingly, PWS-ICdel mice also showed exaggerated food hoarding behaviour with standard and high-fat diets, but despite becoming hyperphagic when switched to a high-fat diet, PWS-ICdel mice failed to gain weight. This evidence indicates that, unlike humans with PWS, loss of paternal gene expression from the PWS cluster in mice results in abdominal leanness. Although reduced subcutaneous insulation may lead to exaggerated heat loss and thermogenesis, abdominal leanness is likely to arise from a reduced lipid storage capacity rather than increased energy utilisation in BAT.
Assuntos
Tecido Adiposo Branco/metabolismo , Peso Corporal/fisiologia , Mutação , Fenótipo , Síndrome de Prader-Willi/genética , Magreza/genética , Tecido Adiposo Marrom/metabolismo , Animais , Metilação de DNA , Modelos Animais de Doenças , Masculino , Camundongos , Deleção de Sequência , Termogênese/fisiologiaRESUMO
Alzheimer's disease (AD) is of major concern in ageing populations and we have used the Tg2576 mouse model to understand connections between brain lipids and amyloid pathology. Because dietary docosahexaenoic acid (DHA) has been identified as beneficial, we compared mice fed with a DHA-supplemented diet to those on a nutritionally-sufficient diet. Major phospholipids from cortex, hippocampus and cerebellum were separated and analysed. Each phosphoglyceride had a characteristic fatty acid composition which was similar in cortex and hippocampus but different in the cerebellum. The biggest changes on DHA-supplementation were within ethanolamine phospholipids which, together with phosphatidylserine, had the highest proportions of DHA. Reciprocal alterations in DHA and arachidonate were found. The main diet-induced alterations were found in ethanolamine phospholipids, (and included their ether derivatives), as were the changes observed due to genotype. Tg mice appeared more sensitive to diet with generally lower DHA percentages when on the standard diet and higher relative proportions of DHA when the diet was supplemented. All four major phosphoglycerides analysed showed age-dependent decreases in polyunsaturated fatty acid contents. These data provide, for the first time, a detailed evaluation of phospholipids in different brain areas previously shown to be relevant to behaviour in the Tg2576 mouse model for AD. The lipid changes observed with genotype are consistent with the subtle alterations found in AD patients, especially for the ethanolamine phospholipid molecular species. They also emphasise the contrasting changes in fatty acid content induced by DHA supplementation within individual phospholipid classes.
Assuntos
Doença de Alzheimer/metabolismo , Encéfalo/metabolismo , Suplementos Nutricionais , Ácidos Docosa-Hexaenoicos/administração & dosagem , Fosfolipídeos/metabolismo , Doença de Alzheimer/genética , Animais , Cerebelo/metabolismo , Córtex Cerebral/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Modelos Animais de Doenças , Ácidos Docosa-Hexaenoicos/farmacologia , Ácidos Graxos/metabolismo , Glicerofosfolipídeos/metabolismo , Hipocampo/metabolismo , Humanos , Metabolismo dos Lipídeos/efeitos dos fármacos , Camundongos Transgênicos , Fosfatidiletanolaminas/metabolismo , Fosfatidilserinas/metabolismo , Espectrometria de Massas em Tandem/métodosRESUMO
We tested the influence of two light intensities [40 and 300 µmol PAR / (m(2)s)] on the fatty acid composition of three distinct lipid classes in four freshwater phytoplankton species. We chose species of different taxonomic classes in order to detect potentially similar reaction characteristics that might also be present in natural phytoplankton communities. From samples of the bacillariophyte Asterionella formosa, the chrysophyte Chromulina sp., the cryptophyte Cryptomonas ovata and the zygnematophyte Cosmarium botrytis we first separated glycolipids (monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol), phospholipids (phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, and phosphatidylserine) as well as non-polar lipids (triacylglycerols), before analyzing the fatty acid composition of each lipid class. High variation in the fatty acid composition existed among different species. Individual fatty acid compositions differed in their reaction to changing light intensities in the four species. Although no generalizations could be made for species across taxonomic classes, individual species showed clear but small responses in their ecologically-relevant omega-3 and omega-6 polyunsaturated fatty acids (PUFA) in terms of proportions and of per tissue carbon quotas. Knowledge on how lipids like fatty acids change with environmental or culture conditions is of great interest in ecological food web studies, aquaculture, and biotechnology, since algal lipids are the most important sources of omega-3 long-chain PUFA for aquatic and terrestrial consumers, including humans.
RESUMO
Extracellular vesicles (EVs) are submicron vesicles released from many cell types, including adipocytes. EVs are implicated in the pathogenesis of obesity-driven cardiovascular disease, although the characteristics of adipocyte-derived EVs are not well described. We sought to define the characteristics of adipocyte-derived EVs before and after adipogenesis, hypothesising that adipogenesis would affect EV structure, molecular composition and function. Using 3T3-L1 cells, EVs were harvested at day 0 and day 15 of differentiation. EV and cell preparations were visualised by electron microscopy and EVs quantified by nanoparticle tracking analysis (NTA). EVs were then assessed for annexin V positivity using flow cytometry; lipid and phospholipid composition using 2D thin layer chromatography and gas chromatography; and vesicular protein content by an immuno-phenotyping assay. Pre-adipogenic cells are connected via a network of protrusions and EVs at both time points display classic EV morphology. EV concentration is elevated prior to adipogenesis, particularly in exosomes and small microvesicles. Parent cells contain higher proportions of phosphatidylserine (PS) and show higher annexin V binding. Both cells and EVs contain an increased proportion of arachidonic acid at day 0. PREF-1 was increased at day 0 whilst adiponectin was higher at day 15 indicating EV protein content reflects the stage of adipogenesis of the cell. Our data suggest that EV production is higher in cells before adipogenesis, particularly in vesicles <300 nm. Cells at this time point possess a greater proportion of PS (required for EV generation) whilst corresponding EVs are enriched in signalling fatty acids, such as arachidonic acid, and markers of adipogenesis, such as PREF-1 and PPARγ.
RESUMO
Lipoprotein-apheresis (apheresis) removes LDL-cholesterol in patients with severe dyslipidemia. However, reduction is transient, indicating that the long-term cardiovascular benefits of apheresis may not solely be due to LDL removal. Microparticles (MPs) are submicron vesicles released from the plasma membrane of cells. MPs, particularly platelet-derived MPs, are increasingly being linked to the pathogenesis of many diseases. We aimed to characterize the effect of apheresis on MP size, concentration, cellular origin, and fatty acid concentration in individuals with familial hypercholesterolemia (FH). Plasma and MP samples were collected from 12 individuals with FH undergoing routine apheresis. Tunable resistive pulse sensing (np200) and nanoparticle tracking analysis measured a fall in MP concentration (33 and 15%, respectively; P < 0.05) pre- to post-apheresis. Flow cytometry showed MPs were predominantly annexin V positive and of platelet (CD41) origin both pre- (88.9%) and post-apheresis (88.4%). Fatty acid composition of MPs differed from that of plasma, though apheresis affected a similar profile of fatty acids in both compartments, as measured by GC-flame ionization detection. MP concentration was also shown to positively correlate with thrombin generation potential. In conclusion, we show apheresis nonselectively removes annexin V-positive platelet-derived MPs in individuals with FH. These MPs are potent inducers of coagulation and are elevated in CVD; this reduction in pathological MPs could relate to the long-term benefits of apheresis.
Assuntos
Remoção de Componentes Sanguíneos , Micropartículas Derivadas de Células/metabolismo , LDL-Colesterol/sangue , Hiperlipoproteinemia Tipo II/sangue , Hiperlipoproteinemia Tipo II/terapia , Idoso , Feminino , Citometria de Fluxo , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Although there is much knowledge of the enzymology (and genes coding the proteins) of lipid biosynthesis in higher plants, relatively little attention has been paid to regulation. We have demonstrated the important role for cholinephosphate cytidylyltransferase in the biosynthesis of the major extra-plastidic membrane lipid, phosphatidylcholine. We followed this work by applying control analysis to light-induced fatty acid synthesis. This was the first such application to lipid synthesis in any organism. The data showed that acetyl-CoA carboxylase was very important, exerting about half of the total control. We then applied metabolic control analysis to lipid accumulation in important oil crops - oilpalm, olive, and rapeseed. Recent data with soybean show that the block of fatty acid biosynthesis reactions exerts somewhat more control (63%) than lipid assembly although both are clearly very important. These results suggest that gene stacks, targeting both parts of the overall lipid synthesis pathway will be needed to increase significantly oil yields in soybean. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.
Assuntos
Regulação da Expressão Gênica de Plantas , Glycine max/metabolismo , Metabolismo dos Lipídeos , Lipídeos/biossínteseRESUMO
Oil crops are in increasing demand both for food and as renewable sources of chemicals. It is therefore vital to understand how oil accumulation is regulated. Different ways of obtaining such information are discussed with an emphasis on metabolic control analysis. The usefulness of the latter has been well-illustrated by its application to help raise yields in oilseed rape.
Assuntos
Produtos Agrícolas/metabolismo , Lipídeos/biossíntese , Óleos de Plantas/metabolismo , Cruzamento , Produtos Agrícolas/genética , Melhoramento Genético , Redes e Vias Metabólicas/genéticaRESUMO
Synucleins are a family of homologous proteins principally known for their involvement in neurodegeneration. γ-Synuclein is highly expressed in human white adipose tissue and increased in obesity. Here we show that γ-synuclein is nutritionally regulated in white adipose tissue whereas its loss partially protects mice from high-fat diet (HFD)-induced obesity and ameliorates some of the associated metabolic complications. Compared with HFD-fed WT mice, HFD-fed γ-synuclein-null mutant mice display increased lipolysis, lipid oxidation, and energy expenditure, and reduced adipocyte hypertrophy. Knockdown of γ-synuclein in adipocytes causes redistribution of the key lipolytic enzyme ATGL to lipid droplets and increases lipolysis. γ-Synuclein-deficient adipocytes also contain fewer SNARE complexes of a type involved in lipid droplet fusion. We hypothesize that γ-synuclein may deliver SNAP-23 to the SNARE complexes under lipogenic conditions. Via these independent but complementary roles, γ-synuclein may coordinately modulate lipid storage by influencing lipolysis and lipid droplet formation. Our data reveal γ-synuclein as a regulator of lipid handling in adipocytes, the function of which is particularly important in conditions of nutrient excess.
Assuntos
Tecido Adiposo/metabolismo , Lipólise , Obesidade/metabolismo , Células 3T3 , Adipócitos/citologia , Animais , Dieta , Genótipo , Lipídeos/química , Lipogênese , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Modelos Biológicos , gama-SinucleínaRESUMO
The interrelationship between brown adipose tissue (BAT) and white adipose tissue (WAT) is emerging as an important factor in obesity, but the effect of impairing non-shivering thermogenesis in BAT on lipid storage in WAT remains unclear. To address this, we have characterized the metabolic phenotype of a mouse model for Costeff syndrome, in which a point mutation in the mitochondrial membrane protein Opa3 impairs mitochondrial activity. Opa3(L122P) mice displayed an 80% reduction in insulin-like growth factor 1, postnatal growth retardation and hepatic steatosis. A 90% reduction in uncoupling protein 1 (UCP1) expression in interscapular BAT was accompanied by a marked reduction in surface body temperature, with a 2.5-fold elevation in interscapular BAT mass and lipid storage. The sequestration of circulating lipid into BAT resulted in profound reductions in epididymal and retroperitoneal WAT mass, without affecting subcutaneous WAT. The histological appearance and intense mitochondrial staining in intra-abdominal WAT suggest significant 'browning', but with UCP1 expression in WAT of Opa3(L122P) mice only 62% of that in wild-type littermates, any precursor differentiation does not appear to result in thermogenically active beige adipocytes. Thus, we have identified Opa3 as a novel regulator of lipid metabolism, coupling lipid uptake with lipid processing in liver and with thermogenesis in BAT. These findings indicate that skeletal and metabolic impairment in Costeff syndrome may be more significant than previously thought and that uncoupling lipid uptake from lipid metabolism in BAT may represent a novel approach to controlling WAT mass in obesity.
Assuntos
Gordura Abdominal/metabolismo , Adiposidade/genética , Síndrome de Costello/genética , Síndrome de Costello/metabolismo , Mitocôndrias/metabolismo , Proteínas/genética , Termogênese/genética , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Marrom/patologia , Animais , Síndrome de Costello/sangue , Modelos Animais de Doenças , Feminino , Genótipo , Metabolismo dos Lipídeos , Fígado/metabolismo , Fígado/patologia , Masculino , Camundongos , Camundongos Knockout , Fenótipo , Proteínas/metabolismoRESUMO
Metabolic control analysis allows the study of metabolic regulation. We applied both single- and double-manipulation top-down control analysis to examine the control of lipid accumulation in developing oilseed rape (Brassica napus) embryos. The biosynthetic pathway was conceptually divided into two blocks of reactions (fatty acid biosynthesis (Block A), lipid assembly (Block B)) connected by a single system intermediate, the acyl-coenzyme A (acyl-CoA) pool. Single manipulation used exogenous oleate. Triclosan was used to inhibit specifically Block A, whereas diazepam selectively manipulated flux through Block B. Exogenous oleate inhibited the radiolabelling of fatty acids from [1-(14)C]acetate, but stimulated that from [U-14C]glycerol into acyl lipids. The calculation of group flux control coefficients showed that c. 70% of the metabolic control was in the lipid assembly block of reactions. Monte Carlo simulations gave an estimation of the error of the resulting group flux control coefficients as 0.27±0.06 for Block A and 0.73±0.06 for Block B. The two methods of control analysis gave very similar results and showed that Block B reactions were more important under our conditions. This contrasts notably with data from oil palm or olive fruit cultures and is important for efforts to increase oilseed rape lipid yields.
Assuntos
Brassica napus/embriologia , Brassica napus/metabolismo , Lipídeos/biossíntese , Metabolômica/métodos , Óleos de Plantas/metabolismo , Sementes/metabolismo , Acil Coenzima A/metabolismo , Brassica napus/efeitos dos fármacos , Radioisótopos de Carbono , Diazepam/farmacologia , Ácidos Graxos Monoinsaturados , Lipídeos/classificação , Ácido Oleico/farmacologia , Óleo de Brassica napus , Sementes/efeitos dos fármacos , Fatores de Tempo , Triclosan/farmacologiaRESUMO
Lipid droplet formation and subsequent steatosis (the abnormal retention of lipids within a cell) has been reported to contribute to hepatotoxicity and is an adverse effect of many pharmacological agents including the antiepileptic drug valproic acid (VPA). In this study, we have developed a simple model system (Dictyostelium discoideum) to investigate the effects of VPA and related compounds in lipid droplet formation. In mammalian hepatocytes, VPA increases lipid droplet accumulation over a 24-hour period, giving rise to liver cell damage, and we show a similar effect in Dictyostelium following 30 minutes of VPA treatment. Using (3)H-labelled polyunsaturated (arachidonic) or saturated (palmitic) fatty acids, we shown that VPA treatment of Dictyostelium gives rise to an increased accumulation of both types of fatty acids in phosphatidylcholine, phosphatidylethanolamine and non-polar lipids in this time period, with a similar trend observed in human hepatocytes (Huh7 cells) labelled with [(3)H]arachidonic acid. In addition, pharmacological inhibition of ß-oxidation in Dictyostelium phenocopies fatty acid accumulation, in agreement with data reported in mammalian systems. Using Dictyostelium, we then screened a range of VPA-related compounds to identify those with high and low lipid-accumulation potential, and validated these activities for effects on lipid droplet formation by using human hepatocytes. Structure-activity relationships for these VPA-related compounds suggest that lipid accumulation is independent of VPA-catalysed teratogenicity and inositol depletion. These results suggest that Dictyostelium could provide both a novel model system for the analysis of lipid droplet formation in human hepatocytes and a rapid method for identifying VPA-related compounds that show liver toxicology.
Assuntos
Dictyostelium/efeitos dos fármacos , Dictyostelium/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Ácido Valproico/toxicidade , Linhagem Celular , Ácidos Graxos/metabolismo , Fígado Gorduroso/etiologia , Fígado Gorduroso/metabolismo , Humanos , Inositol/metabolismo , Cinética , Modelos Biológicos , Especificidade da Espécie , Teratogênicos/toxicidade , Ácido Valproico/análogos & derivados , Ácido Valproico/químicaRESUMO
Atherosclerosis, the leading cause of death in the Western world, is driven by chronic inflammation within the artery wall. Elements of the complement cascade are implicated in the pathogenesis, because complement proteins and their activation products are found in the atherosclerotic plaque. We examined the role of CD55, a membrane inhibitor of the complement component 3 (C3) convertase, which converts C3 into C3a and C3b, in atherosclerosis. CD55-deficient (CD55(-/-)) mice were crossed onto the atherosclerosis-prone apolipoprotein E (apoE)-deficient (apoE(-/-)) background. High fat-fed male apoE(-/-)/CD55(-/-) mice were strongly protected from developing atherosclerosis compared with apoE(-/-) controls. Lipid profiling showed significantly lower levels of triglycerides, nonesterified fatty acids, and cholesterol in apoE(-/-)/CD55(-/-) mice than that in controls after high-fat feeding, whereas body fat in apoE(-/-)/CD55(-/-) mice content was increased. Plasma levels of C3 fell, whereas concentrations of C3adesArg (alias acylation stimulating protein; ASP), produced by serum carboxypeptidase N-mediated desargination of C3a, increased in nonfasted high fat-fed apoE(-/-)/CD55(-/-) mice, indicating complement activation. Thus, complement dysregulation in the absence of CD55 provoked increased C3adesArg production that, in turn, caused altered lipid handling, resulting in atheroprotection and increased adiposity. Interventions that target complement activation in adipose tissue should be explored as lipid-decreasing strategies.