Changes In Phospholipid Composition Research Articles

Inhibiting fatty acid synthesis overcomes colistin resistance.

Treating multidrug-resistant infections has increasingly relied on last-resort antibiotics, including polymyxins, for example colistin. As polymyxins are given routinely, the prevalence of their resistance is on the rise and increases mortality rates of sepsis patients. The global dissemination of plasmid-borne colistin resistance, driven by the emergence of mcr-1, threatens to diminish the therapeutic utility of polymyxins from an already shrinking antibiotic arsenal. Restoring sensitivity to polymyxins using combination therapy with sensitizing drugs is a promising approach to reviving its clinical utility. Here we describe the ability of the biotin biosynthesis inhibitor, MAC13772, to synergize with colistin exclusively against colistin-resistant bacteria. MAC13772 indirectly disrupts fatty acid synthesis (FAS) and restores sensitivity to the last-resort antibiotic, colistin. Accordingly, we found that combinations of colistin and other FAS inhibitors, cerulenin, triclosan and Debio1452-NH3, had broad potential against both chromosomal and plasmid-mediated colistin resistance in chequerboard and lysis assays. Furthermore, combination therapy with colistin and the clinically relevant FabI inhibitor, Debio1452-NH3, showed efficacy against mcr-1 positive Klebsiella pneumoniae and colistin-resistant Escherichia coli systemic infections in mice. Using chemical genomics, lipidomics and transcriptomics, we explored the mechanism of the interaction. We propose that inhibiting FAS restores colistin sensitivity by depleting lipid synthesis, leading to changes in phospholipid composition. In all, this work reveals a surprising link between FAS and colistin resistance.

Elevated Adipocyte Membrane Phospholipid Saturation Does Not Compromise Insulin Signaling.

Increased saturated fatty acid (SFA) levels in membrane phospholipids have been implicated in the development of metabolic disease. Here, we tested the hypothesis that increased SFA content in cell membranes negatively impacts adipocyte insulin signaling. Preadipocyte cell models with elevated SFA levels in phospholipids were generated by disrupting the ADIPOR2 locus, which resulted in a striking twofold increase in SFA-containing phosphatidylcholines and phosphatidylethanolamines, which persisted in differentiated adipocytes. Similar changes in phospholipid composition were observed in white adipose tissues isolated from the ADIPOR2-knockout mice. The SFA levels in phospholipids could be further increased by treating ADIPOR2-deficient cells with palmitic acid and resulted in reduced membrane fluidity and endoplasmic reticulum stress in mouse and human preadipocytes. Strikingly, increased SFA levels in differentiated adipocyte phospholipids had no effect on adipocyte gene expression or insulin signaling invitro. Similarly, increased adipocyte phospholipid saturation did not impair white adipose tissue function invivo, even in mice fed a high-saturated fat diet at thermoneutrality. We conclude that increasing SFA levels in adipocyte phospholipids is well tolerated and does not affect adipocyte insulin signaling invitro and invivo.

Transient Complexity of E. coli Lipidome Is Explained by Fatty Acyl Synthesis and Cyclopropanation.

In the case of many bacteria, such as Escherichia coli, the composition of lipid molecules, termed the lipidome, temporally adapts to different environmental conditions and thus modifies membrane properties to permit growth and survival. Details of the relationship between the environment and lipidome composition are lacking, particularly for growing cultures under either favourable or under stress conditions. Here, we highlight compositional lipidome changes by describing the dynamics of molecular species throughout culture-growth phases. We show a steady cyclopropanation of fatty acyl chains, which acts as a driver for lipid diversity. There is a bias for the cyclopropanation of shorter fatty acyl chains (FA 16:1) over longer ones (FA 18:1), which likely reflects a thermodynamic phenomenon. Additionally, we observe a nearly two-fold increase in saturated fatty acyl chains in response to the presence of ampicillin and chloramphenicol, with consequences for membrane fluidity and elasticity, and ultimately bacterial stress tolerance. Our study provides the detailed quantitative lipidome composition of three E. coli strains across culture-growth phases and at the level of the fatty acyl chains and provides a general reference for phospholipid composition changes in response to perturbations. Thus, lipidome diversity is largely transient and the consequence of lipid synthesis and cyclopropanation.

Changes in Phospholipid Composition of the Human Cerebellum and Motor Cortex during Normal Ageing.

(1) Background: Changes in phospholipid (phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine, i.e., PC, PE and PS) composition with age in the mitochondrial and microsomal membranes of the human cerebellum and motor cortex were examined and compared to previous analyses of the prefrontal cortex, hippocampus and entorhinal cortex. (2) Methods: Nano-electrospray ionization on a hybrid triple quadrupole–linear ion trap mass spectrometer was used to analyse the brain regions of subjects aged 18–104 years. (3) Results: With age, the cerebellum showed many changes in the major phospholipids (>10% of the phospholipid class). In both membrane types, these included increases in PE 18:0_22:6 and PS 18:0_22:6, decreases in PE 18:0_20:4 and PS 18:0_18:1 and an increase in PC 16:0_16:0 (microsomal membrane only). In addition, twenty-one minor phospholipids also changed. In the motor cortex, only ten minor phospholipids changed with age. With age, the acyl composition of the membranes in the cerebellum increased in docosahexaenoic acid (22:6) and decreased in the arachidonic (20:4) and adrenic (22:4) acids. A comparison of phospholipid changes in the cerebellum, motor cortex and other brain areas is provided. (4) Conclusions: The cerebellum is exceptional in the large number of major phospholipids that undergo changes (with consequential changes in acyl composition) with age, whereas the motor cortex is highly resistant to change.

Lack of VMP1 impairs hepatic lipoprotein secretion and promotes non-alcoholic steatohepatitis.

Background & Aims:Vacuole membrane protein 1 (VMP1) is an endoplasmic reticulum (ER) transmembrane protein that regulates the formation of autophagosomes and lipid droplets. Recent evidence suggests that VMP1 plays a critical role in lipoprotein secretion in zebra fish and cultured cells. However, the pathophysiological roles and mechanisms by which VMP1 regulates lipoprotein secretion and lipid accumulation in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are unknown.Methods:Liver-specific and hepatocyte-specific Vmp1 knockout mice as well as Vmp1 knock-in mice were generated by crossing Vmp1flox or Vmp1KI mice with albumin-Cre mice or by injecting AAV8-TBG-cre, respectively. Lipid and energy metabolism in these mice were characterized by metabolomic and transcriptome analyses. Mice with hepatic overexpression of VMP1 who were fed a NASH diet were also characterized.Results:Hepatocyte-specific deletion of Vmp1 severely impaired VLDL secretion resulting in massive hepatic steatosis, hepatocyte death, inflammation and fibrosis, which are hallmarks of NASH. Mechanistically, loss of Vmp1 led to decreased hepatic levels of phosphatidylcholine and phosphatidylethanolamine as well as to changes in phospholipid composition. Deletion of Vmp1 in mouse liver also led to the accumulation of neutral lipids in the ER bilayer and impaired mitochondrial beta-oxidation. Overexpression of VMP1 ameliorated steatosis in diet-induced NASH by improving VLDL secretion. Importantly, we also showed that decreased liver VMP1 is associated with NAFLD/NASH in humans.Conclusions:Our results provide novel insights on the role of VMP1 in regulating hepatic phospholipid synthesis and lipoprotein secretion in the pathogenesis of NAFLD/NASH.Lay summary:Non-alcoholic fatty liver disease and its more severe form, non-alcoholic steatohepatitis, are associated with a build-up of fat in the liver (steatosis). However, the exact mechanisms that underly steatosis in patients are not completely understood. Herein, the authors identified that the lack of a protein called VMP1 impairs the secretion and metabolism of fats in the liver and could therefore contribute to the development and progression of non-alcoholic fatty liver disease.

Mitochondrial Dynamics in SARS-COV2 Spike Protein Treated Human Microglia: Implications for Neuro-COVID.

Emerging clinical data from the current COVID-19 pandemic suggests that ~ 40% of COVID-19 patients develop neurological symptoms attributed to viral encephalitis while in COVID long haulers chronic neuro-inflammation and neuronal damage result in a syndrome described as Neuro-COVID. We hypothesize that SAR-COV2 induces mitochondrial dysfunction and activation of the mitochondrial-dependent intrinsic apoptotic pathway, resulting in microglial and neuronal apoptosis. The goal of our study was to determine the effect of SARS-COV2 on mitochondrial biogenesis and to monitor cell apoptosis in human microglia non-invasively in real time using Raman spectroscopy, providing a unique spatio-temporal information on mitochondrial function in live cells. We treated human microglia with SARS-COV2 spike protein and examined the levels of cytokines and reactive oxygen species (ROS) production, determined the effect of SARS-COV2 on mitochondrial biogenesis and examined the changes in molecular composition of phospholipids. Our results show that SARS- COV2 spike protein increases the levels of pro-inflammatory cytokines and ROS production, increases apoptosis and increases the oxygen consumption rate (OCR) in microglial cells. Increases in OCR are indicative of increased ROS production and oxidative stress suggesting that SARS-COV2 induced cell death. Raman spectroscopy yielded significant differences in phospholipids such as Phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylcholine (PC), which account for ~ 80% of mitochondrial membrane lipids between SARS-COV2 treated and untreated microglial cells. These data provide important mechanistic insights into SARS-COV2 induced mitochondrial dysfunction which underlies neuropathology associated with Neuro-COVID.Graphical

A comparative study on the lipidome of normal knee synovial fluid from humans and horses.

The current limitations in evaluating synovial fluid (SF) components in health and disease and between species are due in part to the lack of data on normal SF, because of low availability of SF from healthy articular joints. Our study aimed to quantify species-dependent differences in phospholipid (PL) profiles of normal knee SF obtained from equine and human donors. Knee SF was obtained during autopsy by arthrocentesis from 15 and 13 joint-healthy human and equine donors, respectively. PL species extracted from SF were quantitated by mass spectrometry whereas ELISA determined apolipoprotein (Apo) B-100. Wilcoxon’s rank sum test with adjustment of scores for tied values was applied followed by Holm´s method to account for multiple testing. Six lipid classes with 89 PL species were quantified, namely phosphatidylcholine, lysophosphatidylcholine, sphingomyelin, phosphatidylethanolamine, plasmalogen, and ceramide. Importantly, equine SF contains about half of the PL content determined in human SF with some characteristic changes in PL composition. Nutritional habits, decreased apolipoprotein levels and altered enzymatic activities may have caused the observed different PL profiles. Our study provides comprehensive quantitative data on PL species levels in normal human and equine knee SF so that research in joint diseases and articular lubrication can be facilitated.

Targeted assessment of the metabolome in skeletal muscle and in serum of dairy cows supplemented with conjugated linoleic acid during early lactation

In the dairy cow, late gestation and early lactation are characterized by a complexity of metabolic processes required for the homeorhetic adaptation to the needs of fetal growth and milk production. Skeletal muscle plays an important role in this adaptation. The objective of this study was to characterize the metabolome in skeletal muscle (semitendinosus muscle) and in serum of dairy cows in the context of the physiological changes occurring in early lactation and to test the effects of dietary supplementation (from d 1 in milk onwards) with conjugated linoleic acids (sCLA; 100 g/d; supplying 7.6 g of cis-9,trans-11 CLA and 7.6 g of trans-10,cis-12 CLA per cow/d; n = 11) compared with control fat-supplemented cows (CTR; n = 10). The metabolome was characterized in skeletal muscle samples collected on d 21 and 70 after calving in conjunction with their serum counterpart using a targeted metabolomics approach (AbsoluteIDQ p180 kit; Biocrates Life Sciences AG, Innsbruck, Austria). Thereby 188 metabolites from 6 different compound classes (acylcarnitines, amino acids, biogenic amines, glycerophospholipids, sphingolipids, and hexoses) were quantified in both sample types. In both groups, dry matter intake increased after calving. It was lower in sCLA than in CTR on d 21, which resulted in reduced calculated net energy and metabolizable protein balances. On d 21, the concentrations of dopamine, Ala, and hexoses in the skeletal muscle were higher in sCLA than in CTR. On d 21, the changed metabolites in serum were mainly long-chain (>C24) diacyl phosphatidylcholine PC (PC-aa) and acyl-alkyl phosphatidylcholine (PC-ae), along with lysophosphatidylcholine acyl (lysoPC-a) C26:1 that were all lower in sCLA than in CTR. Supplementation with CLA affected the muscle concentrations of 22 metabolites on d 70 including 10 long-chain (>C22) sphingomyelin (SM), hydroxysphingomyelin [SM(OH)], PC-aa, and PC-ae along with 9 long-chain (>C16) lysoPC-a and 3 metabolites related to amino acids (spermine, citrulline, and Asp). On d 70, the concentrations of lysoPC-a C18:2 and C26:0 in serum were higher in the sCLA cows than in the CTR cows. Regardless of treatment, the concentrations of Ile, Leu, Phe, Lys, His, Met, Trp, and hydroxybutyrylcarnitine (C4-OH) decreased, whereas those of ornithine, Gln, and trans-4-hydroxyproline (t4-OH-Pro) increased from d 21 to 70 in muscle. The significantly changed metabolites in serum with time of lactation were 28 long-chain (>C30) PC-ae and PC-aa, 7 long-chain (>C16) SM and SM(OH), along with lysoPC-a C20:3 that were all increased. In conclusion, in addition to other significantly changed metabolites, CLA supplementation mainly led to changes in muscle and serum concentrations of glycerophospholipids and sphingolipids that might reflect the phospholipid compositional changes in muscle. The metabolome changes observed in sCLA on d 21 seem to be, at least in part, due to the lower DMI in these cows. The changes in the muscle concentrations of AA from d 21 to 70, which coincided with the steady energy and MP balances, might reflect a shift of protein synthesis/degradation balance toward synthesis.

Change in phospholipid composition and activity phospholipase A2 in hyperglycemia

The article presents data on the study of the activity of membrane phospholipase A2 of liver mitochondria, as a result of this, as you know, there is a change in the permeability of biomembranes. In the dynamics of hyperglycemia, in the body of animals, the hydrolytic activity of phospholipase A2 changes in proportion to the increase in blood sugar. The materials of the article allow us to understand the patterns of changes in the phospholipid composition, their metabolites and the activity of lipolytic enzymes of mitochondrial membranes in hyperglycemia. Here, too, the sugar-lowering and membrane-correcting effect of tincture from leaves and walnut kernels has been studied.

Metabolomic signature of the seminal plasma in men with severe oligoasthenospermia.

Male factor is incriminated in approximately 50% of cases of infertility. The metabolomic approach has recently been used in the assessment of sperm quality and male fertility. We analyzed the metabolomic signatures of the seminal plasma in 20 men with severe oligoasthenospermia (prewash total motile sperm count<5.106 ) (SOA) and compared it to 20 men with normal semen parameters, with a standardized approach of targeted and quantitative metabolomics using high-performance liquid chromatography, coupled with tandem mass spectrometry, and the Biocrates Absolute IDQ p180 kit. Among the 188 metabolites analyzed, 110 were accurately measured in the seminal plasma. A robust model discriminating the two populations (Q2(cum) = 55.2%) was obtained by OPLS-DA (orthogonal partial least-squares discriminant analysis), based on the drop in concentrations of 37 metabolites with a VIP (variable important for projection) greater than 1. Overall, in men with SOA, there was a significant decrease in: 17 phosphatidylcholines and four sphingomyelins; acylcarnitines, with free L-carnitine being the most discriminating metabolite; polyunsaturated fatty acids; six amino acids (glutamate, aspartate, methionine, tryptophan, proline, and alanine); and four biogenic amines (spermine, spermidine, serotonin, and alpha-aminoadipate). Our signature includes several metabolic changes with different impacts on the sperm quality: a change in phospholipid composition and the saturation of their fatty acids that is potentially linked to the deterioration of sperm membranes; a carnitine deficiency that can negatively impact the energy production via fatty acid oxidation and oxidative phosphorylation; and a decreased level of amino acids and biogenic amines that can lead to dysregulated metabolic and signaling pathways. We provide a global overview of the metabolic defects contributing to the structural and functional alteration of spermatozoa in severe oligoasthenospermia. These findings offer new insights into the pathophysiology of male factor infertility that could help to develop future specific treatments.

Myelin Basic Protein Phospholipid Complexation Likely Competes with Deimination in Experimental Autoimmune Encephalomyelitis Mouse Model.

Multiple sclerosis has complex pathogenesis encompassing a variety of components (immunologic, genetic, and environmental). The autoimmunogenicity against the host’s myelin basic protein is a major contributor. An increase in myelin basic protein deimination (a post-translational modification) and a change in phospholipid composition have been associated with multiple sclerosis. The interaction of myelin basic protein with phospholipids in the myelin membrane is an important contributor to the stability and maintenance of proper myelin sheath function. The study of this aspect of multiple sclerosis is an area that has yet to be fully explored and that the present study seeks to understand. Several biochemical methods, a capillary electrophoresis coupled system and mass spectrometry, were used in this study. These methods identified four specific phospholipids complexing with myelin basic protein. We show that lysophosphatidylcholine 18:1 provides a robust competitive effect against hyper-deimination. Our data suggest that lysophosphatidylcholine 18:1 has a different biochemical behavior when compared to other phospholipids and lysophosphatidylcholines 14:0, 16:0, and 18:0.

A 1D High Performance Thin Layer Chromatography Method Validated to Quantify Phospholipids Including Cardiolipin and Monolysocardiolipin from Biological Samples

AbstractThe aim of this study is to identify high performance thin layer chromatography (HPTLC) conditions allowing the separation and quantification of mammalian cellular phospholipids (PLs) (sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, and especially phosphatidic acid, cardiolipin, and monolysocardiolipin, these latter two being specifically located in mitochondria membranes). In order to make this method faster and easier, a 1D HPTLC method is chosen, testing several eluents as well as several staining methods. A pre‐conditioning of HPTLC plates with boric acid and a copper staining reagent followed by carbonization are selected for the quality of PL separation and homogeneity of staining. The selected conditions are discussed and the method validation is performed according to the International Conference on Harmonization guidelines. Linearity is effective between 1 and 8 µg and limit of quantification is between 0.5 and 2.3 µg depending on PL classes. Precision measurements show coefficients of variation &lt;6%, and when amounts are close to the detection limit, &lt;12%. Lipid extracts of tumor cell lines or isolated mitochondria are used to assess PL profiles. This shows that the HPTLC method can be used routinely to follow level variations of PLs.Practical Applications: The changes in PL composition play a crucial role in tumor processes and regulate cellular functions modulating cellular signaling or mitochondrial metabolism. The simple and cost‐effective 1D HPTLC method that is developed is applied to lipid extracts of whole tumor cells or hepatocyte‐isolated mitochondria. It is sensitive as well as precise to detect variations of phosphatidic acid or cardiolipin levels linked to physio‐pathological conditions. It can also be used to investigate the composition changes of other membrane PLs. Moreover, with a simultaneous analysis of 14 samples/standards on the same plate (six plates per day), this method is adapted for large series of samples.

Copper and iron overload protect Escherichia coli from exogenous H2O2 by modulating membrane phospholipid composition

Development of green technologies for sustainable development requires growth of bacteria in medium containing H2O2 from 50 to 150 mM that may contain millimolar level of copper (Cu) and iron (Fe). However, the mechanism of oxidative stress involving high concentration of exogenous H2O2 in bacteria and the effect of Cu and Fe overload on the same remain controversial. In the present study, we investigated the effect of millimolar concentration of Cu and Fe on H2O2-induced oxidative stress using the enterotoxigenic Escherichia coli 12566 as a model system. Our results indicate that at millimolar concentration, Fe and Cu protect E. coli from H2O2-induced oxidative stress by (1) suppressing H2O2-induced growth inhibition, (2) reducing H2O2-induced lipid peroxidation, (3) decreasing catalase activity and (4) modulating H2O2 -induced release of cytosolic Fe content in a dose-dependent manner. A previous study by our group shows that H2O2 significantly alters the phospholipid (PL) composition in E. coli by a dose-dependent increase in cardiolipin (CL) accompanied by decrease in sum total of phosphatidyl ethanolamine (PE) and phosphatidyl glycerol (PG). In the present study, we show that Cu2+ and Fe3+ at 1 mM reduce H2O2-induced change in PL composition of E. coli leading to stabilization of its membrane components. For the first time, our results show that overloading of E. coli with Cu2+ and Fe3+ activates a protective mechanism against H2O2-induced oxidative damage by modulating its membrane PL composition. Our study reveals a pivotal regulatory role of these metal ions in the sectors of sustainable technologies such as heavy metal bioremediation, sewage treatment and bioelectrochemical reactors that require microbial growth at high concentration of H2O2.

Changes in lipid composition and lipid peroxidation products content in the freshwater mussel Anodonta cygnea L. under cadmium effect

In order to identify specific biomarkers to cadmium-induced oxidative stress in freshwater organisms, changes in the composition of membrane and storage lipids and their fatty acids in the gills and digestive glands of freshwater mussels, Anodonta cygnea (Linnaeus, 1758), exposed to cadmium ions at 10, 50 and 100 µg/L were studied. Cadmium-induced oxidative stress was estimated by the content of lipid peroxidation products such as conjugated dienes and trienes, malondialdehyde, and Schiff bases. Accumulation of lipid peroxidation products in the gills and digestive glands reflected the intensity of lipid peroxidation, depending on the concentration and duration of cadmium exposure. Changes in the fatty acid composition of phospholipids and triacylglycerols reflected their compensatory role in the response of the mussels to the action of cadmium at various concentrations. Some indices of lipid composition (phosphatidylserine and triacylglycerol content) similarly altered under cadmium effect in both marine and freshwater mussels. The assessment of oxidative stress biomarkers and the main targets for these oxidative processes including lipids and their fatty acid composition makes it possible to identify protective biochemical mechanisms providing the high resistance of mussels to environmental pollution.

SWATH-MS quantitative proteomic investigation of nitrogen starvation in Arabidopsis reveals new aspects of plant nitrogen stress responses

Nitrogen is an essential macronutrient for plant growth and crop productivity. The aim of this work was to further investigate the molecular events during plant adaptation to nitrogen stress. Here, we present a SWATH-MS (Sequential window acquisition of all theoretical mass spectra)-based quantitative approach to detect proteome changes in Arabidopsis seedlings following nitrogen starvation. In total, 736 proteins of diverse functions were determined to show significant abundance changes between nitrogen-supplied and nitrogen-starved Arabidopsis seedlings. Functional categorization revealed the involvement of nitrogen stress-responsive proteins in biological processes including amino acid and protein metabolism, photosynthesis, lipid metabolism and glucosinolate metabolism. Subsequent phospholipid profiling of Arabidopsis seedlings showed changes in phospholipid composition that may enhance membrane fluidity as a response to nitrogen starvation. Moreover, an Arabidopsis grf6 T-DNA insertion mutant was found to have a nitrogen stress-sensitive phenotype. GRF6 is a 14-3-3 protein with elevated abundance upon nitrogen starvation and it may function as a positive regulator during nitrogen stress adaptation.

Mass Spectrometry Imaging Shows Cocaine and Methylphenidate Have Opposite Effects on Major Lipids in Drosophila Brain.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to study the effects of cocaine versus methylphenidate administration on both the localization and abundance of lipids in Drosophila melanogaster brain. A J105 ToF-SIMS with a 40 keV gas cluster primary ion source enabled us to probe molecular ions of biomolecules on the fly with a spatial resolution of ∼3 μm, giving us unique insights into the effect of these drugs on molecular lipids in the nervous system. Significant changes in phospholipid composition were observed in the central brain for both. Principal components image analysis revealed that changes occurred mainly for phosphatidylcholines, phosphatidylethanolamines, and phosphatidylinositols. When the lipid changes caused by cocaine were compared with those induced by methylphenidate, it was shown that these drugs exert opposite effects on the brain lipid structure. We speculate that this might relate to the molecular mechanism of cognition and memory.

Influence of phosphatidylserine and phosphatidylethanolamine on farnesol tolerance in Candida albicans.

Candida albicans is among the most common human fungal pathogens. The ability to undergo the morphological transition from yeast to hyphal growth is critical for its pathogenesis. Farnesol, a precursor in the isoprenoid/sterol pathway, is a quorum-sensing molecule produced by C. albicans that inhibits hyphal growth in this polymorphic fungus. Interestingly, C. albicans can tolerate farnesol concentrations that are toxic to other fungi. We hypothesized that changes in phospholipid composition are one of the factors contributing to farnesol tolerance in C. albicans. In this study, we found that loss of enzymes that synthesize the phospholipids phosphatidylserine (PS) and/or phosphatidylethanolamine (PE) compromise the tolerance of C. albicans to farnesol. Compared with wild type, the phospholipid mutant cho1∆/∆ (loss of PS and decreased PE synthesis) shows greater inhibition of growth, loss of ATP production, increased consumption of oxygen, and increased formation of reactive oxygen species in the presence of farnesol. The cho1∆/∆ mutant also exhibits decreased sensitivity to mitochondrial ATPase inhibition, suggesting that cells lacking PS and/or downstream PE rely less on mitochondrial function for ATP synthesis. These data reveal that PS and PE play roles in farnesol tolerance and maintaining mitochondrial respiratory function.

Dimebon correction of changes in phospholipid composition induced by tumor necrosis factor-alpha in experement

To investigate the ability of the neuroprotector dimebon to prevent alterations in brain lipid metabolism caused byTNF-α. The ability of dimebon (2,8-Dimethyl-5-[2-(6-methyl-3-pyridinyl)ethyl]-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole hydrochloride) to prevent alterations in brain lipid metabolism caused byTNF-α was studied in 65 male mice (20+2g weight). TNF-α (10 mkg/mouse), dimebon (0.2 mg/kg) and their combination were injected intraperitoneally. Thirty min, 2, 4 and 24 h after injection, lipid level alterations in total fractions and molecular species of phospholipids (phosphatidylcholine, lysophosphatidylcholine, sphingomyelin and phosphatidylethanolamine) were measured with mass-spectrometry in the hippocampus, cortex and cerebellum. After injection of TNF-α into mice, there are significant changes in the level of all tested phospholipids. Dimebon at a dose of 0.2 mg/kg alone does not cause any changes in the content of all tested phospholipids, but injected together with TNF-α prevents cytokine induced alterations in the lipid content. The selectivity of TNF-α and dimebon influence on certain molecular species of various phospholipids in different parts of mouse brain is found. The presented data suggest protective properties of dimebon preventing the development of proinflammatory syndrome induced by TNF-α in the animal brain.

Unraveling the causes of arrhythmias in very-long chain acyl-CoA (VLCAD) deficiency through the combined use of non-targeted lipidomic and molecular analyses in a mouse model

VLCAD catalyses the first reaction of mitochondrial fatty acids (FA) β-oxidation. Inherited VLCAD deficiency predisposes to severe neonatal arrhythmias whose pathophysiology is not fully understood. We hypothesized that VLCAD deficiency disrupts cardiac lipid homeostasis, which could contribute to arrhythmia. Our study model is the VLCAD null mouse (VLCAD −/− ), which is known to develop a prolonged QT interval and ventricular arrhythmias. Mice were fed a chow or high fat (HF) diet, the latter being known to worsen the cardiac phenotype in VLCAD deficiency. Non-targeted lipidomic profiling of heart tissues was achieved using liquid chromatography-mass spectrometry (LC-QTOF). The expression of genes or proteins involved in polyunsaturated FA synthesis, phospholipid (PL) remodeling, endoplasmic reticulum (ER) stress and calcium handling were assessed using RT-qPCR or Western blotting. Compared to their littermate counterparts, VLCAD −/− mouse hearts displayed alterations in the FA composition of PL characterised by an increase in arachidonic acid and a decrease in docosahexaenoic acid, a profile that was worsened with the HF diet. These changes in PL composition were associated with diet-dependent increased expression of gene or protein markers for (1) PL remodeling, especially the calcium-dependent phospholipase A2 and the lysophosphatidylcholine-acyltransferase 2, (2) ER stress, namely CHOP and GRP78, and (3) calcium handling, namely SERCA2a and phospholamban (PLB). In contrast, the phosphorylated form of PLB (Ser16) and RyR2 (Ser2808) was decreased. Altogether, results from this study highlight perturbations in PL remodeling in VLCAD −/− mouse hearts, which are associated with ER stress and alterations in proteins involved in calcium handling and exacerbated by a HF diet. These perturbations represent novel potential mechanisms, which could contribute to the pathogenesis of arrhythmias in VLCAD −/− mice as well as in humans.

MJ4-M4 - Unraveling the causes of arrhythmias in very-long chain acyl-CoA dehydrogenase (VLCAD) deficiency through the combined use of nontargeted lipidomic and molecular analyses in a mouse model

Background VLCAD catalyses the first reaction of mitochondrial fatty acids (FA) β-oxidation. Inherited VLCAD deficiency predisposes to severe neonatal arrhythmias whose pathophysiology is not fully understood. We hypothesized that VLCAD deficiency disrupts cardiac lipid homeostasis, which could contribute to arrhythmia. Methods Our study model is the VLCAD null mouse (VLCAD−/−), which is known to develop a prolonged QT interval and ventricular arrhythmias. Mice were fed a chow or high fat (HF) diet, the latter being known to worsen the cardiac phenotype in VLCAD deficiency. Non-targeted lipidomic profiling of heart tissues was achieved using liquid chromatography-mass spectrometry (LC-QTOF). The expression of genes or proteins involved in polyunsaturated FA synthesis, phospholipid (PL) remodeling, endoplasmic reticulum (ER) stress and calcium handling were assessed using RT-qPCR or Western blotting. Results Compared to their littermate counterparts, VLCAD−/− mouse hearts displayed alterations in the FA composition of PL characterised by an increase in arachidonic acid and a decrease in docosahexaenoic acid, a profile that was worsened with the HF diet. These changes in PL composition were associated with diet-dependent increased expression of gene or protein markers for (1) PL remodeling, especially the calcium-dependent phospholipase A2 and the lysophosphatidylcholine-acyltransferase 2, (2) ER stress, namely CHOP and GRP78, and (3) calcium handling, namely SERCA2a and phospholamban (PLB). In contrast, the phosphorylated form of PLB (Ser16) and RyR2 (Ser2808) was decreased. Conclusion Altogether, results from this study highlight perturbations in PL remodeling in VLCAD−/− mouse hearts, which are associated with ER stress and alterations in proteins involved in calcium handling and exacerbated by a HF diet. These perturbations represent novel potential mechanisms, which could contribute to the pathogenesis of arrhythmias in VLCAD−/− mice as well as in humans.