Sphingomyelin Content Research Articles

Sphingolipids in Non-Alcoholic Fatty Liver Disease and Hepatocellular Carcinoma: Ceramide Turnover.

Non-alcoholic fatty liver disease (NAFLD) has emerged as one of the main causes of chronic liver disease worldwide. NAFLD comprises a group of conditions characterized by the accumulation of hepatic lipids that can eventually lead to non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma (HCC), the fifth most common cancer type with a poor survival rate. In this context, several works have pointed out perturbations in lipid metabolism and, particularly, changes in bioactive sphingolipids, as a hallmark of NAFLD and derived HCC. In the present work, we have reviewed existing literature about sphingolipids and the development of NAFLD and NAFLD-derived HCC. During metabolic syndrome, considered a risk factor for steatosis development, an increase in ceramide and sphigosine-1-phosphate (S1P) have been reported. Likewise, other reports have highlighted that increased sphingomyelin and ceramide content is observed during steatosis and NASH. Ceramide also plays a role in liver fibrosis and cirrhosis, acting synergistically with S1P. Finally, during HCC, metabolic fluxes are redirected to reduce cellular ceramide levels whilst increasing S1P to support tumor growth.

Effect of cytomegalovirus infection on the content of myristic acid and sphingomyelin in the blood of the umbilical cord of newborns

Effect of cytomegalovirus infection on the content of myristic acid and sphingomyelin in the blood of the umbilical cord of newborns

Alterations in Sphingomyelin Metabolism Influences Tissue Factor Procoagulant Activity and the Release of TF-Positive Microvesicles

Tissue factor (TF), an integral membrane glycoprotein, is a cofactor for coagulation factor VIIa (FVIIa) and primary cellular initiator of the coagulation. Upon vascular injury or in disease conditions, blood comes in contact with TF, and the formation of TF-FVIIa complex initiates activation of the coagulation cascade. While TF is critical for the maintenance of hemostasis, aberrant expression of TF activity could lead to thrombotic disorders. Typically, most of TF on cell surfaces exist in a cryptic, coagulant inactive state, and an "activation" step (decryption) is essential for the transformation of cryptic TF to prothrombotic TF. Our recent studies showed that sphingomyelin (SM) in the outer leaflet of the plasma membrane is responsible for maintaining TF in an encrypted state in resting cells. The hydrolysis of SM, by either bacterial sphingomyelinase (bSMase) or acid-sphingomyelinase (ASMase) translocated from lysosomes to the outer leaflet in response to ATP, LPS or cytokine stimulation, increased TF activity on intact cells without altering TF protein levels. SM hydrolysis also led to the release of TF+ microvesicles (MVs). Inhibition of ASMase by functional inhibitors blocked LPS-induced TF procoagulant activity without impairing LPS-induced TF antigen levels in both in vitro and in vivo model systems. SM levels in the plasma membrane are regulated primarily by SM synthesizing enzymes, such as sphingomyelin synthases (SMS) 1 and 2 or SM hydrolyzing enzymes, such as ASMase and neutral SMases (nSMase). Many disease conditions, including diabetes, ischemia/hypoxia, and cancer, alter SM metabolism by altering the activities of the above enzymes. These diseases are also known to have increased thrombotic risk. To investigate the importance of SM metabolism in regulating TF procoagulant activity through TF encryption and decryption, we either overexpressed or silenced the enzymes involved in SM metabolism and determined their effect on TF procoagulant activity on intact cells and the release of TF+ MVs. Human monocyte-derived macrophages (MDMs) or human embilical vein endothelial cells (HUVEC) were chosen as cell model systems. In the first set of experiments, MDMs were transfected with adenovirus encoding SMS1, SMS2, or both to overexpress SMS. Analysis of SM levels in the outer leaflet by confocal microscopy and flow cytometry using SM specific binding protein (lysenin) revealed that overexpression of SMS1 or SMS2 increased SM levels in the outer leaflet. Measurement of TF activity on intact cells showed that overexpression of either SMS1 or SMS2 reduced both basal TF activity and the extent of increased TF activity following ATP or bSMase treatment. Overexpression of SMS1 or SMS2 also decreased the release of TF+ MVs. Overexpression of SMS1 or SMS2 had no significant effect on TF antigen levels. In the next set of experiments, MDMS were transfected with control scrambled RNA (scRNA) or siRNA specific for ASMase, nSMase1, nSMase2, or nSMase3. As expected from our earlier studies, ASMase silencing attenuated both basal and ATP-induced increased TF activity in MDMs. In case of nSMases, the knock-down of nSMase2 or nSMase3, but not nSMase1, reduced basal TF activity as well as ATP-induced TF decryption in MDMs. Analysis of SM levels in the outer leaflet showed that silencing of ASMase, nSMase2, or nSMase3 enhanced the SM content. The knock-down of either ASMase or nSMases did not affect TF antigen levels. In additional studies, HUVECs were transfected with control scRNA or siRNA specific for nSMase1, nSMAse2, or nSMase3. Forty eight hour post-transfection, HUVECs were stimulated with TNFα (10 ng/ml) plus IL-1β (10 ng/ml) for 6 h to induce TF expression. Analysis of cell surface TF activity showed that silencing nSMase2 or nSMase3, but not nSMase1, attenuated TNFα+IL-1β-induced TF procoagulant activity without decreasing TNFα+IL-1β-induced TF antigen levels. Overall, our data support the hypothesis that alterations in SM metabolism regulate TF procoagulant activity through encryption and decryption. Disclosures Rao: Takeda: Research Funding.

Supplementation with the omega-3 long chain polyunsaturated fatty acids: Changes in the concentrations of omega-3 index, fatty acids and molecular phospholipids of people at ultra high risk of developing psychosis

Omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) are necessary for optimum mental health, with recent studies showing low n-3 LCPUFA in people at ultra-high risk (UHR) of developing psychosis. Furthermore, people at UHR of psychosis had increased erythrocyte sphingomyelin (SM) and reduced phosphatidylethanolamine (PE) concentrations as well as 27 erythrocyte phospholipid species that differed when compared to erythrocytes from age matched people not at UHR of psychosis. The aim of this analysis was to evaluate the effect of n-3 supplementation on the different erythrocyte lipid species (including SM and PE concentrations) in people at UHR of psychosis. Participants were randomly assigned to fish oil (containing 840 mg EPA and 560 mg DHA per day) or placebo (paraffin oil) for 6 months. Fasted blood samples were taken at baseline and post intervention. Mass spectrometry was used to analyse the molecular phospholipids and fatty acid composition of erythrocytes for both groups. The n-3 index was significantly increased from 3.0% to 4.12% after 6 months of receiving n-3 capsules. Fish oil capsules increased the phospholipid molecular species containing n-3 LCPUFA, and concomitant decreases in n-6 LCPUFA species. SM species did not show any significant changes in n-3 LCPUFA group however, three SM species (SM 16:0, SM 18:0, SM 18:1) significantly increased after 6 months of supplementation with placebo. N-3 supplementation for 6 months led to higher n-3 incorporation into erythrocytes, at the expense of n-6 PUFA across all phospholipid classes analyzed and may have prevented the increase in SM seen in the placebo group.

Selective extraction of phospholipids from whey protein phospholipid concentrate using supercritical carbon dioxide and ethanol as a co-solvent

In recent years, using dairy phospholipids (PL) as functional ingredients has increased because PL have nutritional benefits and functional properties. In this study, a novel 2-step supercritical fluid extraction (SFE) process was used to extract whey protein phospholipid concentrate (WPPC), a dairy co-product obtained during the manufacture of whey protein isolate, for PL enrichment. In the first step, nonpolar lipids in WPPC were removed using neat supercritical carbon dioxide (S-CO2) at 41.4 MPa and 60°C. In the second stage, the feasibility of using the polar solvent ethanol as a co-solvent to increase the solubility of S-CO2 extraction solvent was explored. A 3 × 3 × 2 factorial design with extraction pressure (35.0, 41.4, and 55.0 MPa), temperature (40 and 60°C), and concentration of ethanol (10, 15, and 20%) as independent factors was used to evaluate the extraction efficiency providing the most total PL, and the best proportion of each individual PL from the spent solids collected during S-CO2 SFE. All lipid fractions were analyzed using thin-layer chromatography and high-performance lipid chromatography. The total amount of PL extracted from WPPC was significantly affected by ethanol concentration; the extraction pressure and temperature were nonsignificant. The optimal SFE condition for generating a concentrated PL lipid fraction was 35.0 MPa, 40°C, and 15% ethanol concentration; the highest amount of extracted PL averaged 26.26 g/100 g of fat. Moreover, adjusting SFE condition allowed successful recovery of a high concentration of sphingomyelin, phosphatidylcholine, and phosphatidylethanolamine, giving averages of 11.07, 10.07, and 7.2 g/100 g of fat, respectively, 2 to 3 times more than conventional solvent extraction. In addition, exhausted solids obtained after the SFE process were enriched with denatured proteins (72% on dry basis) with significantly more water-holding capacity and emulsifying capacity than untreated WPPC. Overall, this 2-stage SFE process using neat S-CO2 and ethanol has the greatest potential to produce a PL-rich lipid fraction from WPPC.

The Effect of Nanosized Silicon Molybdate Anions on the Plasma Membrane of Human Fetal Fibroblasts

We used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to study changes in the composition of the plasma membranes of human fetal fibroblasts under the action of nanosized anions of silicon molybdic acid. The dependences of the mass spectra of the main lipids of the plasma membranes on the silicon molybdate concentration were measured and interpreted; the dependences correlate with the layer-by-layer distributions and with the affinity of cholesterol for phospholipids. A new effect for cell biochemistry was discovered, that is, a significant decrease in the relative concentrations of cholesterol and sphingomyelin in plasma membranes under the effect of multiply charged heteropoly anions (HPAs). In aqueous silicon molybdate solutions with a concentration of c ≈ 10 µM/L and an exposure time of 48 h, the amount of cholesterol in plasma membranes decreased by 2–2.5 times, while the amount of sphingomyelin decreased by 20–25%. A new mechanism is proposed for the initial effect of HPA on plasma membranes, which consists of selective etching by multiply charged anions. According to the proposed mechanism, cholesterol and sphingomyelin, the main regulators of permeability and microviscosity of plasma membranes, are extracted from the plasma membrane at the first stage of the interaction of the polyoxometallate anion with the cell. As a consequence of the increased permeability of the plasma membranes in cells, acceleration of vital transmembrane and lateral processes may occur.

The emerging role of the mitochondrial fatty-acid synthase (mtFASII) in the regulation of energy metabolism

Malonyl-CoA synthetase (ACSF3) catalyzes the first step of the mitochondrial fatty acid biosynthesis (mtFASII). Mutations in ACSF3 cause CMAMMA a rare inborn error of metabolism. The clinical phenotype is very heterogeneous, with some patients presenting with neurologic manifestations. In some children, presenting symptoms such as coma, ketoacidosis and hypoglycemia are suggestive of an intermediary metabolic disorder. The overall pathophysiological mechanisms are not understood.In order to study the role of mtFASII in the regulation of energy metabolism we performed a comprehensive metabolic phenotyping with Seahorse technology proteomics in fibroblasts from healthy controls and ACSF3 patients. SILAC-based proteomics and lipidomic analysis were performed to investigate the effects of hypofunctional mtFASII on proteome and lipid homeostasis of complex lipids.Our data clearly confirmed an impaired mitochondrial flexibility characterized by reduced mitochondrial respiration and glycolytic flux due to a lower lipoylation degree. These findings were accompanied by the adaptational upregulation of β-oxidation and by the reduction of anaplerotic amino acids as compensatory mechanism to address the required energy need. Finally, lipidomic analysis demonstrated that the content of the bioactive lipids sphingomyelins and cardiolipins was strongly increased.Our data clearly demonstrate the role of mtFASII in metabolic regulation. Moreover, we show that mtFASII acts as mediator in the lipid-mediated signaling processes in the regulation of energy homeostasis and metabolic flexibility.

Sheep milk components: Focus on nutritional advantages and biofunctional potential

The purpose of the present review is to highlight specific features of the components of sheep milk and dairy products with nutritional and biological significance. Fatty acid profile, milk fat globule size, high CLA, sphingomyelin and fat-soluble vitamins contents are more advantageous in nutritional terms, compared to cow milk. Apart from the high protein content and the several related types of biofunctionality, the non-protein fraction of sheep milk is also significant. In this respect, findings on bioactive peptides, proteose-peptone fraction, nucleoside/nucleotide and polyamine contents are reviewed. Finally, minerals and minor compounds such as oligosaccharides and water-soluble vitamins are presented. It is concluded that sheep milk and dairy products are excellent food matrices, while a great part of beneficial sheep milk components is transferred to by-products.

Predicting respiratory distress syndrome at birth using fast test based on spectroscopy of gastric aspirates. 1. Biochemical part.

To develop a fast bedside lung maturity test. Gastric aspirates obtained from premature infants contain lamellar bodies, carrying lung surfactant. To estimate lung maturity, we isolated lamellar bodies from fresh gastric aspirates by centrifugation. Erythrocytes and other cells were lysed by adding water and discarded subsequently with the supernatant. Mid-infrared spectroscopy was then performed to measure the lung maturity as lecithin-sphingomyelin ratio. Lecithin was determined as dipalmitoylphosphatidylcholine, the most surface-active phospholipid. Algorithms to measure lecithin and sphingomyelin concentrations in fresh gastric aspirates were developed on aspirates from 140 premature infants. Each gastric aspirate sample was divided into two samples: one for mass spectrometry as reference and one for spectroscopy. Development of the algorithm is described in detail in AppendixS1. Gastric aspirates stored at 4-5°C avoid flocculation of proteins and phospholipids in contrast to when the aspirates were frozen and thawed. Omission of freezing and concentration of the lung surfactant by centrifugation combined with diminished influence of proteins improves the spectroscopic measurement of lecithin-sphingomyelin ratio. Measurement of lecithin-sphingomyelin ratio by the new method was performed within 10-15minutes. We present a new fast bedside lung maturity test on fresh gastric aspirate for early targeted surfactant treatment.

Comparison of erythrocyte omega-3 index, fatty acids and molecular phospholipid species in people at ultra-high risk of developing psychosis and healthy people

People classified as ultra-high risk (UHR) of developing psychosis have reduced cellular membrane omega-3 and omega-6 polyunsaturated fatty acids (PUFA). We aimed to compare omega-3 index, fatty acids and molecular phospholipid species from erythrocytes of people with UHR (n = 285) with age-matched healthy controls (n = 120) assessed by mass spectrometry. Lower proportions of PUFA were observed in the UHR group compared to healthy controls; specifically, eicosapentaenoic acid (EPA) was 29.3% lower, docosahexaenoic acid (DHA) was 27.2% lower, arachidonic acid (AA) was 15.8% lower and the omega-3 index was 26.9% lower. The AA to EPA ratio was higher in the UHR group compared to the healthy group. Smoking status had no significant effect on PUFA levels in healthy or the UHR groups. BMI was associated with PUFA levels in the UHR group only and the statistical model only explains 2% of the variance of the PUFA levels. The proportion of nervonic acid was 64.4% higher in the UHR group compared to healthy controls. At a lipid class level, the UHR group had 16% higher concentrations of sphingomyelin (SM) and 46% lower concentrations phosphatidylethanolamine (PE) compared to healthy group. Of the 49 individual molecular phospholipids, twenty-seven phospholipid species were lower in the UHR group. In conclusion, there are clear differences in the proportions of erythrocyte fatty acids and phospholipids between UHR and healthy controls and UHR had higher concentrations of SM and lower concentrations of PE. These differences may represent a promising prodromal risk biomarker in the UHR population to aid clinical diagnosis.

Studies of the Membrane-Protecting Potential of the Combination of 2-Ethyl-6-Methyl-Hydroxypyridine Succinate and Citicoline

Objectives. To assess changes in the phospholipid composition of blood plasma in patients with chronic cerebrovascular disease using the neuroprotectors 2-ethyl-6-methyl-3-hydroxypyridine succinate (Neurox) and citocoline (Neipilept), which are natural metabolites and participants in metabolic processes in the body, alone and in combination. Materials and methods. A total of 40 patients (18 men, 22 women) aged 54–72 years took part in the study; patients had chronic cerebrovascular disease in exacerbation on the background of hypertensive crisis and/or impairments to cardiac rhythm. Results. Extraction of lipids from patients’ blood cells revealed significant reductions in the quantities of all (total) lipids after completion of treatment in patients receiving Neurox, Neipilept, and complex treatment using both agents. Studies of the quantitative composition of blood cell phospholipids showed that there were no significant changes in patients taking Neurox, while citicoline, alone and in combination with 2-ethyl-6-methyl-3-hydroxypyridine succinate, led to increases in total quantities. Assessment of the qualitative composition of classes of phospholipids in plasma showed no significant changes in patients taking Neurox, while those receiving Neipilept alone and with 2-ethyl-6-methyl-3-hydroxypyridine succinate showed significant increases in plasma phosphatidylcholine. There were no significant changes in phosphatidylinositol, phosphatidylserine, or sphingomyelin contents.

Very Low Crude Protein and Varying Glycine Concentrations in the Diet Affect Growth Performance, Characteristics of Nitrogen Excretion, and the Blood Metabolome of Broiler Chickens

The minimum to which dietary crude protein (CP) level for broiler chickens can be reduced without decreasing growth and the glycine equivalent (Glyequi) concentration required are not known. The plasma metabolome might reflect dietary influences on physiological processes. The aim of this study was to investigate the effect of 3 low CP levels with 4 Glyequi concentrations on growth and characteristics of nitrogen excretion, and to identify plasma metabolome variations. Male Ross308 broiler chickens were provided 1 of 12 dietary treatments in 84 metabolism cages (10/cage) from days 7 to 21. Three diets with 163 (CP163), 147 (CP147), and 132 (CP132) g CP/kg were formulated, each containing 12, 15, 18, and 21 g Glyequi/kg. Essential amino acid concentrations were the same in all diets. Animals and feed were weighed on days 7 and 21 to determine average daily gain (ADG) and gain:feed ratio (G:F). Excreta were collected from days 18 to 21 to analyze nitrogenous components, and blood was obtained on day 21 to conduct a metabolome analysis. Two-factor ANOVA showed significant interaction effects for ADG, G:F, and nitrogen efficiency (P<0.001). Reduction of CP decreased ADG and G:F, and increased nitrogen efficiency. Glyequi supplementation increased ADG (by 7.9 g/d) and G:F (by 0.07 g/g) at CP132. The ADG (by 2.4 g/d) at CP147 and G:F (by 0.02 g/g) at CP147 and CP163 increased up to 15 g Glyequi/kg. Multivariate statistical analysis showed an influence of Glyequi on plasma acylcarnitine and lysophosphatidylcholine concentrations, and a decrease of plasma phosphatidylcholine and sphingomyelin concentrations with reduced CP. These results suggest that a nutrient other than Glyequi limited growth when CP was reduced from CP163 to CP147, and that the response of broiler chickens to Glyequi is dependent on the dietary CP level. Plasma metabolites indicate dietary influences on the physiological state of the animals.

Metabolic Disturbances Identified in Plasma Samples from ST-Segment Elevation Myocardial Infarction Patients.

ST-segment elevation myocardial infarction (STEMI) is the most severe form of myocardial infarction (MI) and the main contributor to morbidity and mortality caused by MI worldwide. Frequently, STEMI is caused by complete and persistent occlusion of a coronary artery by a blood clot, which promotes heart damage. STEMI impairment triggers changes in gene transcription, protein expression, and metabolite concentrations, which grants a biosignature to the heart dysfunction. There is a major interest in identifying novel biomarkers that could improve the diagnosis of STEMI. In this study, the phenotypic characterization of STEMI patients (n = 15) and healthy individuals (n = 19) was performed, using a target metabolomics approach. Plasma samples were analyzed by UPLC-MS/MS (ultra-high-performance liquid chromatography-tandem mass spectrometry) and FIA-MS (MS-based flow injection analysis). The goal was to identify novel plasma biomarkers and metabolic signatures underlying STEMI. Concentrations of phosphatidylcholines, lysophosphatidylcholines, sphingomyelins, and biogenic amines were altered in STEMI patients in relation to healthy subjects. Also, after multivariate analysis, it was possible to identify alterations in the glycerophospholipids, alpha-linolenic acid, and sphingolipid metabolisms in STEMI patients.

Cholinergic nervous system and glaucoma: From basic science to clinical applications.

The cholinergic system has a crucial role to play in visual function. Although cholinergic drugs have been a focus of attention as glaucoma medications for reducing eye pressure, little is known about the potential modality for neuronal survival and/or enhancement in visual impairments. Citicoline, a naturally occurring compound and FDA approved dietary supplement, is a nootropic agent that is recently demonstrated to be effective in ameliorating ischemic stroke, traumatic brain injury, Parkinson's disease, Alzheimer's disease, cerebrovascular diseases, memory disorders and attention-deficit/hyperactivity disorder in both humans and animal models. The mechanisms of its action appear to be multifarious including (i) preservation of cardiolipin, sphingomyelin, and arachidonic acid contents of phosphatidylcholine and phosphatidylethanolamine, (ii) restoration of phosphatidylcholine, (iii) stimulation of glutathione synthesis, (iv) lowering glutamate concentrations and preventing glutamate excitotoxicity, (v) rescuing mitochondrial function thereby preventing oxidative damage and onset of neuronal apoptosis, (vi) synthesis of myelin leading to improvement in neuronal membrane integrity, (vii) improving acetylcholine synthesis and thereby reducing the effects of mental stress and (viii) preventing endothelial dysfunction. Such effects have vouched for citicoline as a neuroprotective, neurorestorative and neuroregenerative agent. Retinal ganglion cells are neurons with long myelinated axons which provide a strong rationale for citicoline use in visual pathway disorders. Since glaucoma is a form of neurodegeneration involving retinal ganglion cells, citicoline may help ameliorate glaucomatous damages in multiple facets. Additionally, trans-synaptic degeneration has been identified in humans and experimental models of glaucoma suggesting the cholinergic system as a new brain target for glaucoma management and therapy.

609-P: Effect of Rosuvastatin on Lipoprotein Sphingolipids in Patients with Type 2 Diabetes

Statin therapy reduces cardiovascular risk in type 2 diabetes (T2DM), partly by improving dyslipidemia, and partly through ‘pleiotropic’ effects. Sphingolipids, including ceramides, are amphiphilic components of lipoprotein surface monolayers. Sphingolipids regulate lipoprotein surface fluidity, and include key signaling molecules: ceramides are specifically associated with apoptosis and risk for premature coronary heart disease. Effects of statins on the sphingolipid content of lipoproteins are poorly defined. Using liquid chromatography/electrospray ionization-tandem mass spectrometry, we determined fasting plasma concentrations of individual ceramides (Cer), sphingomyelins (SM), and glycosphingolipids (hexosyl- and lactosyl-Cer) in plasma from 19 men and 21 women with T2DM, before and after treatment with rosuvastatin (10 mg/day, 6 weeks). Exclusion criteria were use of ‘statins’ in the preceding 6 months, and any current use of lipid-modifying agents. Using existing lipoprotein compositional data, we calculated effects of rosuvastatin therapy on non-HDL sphingolipid content. Results: Rosuvastatin reduced total cholesterol (C) (by 33%), triglycerides (20%), LDL-C (49%), and non-HDL particle number (34%); HDL-C was unaffected. It decreased total SM (15%), Cer (29%), and hexosyl- (30%) and lactosyl- (34%) Cer, independent of gender. Assuming HDL composition was unaffected, rosuvastatin reduced non-HDL SM by 42% and Cer by 61%: these reductions remained significant after correction for non-HDL-C and/or non-HDL lipoprotein surface area. Conclusions: In T2DM, rosuvastatin lowers not only the number of non-HDL particles, but also the sphingolipid, and especially the Cer, content of each particle. This effect is independent of gender, potentially anti-atherogenic, and may represent a new pleiotropic effect of statins. Further studies are needed to confirm these findings in isolated lipoprotein classes, and to determine mechanism(s). Disclosure C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. A. Gosmanova: None. M.J. Leyva: None. C.E. Aston: None. T. Lyons: None.

Maternal Choline Supplementation During Gestational Diabetes Causes Long-Term Phenotypic Changes in Offspring (P11-132-19)

ObjectivesUsing a mouse gestational diabetes mellitus (GDM) model, this study investigated whether maternal choline supplementation (MCS) could alter postnatal growth and metabolic abnormalities associated with GDM. MethodsC57BL/6 mice were either fed a low fat (LF, 10kcal % fat) control diet or a high fat (HF, 60kcal % fat) diet prior to and during pregnancy to induce GDM. These mice received either 25mM choline (MCS) or plain drinking water, After weaning, offspring were fed the HF diet for 6 weeks before glucose tolerance testing and dissection. ResultsIn male offspring from MCS-GDM mothers, we observed a decrease in fasting blood glucose levels and an increase in glucose tolerance when comparing to other groups (P < 0.05). Liver choline metabolite measurements demonstrated that free choline content was lower (P = 0.01) in the MCS-GDM male offspring than control GDM male offspring; there is also an increase in liver sphingomyelin concentrations (P = 0.007) in female offspring from MCS-GDM compared to control GDM dams. ConclusionsMCS during GDM leads to improvements in blood glucose control in male mouse offspring exposed to a postnatal HF environment. Funding SourcesNIGMS and NIDDK; New York Academy of Sciences.

Role of lipid composition on the structural and mechanical features of axonal membranes: a molecular simulation study

The integrity of cellular membranes is critical for the functionality of axons. Failure of the axonal membranes (plasma membrane and/or myelin sheath) can be the origin of neurological diseases. The two membranes differ in the content of sphingomyelin and galactosylceramide lipids. We investigate the relation between lipid content and bilayer structural-mechanical properties, to better understand the dependency of membrane properties on lipid composition. A sphingomyelin/phospholipid/cholesterol bilayer is used to mimic a plasma membrane and a galactosylceramide/phospholipid/cholesterol bilayer to mimic a myelin sheath. Molecular dynamics simulations are performed at atomistic and coarse-grained levels to characterize the bilayers at equilibrium and under deformation. For comparison, simulations of phospholipid and phospholipid/cholesterol bilayers are also performed. The results clearly show that the bilayer biomechanical and structural features depend on the lipid composition, independent of the molecular models. Both galactosylceramide or sphingomyelin lipids increase the order of aliphatic tails and resistance to water penetration. Having 30% galactosylceramide increases the bilayers stiffness. Galactosylceramide lipids pack together via sugar-sugar interactions and hydrogen-bond phosphocholine with a correlated increase of bilayer thickness. Our findings provide a molecular insight on role of lipid content in natural membranes.

Correction of Cold Damage to Mammalian Erythrocytes by Chlorpromazine to Influence the Dynamic Structure of a Membrane

Abstract—The resistance of mammalian erythrocytes (human, dog, horse, bull, and rabbit) to cold shock in the presence of chlorpromazine was studied; its effect on the state of erythrocyte membranes was investigated. The bond strength between membrane phospholipids of mammalian erythrocytes and the characteristics of the cold shock of these cells was determined with the correlation analysis. It has been established that erythrocytes of mammals whose membranes contain a high content of sphingomyelin and phosphatidylethanolamine and a low content of phosphatidylcholines are more resistant to cold shock. Chlorpromazine showed high efficiency in protecting mammalian erythrocytes against cold shock. The dynamic structure of membranes of human erythrocytes treated with the chlorpromazine was studied by EPR of spin-probes. The use of a set of spin-labeled probes: palmitic acid amide, 5-DOXYL stearic acid, and 16-DOXYL stearic acid, which allow studying the micro-viscosity parameters of the lipid bilayer of erythrocyte membranes in the transmembrane direction, made it possible to establish the locations of chlorpromazine action, namely, in the region of polar heads and hydrophobic tails of membrane phospholipids.

Valine increases milk fat synthesis in mammary gland of gilts through stimulating AKT/MTOR/SREBP1 pathway†.

Lactating mammary glands are among the most active lipogenic organs and provide a large percentage of bioactive lipids and calories for infant growth. The branched-chain amino acid (BCAA) valine is known to modulate fatty acids synthesis in adipose tissue; however, its effects on fat metabolism and the underlying mechanisms in mammary glands remain to be determined. Valine supplementation during late pregnancy significantly increased the contents of total milk fat, triglyceride, sphingomyelin, and polyunsaturated fatty acids in the colostrum of gilts. Further study in porcine mammary epithelial cells (PMECs) confirmed that valine upregulated the phosphorylation levels of AKT-activated MTOR and subsequently induced the nuclear accumulation of sterol regulatory element binding protein 1 (SREBP1), thus increasing the expression of proteins related to fatty acids synthesis and intracellular triacylglycerol content. Inhibition of AKT/MTOR signaling or silencing of SREBP1 in PMECs downregulates the expression of proteins related to fatty acids synthesis and intracellular triacylglycerol content. Our findings indicated that valine enhanced milk fat synthesis of colostrum in porcine mammary glands via the AKT/MTOR/SREBP1 signaling pathway.

Homogeneous and Heterogeneous Bilayers of Ternary Lipid Compositions Containing Equimolar Ceramide and Cholesterol.

Cell membranes have been proposed to be laterally inhomogeneous, particularly in the case of mammalian cells, due to the presence of "domains" enriched in sphingolipids and cholesterol (Chol). Among membrane sphingolipids, sphingomyelin (SM) in the cell plasma membrane is known to be degraded to ceramide (Cer) by acid sphingomyelinases under stress conditions. Since cholesterol (Chol) is abundant in the plasma membrane, the study of ternary mixtures SM:Chol:Cer is interesting from the point of view of membrane biophysics, and it might be physiologically relevant. In previous studies, we have described the homogeneous gel phase formed by phospholipid:Chol:Cer at 54:23:23 mol ratios, where phospholipid was either SM or dipalmitoylphosphatidylcholine (DPPC). We now provide new data, based on trans-parinaric acid and diphenylhexatriene fluorescence, supporting that the gel phase includes all three components in a single bilayer. The main question addressed in this paper is the stability of the ternary gel phase when bilayer composition is changed, specifically when the SM proportion is varied. To this aim, we have prepared bilayers of composition phospholipid:Chol:Cer at X:Y:Y ratios, in which phospholipid increased between 54 and 70 mol %. The N-palmitoyl derivatives of SM (pSM) and Cer (pCer) have been used. We observe that for X = 54 or 60 mol %, a gel phase is clearly predominant. However, when the proportion of phospholipid increases beyond 60 mol %, i.e., in 66:17:17 or 70:15:15 mixtures, a lateral phase separation occurs at the micrometer scale. These data can be interpreted in terms of a pCer:Chol interaction, that would predominate at the lower phospholipid concentrations. The putative pCer:Chol complexes (or nanodomains) would mix well with the phospholipid. At the higher SM concentrations pSM:pCer and pSM:Chol interactions would become more important, giving rise to the coexisting gel and liquid-ordered phases respectively. Heterogeneity, or lateral phase separation, occurs more easily with pSM than with DPPC, indicating a higher affinity of SM over DPPC for Chol or Cer. The observation that heterogeneity, or lateral phase separation, occurs more easily with pSM than with DPPC, indicates a higher affinity of SM over DPPC for Chol or Cer, and can be related to cell regulation through the sphingolipid signaling pathway.