Phospholipid Composition Research Articles

The effect of cardiolipin side chain composition on cytochrome c protein conformation and peroxidase activity.

Skeletal muscle, a highly active tissue, makes up 40% of the total body weight. This tissue relies on mitochondria for ATP production, calcium homeostasis, and programed cell death. Mitochondrial phospholipid composition, namely, cardiolipin (CL), influences the functional efficiency of mitochondrial proteins, specifically cytochrome c. The interaction of CL with cytochrome c in the presence of free radicals induces structural and functional changes promoting peroxidase activity and cytochrome c release, a key event in the initiation of apoptosis. The CL acyl chain degree of saturation has been implicated in the cytochrome c to cytochrome c peroxidase transition in liposomal models. However, mitochondrial membranes are composed of differing CL acyl chain composition. Currently, it is unclear how differing CL acyl chain composition utilizing liposomes will influence the cytochrome c form and function as a peroxidase. Thus, this study examined the role of CL acyl chain saturation within liposomes broadly reflecting the relative CL composition of mitochondrial membranes from healthy and dystrophic mouse muscle on cytochrome c conformation and function. Despite no differences in protein conformation or function between healthy and dystrophic liposomes, cytochrome c's affinity to CL increased with greater unsaturation. These findings suggest that increasing CL acyl chain saturation, as implicated in muscle wasting diseases, may not influence cytochrome c transformation and function as a peroxidase but may alter its interaction with CL, potentially impacting further downstream effects.

Effect of enzyme on the demulsification of emulsion during aqueous enzymatic extraction and the corresponding mechanism

AbstractBackgrounds and objectivesEmulsion is formed during the aqueous enzymatic extraction (AEE) of peanut oil and protein. Protein and phospholipid, the main emulsifiers, play an important role in the stability of this emulsion. In this study, phospholipase A1, phospholipase A2, phospholipase D, papain, or Alcalase 2.4 L was used as demulsification agents. The phospholipid composition, interfacial protein concentration and composition, viscosity, particle diameter distribution, and microstructure of the emulsion during demulsification were evaluated.FindingsNuclear magnetic resonance analysis showed that the content of phosphatidylcholine decreased by 12.3% after treatment with the three phospholipases, whereas the content of phosphatidic acid increased 9 times. Treatment with protease caused the molecular weight of interfacial proteins and the viscosity of the emulsion significantly decreased, and the average particle diameter increased 8 times.ConclusionsThe free oil yields obtained using PLA1, PLA1/PLA2, PLD, Alcalase 2.4 L, and papain were 45.6%, 85.3%, 30.7%, 84.3%, and 93.8%, respectively. Papain destroyed the interfacial membrane of the emulsion and had the best demulsification effect.Significance and noveltyThe findings solve the problem of difficult demulsification during the extraction of peanut oil by AEE and provide a theoretical basis for the large‐scale industrial application of the demonstrated demulsification method.

The effect of choline availability from gestation to early development on brain and retina functions and phospholipid composition in a male mouse model

ABSTRACT Objectives Although choline is essential for brain development and neural function, the effect of choline on retina function is not well understood. This study examined the effects of choline on neural tissues of brain and retina, and membrane phospholipid (PL) composition during fetal development. Methods Pregnant C57BL/6 mice were fed one of 4 choline modified diets: i) control (Cont, 2.5g/kg), ii) choline deficient (Def, 0g/kg), iii) supplemented with choline chloride (Cho, 10g/kg) and iv) supplemented with egg phosphatidylcholine (PC, 10g/kg). At postnatal day (PD) 21, pups were weaned onto their mothers’ respective diets until PD 45. Spatial memory was measured using the Morris Water Maze; retina function by electroretinogram (ERG); and PL composition with nuclear magnetic resonance spectroscopy. Results Cho and PC supplementation enhanced cued learning and spatial memory abilities, respectively (p Def > PC > Cho, with no statistically significant alterations in cone-driven responses. There were no differences in the composition of major PLs in the brain and retina. In the brain, subclasses of ether PL, alkyl acyl- phosphatidylethanolamine (PEaa) and phosphatidylcholine (PCaa) were significantly greater among the PC supplemented group in comparison to the Def group. Discussion These results indicate that while choline supplementation during gestation to an early developmental period is beneficial for spatial memory, contributions to retina function are minor. Assessment with a larger sample size of retinas could warrant the essentiality of choline for retina development.

Red Blood Cell Fatty Acids and Risk of Colorectal Cancer in The European Prospective Investigation into Cancer and Nutrition (EPIC).

A growing body of evidence suggests that alterations of dietary fatty acid (FA) profiles are associated with colorectal cancer risk. However, data from large-scale epidemiologic studies using circulating FA measurements to objectively assess individual FA and FA categories are scarce. We investigate the association between red blood cell (RBC) membrane FAs and risk of colorectal cancer in a case-control study nested within a large prospective cohort. After a median follow-up of 6.4 years, 1,069 incident colorectal cancer cases were identified and matched to 1,069 controls among participants of the European Prospective Investigation into Cancer and Nutrition (EPIC). The FA composition of RBC phospholipids (in mol%) was analyzed by gas chromatography, and their association with risk of colorectal cancer was estimated by multivariable adjusted conditional logistic regression models. After correction for multiple testing, subjects with higher concentrations of RBC stearic acid were at higher risk for colorectal cancer (OR = 1.23; 95% CI = 1.07-1.42, per 1 mol%). Conversely, colorectal cancer incidence decreased with increasing proportions of RBC n-3 PUFA, particularly eicosapentaenoic acid (0.75; 0.62-0.92, per 1 mol%). The findings for the n-6 PUFA arachidonic acid were inconsistent. The positive association between prediagnostic RBC stearic acid and colorectal cancer reflects putative differences in FA intake and metabolism between cancer cases and matched controls, which deserve further investigation. The inverse relationship between EPA and colorectal cancer is in line with the repeatedly reported protective effect of fish consumption on colorectal cancer risk. These findings add to the evidence on colorectal cancer prevention.

Metabolic Potential, Ecology and Presence of Associated Bacteria Is Reflected in Genomic Diversity of Mucoromycotina.

Mucoromycotina are often considered mainly in pathogenic context but their biology remains understudied. We describe the genomes of six Mucoromycotina fungi representing distant saprotrophic lineages within the subphylum (i.e., Umbelopsidales and Mucorales). We selected two Umbelopsis isolates from soil (i.e., U. isabellina, U. vinacea), two soil-derived Mucor isolates (i.e., M. circinatus, M. plumbeus), and two Mucorales representatives with extended proteolytic activity (i.e., Thamnidium elegans and Mucor saturninus). We complement computational genome annotation with experimental characteristics of their digestive capabilities, cell wall carbohydrate composition, and extensive total lipid profiles. These traits inferred from genome composition, e.g., in terms of identified encoded enzymes, are in accordance with experimental results. Finally, we link the presence of associated bacteria with observed characteristics. Thamnidium elegans genome harbors an additional, complete genome of an associated bacterium classified to Paenibacillus sp. This fungus displays multiple altered traits compared to the remaining isolates, regardless of their evolutionary distance. For instance, it has expanded carbon assimilation capabilities, e.g., efficiently degrades carboxylic acids, and has a higher diacylglycerol:triacylglycerol ratio and skewed phospholipid composition which suggests a more rigid cellular membrane. The bacterium can complement the host enzymatic capabilities, alter the fungal metabolism, cell membrane composition but does not change the composition of the cell wall of the fungus. Comparison of early-diverging Umbelopsidales with evolutionary younger Mucorales points at several subtle differences particularly in their carbon source preferences and encoded carbohydrate repertoire. Nevertheless, all tested Mucoromycotina share features including the ability to produce 18:3 gamma-linoleic acid, use TAG as the storage lipid and have fucose as a cell wall component.

Abstract PS17-26: Fatty acid synthase inhibition targets ERα in tamoxifen-resistant breast cancer

Abstract INTRODUCTION: Estrogen receptor-positive (ER+) breast cancer accounts for nearly 70% of all cases. Common targeted anti-estrogen therapies such tamoxifen, fulvestrant and aromatase inhibitors have shown success in the clinic, but unfortunately, often lead to resistance. The fatty acid synthase enzyme (FASN) is responsible for endogenously synthesizing long-chain fatty acids, such as palmitate, which can contribute to protein modification, phospholipid biosynthesis for membranes, and lipid raft signaling that favors tumorigenesis. The depletion of intracellular palmitate leads to an alteration of lipid composition within lipid rafts of the plasma membrane as well as lipids within the endoplasmic reticulum membrane. Endoplasmic reticulum stress elicits an inhibition of protein translation through the phosphorylation of eukaryotic initiating factor 2-α (p-eIF2α) and is activated by various stimuli including altered phospholipid composition within the membrane. Our preliminary findings illustrated a degradation of the ERα upon treatment with the FASN inhibitor, TVB-3166, in tamoxifen-resistant breast cancer both in vivo and in vitro. Moreover, previous studies have illustrated FASN inhibition to induce endoplasmic reticulum stress concomitant with a loss of the androgen receptor (AR) in castration-resistant prostate cancer. Additionally, palmitate treatment rescued AR expression that was accompanied by an attenuation in endoplasmic reticulum stress. HYPOTHESIS: We hypothesize FASN inhibition leads to a degradation of ERα in tamoxifen-resistant breast cancer through the induction of endoplasmic reticulum stress. METHODS: Patient tumor explants were incubated for 72h on gelatin sponges in culture medium in the absence or presence of 200nM TVB-3166. Tissue were fixed in 10% formalin and processed into paraffin blocks and stained for ERα and Ki67. To investigate TVB induced endoplasmic reticulum stress, tamoxifen-Resistant (TamR) MCF-7 and MCF-7 cells were treated with TVB-3166 or vehicle control followed by treatment with either palmitate or ER stress inhibitor, 1,2-Bis(2-Aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA). Expression of ERα, p-eIF2α, eIF2α were measured by western blot. RESULTS: TVB-3166 treatment of primary tumor explants decreased their proliferation (Ki67) compared to untreated controls (14% vs 36%, p<0.01). Both IHC and Western blotting demonstrated a reduction in ERα upon treatment with TVB-3166. In addition to the decreased expression of ERα, there was an increase in the phosphorylation of eukaryotic initiation factor 2α (p-eIF2α). The expression of ERα was rescued upon palmitate treatment while resulting in decreased p-eIF2α. Inhibition of endoplasmic stress using BAPTA also rescued ERα expression after TVB-3166 treatment. CONCLUSION: FASN is a potentially viable target in tamoxifen-resistant breast cancer. Citation Format: Bryan Mcclellan, Aleksandra Gruslova, Christopher Jolly, Linda deGraffenried, Andrew Brenner. Fatty acid synthase inhibition targets ERα in tamoxifen-resistant breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-26.

Computational Studies of Lipid-Wrapped Gold Nanoparticle Transport Through Model Lung Surfactant Monolayers.

Colloidal nanoparticles, such as gold nanoparticles (AuNPs), are promising materials for the delivery of hydrophilic drugs via the pulmonary route. The inhaled nanoparticle drug carriers primarily deposit in lung alveoli and interact with the alveolar surface known as lung surfactants. Therefore, it is vital to understand the interactions of nanocarriers with the surfactant layer. To understand the interactions at the molecular level, here we simulated model lung surfactant monolayers with phospholipid (PL)-wrapped AuNPs at the vacuum-water interface using coarse-grained molecular dynamics simulations. The PL-wrapped AuNPs quickly adsorbed into the surfactant layer, altered the structural properties of the monolayer, and at high concentrations initiated the compressed monolayer to collapse/buckle. Among the surfactant monolayer lipid components, cholesterol adsorbed to the AuNPs preferentially over PL species. The position of the adsorbed PL-AuNPs within the monolayer, and subsequent monolayer perturbation, vary depending on the monolayer phase, monolayer composition, and species of PL used as a ligand. Information provided by these molecular dynamic simulations helps to rationalize why some colloidal nanoparticles work better as nanocarriers than others and aid the design of new ones, to avoid biological toxicity and improve efficacy for pulmonary drug delivery.

Alterationsin Membrane Lipids of Live Red Blood Cellsaffecttheir Interactions with Exogenous Particles

The mammalian cell membrane is a lipid bilayer, which is asymmetric with respect to its phospholipid composition. Cyclodextrins, a group of cyclic molecules with a highly hydrophobic cavity and hydrophilic exterior, have been shown to mediate the exchange of exogenous phospholipids with bilayer membranes. We previously implemented this method to report the type and species of phospholipids in the outer leaflet of red blood cells (RBCs). In this study, we use phospholipid exchange to elucidate the role of phospholipids in nanoparticle interactions with RBC membranes. We exchanged the outer leaflet of RBCs with phospholipids of interest, using methyl-α-cyclodextrin and studied nanoparticles interaction with the membrane. Multiple phospholipids, including sphingomyelins (SM), phosphatidylcholines (PC), and phosphatidylserines (PS), in different molar ratios, were delivered to the outer leaflet to study the effects of different lipid headgroups on RBC-nanoparticle interactions. Delivery of the phospholipids to the RBC membrane was confirmed using fluorescence microscopy and thin layer chromatography. RBC hemolysis after interaction with nanoparticles was measured as an indicator of membrane perturbation. Fluorescence anisotropy of the RBC membrane was also used to show how the lipid packing changes after lipid exchange and during interactions with nanoparticles, while flow cytometry was utilized as a measure of binding of nanoparticles to the RBCs. The results showed high disruption of RBCs when the outer leaflet consisted solely of SM or PC. In contrast, when PS was the sole constituent of the outer leaflet, nanoparticle disruption of the cells was negligible. These results are important in understanding the role of membrane lipid composition in cell-material interactions.

Electrostatic Effects on Model Membrane Compressibility and Vesicle Adhesion

Though vesicles are recognized as effective drug carriers and functionalized with polymers, targeting ligands, imaging agents, and antibodies for drug delivery applications, there is minimal knowledge of the role of lipid bilayer properties in a vesicle's ability to interact with target membranes. Phospholipids within the cellular lipid membrane are chemically diverse, with tail lengths, saturation, and headgroup chemistry varying depending on tissue function and health condition. These function and status dependent compositional observations raise questions on how the underlying membrane properties, such as thickness, fluidity, and compressibility, alter biophysical processes and regulate the transport of vesicles across the membrane. In this work we use compositionally controlled, free-standing large area model biomembranes (LAMB) as an artificial platform to investigate the ramifications of altered phospholipid composition on vesicle-membrane interactions. First, simultaneous area and capacitance measurements of the LAMB allow us to determine the thickness and Young's modulus (compressibility) of a given membrane of varied compositions. In particular, we focus on the effect of headgroup charge, which shows that increasing anionic phospholipid composition increases the membrane stiffness. Next, small (100nm) vesicles composed of DOPC, DOPE, and DOPE-Rh are introduced and subsequently electrostatically adhered to the LAMB. We use Ca2+ ions as a trigger to initiate fusion between the adhered vesicles and LAMB while monitoring fluorescence and capacitance. We observe interesting morphological changes at the membrane interface such as vesicle-vesicle fusion, formation of worm-like vesicle aggregates, and vesicle-membrane fusion. Current work is focused analyzing these events and calculating the activation energy of membrane fusion by simultaneous fluorescence and capacitance measurements. Characterizing the relationship between energy of fusion and vesicle/membrane composition will provide a basis for the rational design of vesicles for targeted membrane interaction.

Morphological and Nanomechanical Properties of Model of Animal and Human Eye Lens Lipid Membranes

The four major phospholipids found in eye lens membrane are phosphatidylcholine (PC), sphingomyelin (SM), phosphatidylethanolamine (PE), and phosphatidylserine (PS). Lens lipid composition of the fiber-cell membrane significantly changes with species. In lower-age animals, phosphatidylcholine (PC) is dominant, whereas, in humans, sphingomyelin (SM) is more dominant. We have used atomic force microscopy (AFM) to study morphological and nanomechanical properties of the lens lipid membrane models from mouse, pig, and humans. Small unilamellar vesicles (SUVs) were prepared from the mixture of four phospholipids (PC, SM, PS, and PE) that resemble mouse, pig, and human phospholipid composition lens membranes. The SUVs phospholipids mixtures were prepared with 0 mol% and 50 mol% of cholesterol. The topographical image and the mechanical properties of animal and human lens model membranes were accessed in a supported lipid membrane (SLM) formed on mica. The topographical images of phospholipid mixtures with 0 mol% cholesterol for both animal and human lens membrane models exhibited coexisting solid-ordered and liquid-disordered phase, where the proportion of solid-ordered phase increases with an increase in SM content in phospholipid mixture. The height difference between the two phases was ∼ 1nm. However, in the presence of 50 mol% of cholesterol, the membrane exhibited only a liquid-ordered phase, both for animal and human phospholipid mixtures. The breakthrough force on the SLM of the animals and human lens model membrane obtained with 50 mol% of cholesterol follow the trends: F (human) > F (pig) > F (mouse). Similarly, the membrane area compressibility modulus (Ka) of the membrane with 50 mol% cholesterol was accessed using the force curve's elastic regime. We found: Ka (human) > Ka (pig) > Ka (mouse). Our results show that phospholipid composition plays a significant role in modulating membrane mechanical properties.

Challenging the Dogma - Cell Plasma Membranes are Asymmetric not only in Phospholipid Composition but also Abundance

The transbilayer distribution of lipids in mammalian plasma membranes (PMs) is functionally important and incompletely understood. It has been generally assumed that the two PM leaflets contain similar number of phospholipids (PLs) due to the constraint that their areas must be matched in a bilayer. Contrary to this widely held assumption, our recent detailed lipidomics analysis of human erythrocytes reveals a large phospholipid imbalance between PM leaflets, with the cytoplasmic leaflet possessing almost 2-fold more PLs as the exoplasmic one. This surprising finding is consistent with several previous observations and challenges our understanding of living membrane organization and structure. To investigate the effects of differential PL abundance on membrane properties, we performed long atomistic molecular dynamics simulations of various PM models with data-driven leaflet compositions and different PL imbalances between the leaflets. The integrity of the bilayer was preserved in part by (re)distribution of the PM's other major component, cholesterol, which shows a strong preference for the exoplasmic leaflet. Detailed leaflet-specific analysis of the physical properties of the membranes revealed systematic changes as the relative number of PLs in the exoplasmic leaflet decreased. These changes were accompanied by differences in the water permeability of the leaflets, their pressure distribution and propensity for hydrophobic defects. To determine which PM model most closely represents the cell PM we calibrated an in vitro reporter of membrane packing to simulations using experimental measurements of model membranes, and compared the simulated models to live cells PMs. Our results were consistent with a model of living PMs with far more cholesterol and fewer PLs in the exoplasmic leaflet. They also reveal a substantial amount of stored tension in the bilayer leaflets, uncovering a host of previously unconsidered physiological implications.

Thermal profiles reveal stark contrasts in properties of biological membranes from heart among Antarctic notothenioid fishes which vary in expression of hemoglobin and myoglobin

Antarctic notothenioids are noted for extreme stenothermy, yet underpinnings of their thermal limits are not fully understood. We hypothesized that properties of ventricular membranes could explain previously observed differences among notothenioids in temperature onset of cardiac arrhythmias and persistent asystole. Microsomes were prepared using ventricles from six species of notothenioids, including four species from the hemoglobin-less (Hb-) family Channichthyidae (icefishes), which also differentially express cardiac myoglobin (Mb), and two species from the (Hb+) Nototheniidae. We determined membrane fluidity and structural integrity by quantifying fluorescence depolarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and leakage of 5(6)-carboxyfluorescein, respectively, over a temperature range from ambient (0°C) to 20°C. Compositions of membrane phospholipids and cholesterol contents were also quantified. Membranes from all four species of icefishes exhibited greater fluidity than membranes from the red-blooded species N. coriiceps. Thermal sensitivity of fluidity did not vary among species. The greatest thermal sensitivity to leakage occurred between 0 and 5°C for all species, while membranes from the icefish, Chaenocephalus aceratus (Hb-/Mb-) displayed leakage that was nearly 1.5-fold greater than leakage in N. coriiceps (Hb+/Mb+). Contents of phosphatidylethanolamine (PE) were approximately 1.5-fold greater in icefishes than in red-blooded fishes, and phospholipids had a higher degree of unsaturation in icefishes than in Hb+notothenioids. Cholesterol contents were lowest in Champsocephalus gunnari (Hb-/Mb-) and highest in the two Hb+/Mb+species, G. gibberifrons and N. coriiceps. Our results reveal marked differences in membrane properties and indicate a breach in membrane fluidity and structural integrity at a lower temperature in icefishes than in red-blooded notothenioids.

Alterations in cellular and organellar phospholipid compositions of HepG2 cells during cell growth

The human hepatoblastoma cell line, HepG2, has been used for investigating a wide variety of physiological and pathophysiological processes. However, less information is available about the phospholipid metabolism in HepG2 cells. In the present report, to clarify the relationship between cell growth and phospholipid metabolism in HepG2 cells, we examined the phospholipid class compositions of the cells and their intracellular organelles by using enzymatic fluorometric methods. In HepG2 cells, the ratios of all phospholipid classes, but not the ratio of cholesterol, markedly changed with cell growth. Of note, depending on cell growth, the phosphatidic acid (PA) ratio increased and phosphatidylcholine (PC) ratio decreased in the nuclear membranes, the sphingomyelin (SM) ratio increased in the microsomal membranes, and the phosphatidylethanolamine (PE) ratio increased and the phosphatidylserine (PS) ratio decreased in the mitochondrial membranes. Moreover, the mRNA expression levels of enzymes related to PC, PE, PS, PA, SM and cardiolipin syntheses changed during cell growth. We suggest that the phospholipid class compositions of organellar membranes are tightly regulated by cell growth. These findings provide a basis for future investigations of cancer cell growth and lipid metabolism.

Effects of Varying Dietary Docosahexaenoic, Eicosapentaenoic, Linoleic, and α-Linolenic Acid Levels on Fatty Acid Composition of Phospholipids and Neutral Lipids in the Liver of Atlantic Salmon, Salmo salar

Fish oil, the most abundant natural source of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), is a limited resource; however, terrestrial oils are used as an alternative in fish nutrition. The liver of Atlantic salmon is able to synthesize these two long-chain n-3 polyunsaturated fatty acids (n-3LC-PUFAs) from α-linolenic acid (ALA), but the dietary levels of EPA + DHA and the ratios of linoleic acid (LNA) to ALA may affect its abilities. Feeding Atlantic salmon four experimental diets containing EPA + DHA at 0.3 and 1.0% of dietary levels accompanied with high and low LNA/ALA ratios showed that low LNA/ALA ratios increased the proportions of EPA + DHA in phospholipids (PLs) and neutral lipids (NLs). The pattern of PL-to-NL ratios of n-3 LC-PUFA proportions matched the saw tooth pattern of LNA/ALA ratios in diets. Overall, when fish oil is removed from salmon diets, the dietary LNA/ALA ratio must be reduced to stimulate biosynthesis of n-3 LC-PUFAs in the liver.

Molecular Basis of the Anticancer and Antibacterial Properties of CecropinXJ Peptide: An In Silico Study.

Esophageal cancer is an aggressive lethal malignancy causing thousands of deaths every year. While current treatments have poor outcomes, cecropinXJ (CXJ) is one of the very few peptides with demonstrated in vivo activity. The great interest in CXJ stems from its low toxicity and additional activity against most ESKAPE bacteria and fungi. Here, we present the first study of its mechanism of action based on molecular dynamics (MD) simulations and sequence-property alignment. Although unstructured in solution, predictions highlight the presence of two helices separated by a flexible hinge containing P24 and stabilized by the interaction of W2 with target biomembranes: an amphipathic helix-I and a poorly structured helix-II. Both MD and sequence-property alignment point to the important role of helix I in both the activity and the interaction with biomembranes. MD reveals that CXJ interacts mainly with phosphatidylserine (PS) but also with phosphatidylethanolamine (PE) headgroups, both found in the outer leaflet of cancer cells, while salt bridges with phosphate moieties are prevalent in bacterial biomimetic membranes composed of PE, phosphatidylglycerol (PG) and cardiolipin (CL). The antibacterial activity of CXJ might also explain its interaction with mitochondria, whose phospholipid composition recalls that of bacteria and its capability to induce apoptosis in cancer cells.

DNA methylation and lipid metabolism: an EWAS of 226 metabolic measures

BackgroundThe discovery of robust and trans-ethnically replicated DNA methylation markers of metabolic phenotypes, has hinted at a potential role of epigenetic mechanisms in lipid metabolism. However, DNA methylation and the lipid compositions and lipid concentrations of lipoprotein sizes have been scarcely studied. Here, we present an epigenome-wide association study (EWAS) (N = 5414 total) of mostly lipid-related metabolic measures, including a fine profiling of lipoproteins. As lipoproteins are the main players in the different stages of lipid metabolism, examination of epigenetic markers of detailed lipoprotein features might improve the diagnosis, prognosis, and treatment of metabolic disturbances.ResultsWe conducted an EWAS of leukocyte DNA methylation and 226 metabolic measurements determined by nuclear magnetic resonance spectroscopy in the population-based KORA F4 study (N = 1662) and replicated the results in the LOLIPOP, NFBC1966, and YFS cohorts (N = 3752). Follow-up analyses in the discovery cohort included investigations into gene transcripts, metabolic-measure ratios for pathway analysis, and disease endpoints. We identified 161 associations (p value < 4.7 × 10−10), covering 16 CpG sites at 11 loci and 57 metabolic measures. Identified metabolic measures were primarily medium and small lipoproteins, and fatty acids. For apolipoprotein B-containing lipoproteins, the associations mainly involved triglyceride composition and concentrations of cholesterol esters, triglycerides, free cholesterol, and phospholipids. All associations for HDL lipoproteins involved triglyceride measures only. Associated metabolic measure ratios, proxies of enzymatic activity, highlight amino acid, glucose, and lipid pathways as being potentially epigenetically implicated. Five CpG sites in four genes were associated with differential expression of transcripts in blood or adipose tissue. CpG sites in ABCG1 and PHGDH showed associations with metabolic measures, gene transcription, and metabolic measure ratios and were additionally linked to obesity or previous myocardial infarction, extending previously reported observations.ConclusionOur study provides evidence of a link between DNA methylation and the lipid compositions and lipid concentrations of different lipoprotein size subclasses, thus offering in-depth insights into well-known associations of DNA methylation with total serum lipids. The results support detailed profiling of lipid metabolism to improve the molecular understanding of dyslipidemia and related disease mechanisms.

Obese mother offspring have hepatic lipidic modulation that contributes to sex-dependent metabolic adaptation later in life

With the increasing prevalence of obesity in women of reproductive age, there is an urgent need to understand the metabolic impact on the fetus. Sex-related susceptibility to liver diseases has been demonstrated but the underlying mechanism remains unclear. Here we report that maternal obesity impacts lipid metabolism differently in female and male offspring. Males, but not females, gained more weight and had impaired insulin sensitivity when born from obese mothers compared to control. Although lipid mass was similar in the livers of female and male offspring, sex-specific modifications in the composition of fatty acids, triglycerides and phospholipids was observed. These overall changes could be linked to sex-specific regulation of genes controlling metabolic pathways. Our findings revised the current assumption that sex-dependent susceptibility to metabolic disorders is caused by sex-specific postnatal regulation and instead we provide molecular evidence supporting in utero metabolic adaptations in the offspring of obese mothers.

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.

Micromycete Lipids and Stress

Among the living organisms, microscopic fungi are unique in their ability to occupy diverse ecological niches due to the evolutionarily formed mechanisms of adaptation to a broad range of climatic and technogenic factors. One approach to understanding the mechanisms of adaptation to changing environmental conditions is associated with lipid metabolism. The review provides a critical analysis of publications and our own experimental data on the variability of micromycete lipids under the influence of stress factors and of the possible related adaptive mechanisms. The functional, structural, and quantitative changes in fungal lipids were analyzed under the conditions of osmotic, thermal, and cold influences, as well as toxicity. Biochemical variations in the composition of phospholipids and other membrane lipids are characterized as diverse and ambiguous, depending on the degree of exposure, the initial lipid composition, genetic resistance of fungi, and their ability to adapt to extreme conditions. The role of lipid metabolism in the overall integral response of fungal cells to stress is discussed.

Negatively charged phospholipids stimulate factor XI activation by thrombin

IntroductionCoagulation factor XI (FXI) is the zymogen of the serine-protease FXIa, which contributes to thrombin formation by activating factor IX. FXI can be activated by factor XIIa or thrombin, but thrombin-catalysed FXI activation is highly inefficient, unless stimulated by polyanions such as dextran sulphate (DXS) or polyphosphate (PolyP). AimTo investigate whether negatively charged phospholipids can also enhance thrombin-catalysed FXI activation and to determine the dependence of this reaction on phospholipid concentration and composition, thrombin exosites and ionic strength. MethodsFXI was incubated with thrombin in the absence and presence of DXS, PolyP or phospholipid vesicles, and FXIa generation was followed using a chromogenic substrate. The role of thrombin exosites was probed using specific aptamers. The ionic strength was varied using either sodium chloride (NaCl) or tetrapropylammonium chloride. ResultsSimilar to DXS and PolyP, phospholipid vesicles with a high percentage of phosphatidic acid or phosphatidylserine enhanced thrombin-catalysed FXI activation by 1–2 orders of magnitude. Moreover, thrombin and FXI bound to negatively charged phospholipids in direct binding assays. Both thrombin exosites contributed to the ability of thrombin to bind to phospholipids and activate FXI, with a predominance of exosite II. Decreasing the ionic strength greatly stimulated FXI activation by thrombin, both in the absence and presence of phospholipids. However, at equal ionic strength, the reaction was more efficient with NaCl than with tetrapropylammonium chloride, suggesting a specific stimulatory effect of Na+. ConclusionsNegatively charged phospholipids, just as DXS and PolyP, stimulate FXI activation by thrombin via a ‘template mechanism’.