Oleate Oxidation Research Articles

Kinetics of the Catalytic Oxidation of Methyl Oleate

Kinetics of the Catalytic Oxidation of Methyl Oleate

Lower Metabolic Potential and Impaired Metabolic Flexibility in Human Lymph Node Stromal Cells from Patients with Rheumatoid Arthritis.

Cellular metabolism is important for determining cell function and shaping immune responses. Studies have shown a crucial role for stromal cells in steering proper immune responses in the lymph node microenvironment. These lymph node stromal cells (LNSCs) tightly regulate immune tolerance. We hypothesize that malfunctioning LNSCs create a microenvironment in which normal immune responses are not properly controlled, possibly leading to the development of autoimmune diseases such as rheumatoid arthritis (RA). Therefore, we set out to determine their metabolic profile during health and systemic autoimmunity. We included autoantibody positive individuals at risk of developing RA (RA-risk individuals), RA patients and healthy volunteers. All study subjects underwent lymph node biopsy sampling. Mitochondrial function in cultured LNSCs was assessed by quantitative PCR, flow cytometry, Seahorse and oleate oxidation assays. Overall, mitochondrial respiration was lower in RA(-risk) LNSCs compared with healthy LNSCs, while metabolic potential was only lower in RA LNSCs. To maintain basal mitochondrial respiration, all LNSCs were mostly dependent on fatty acid oxidation. However, RA(-risk) LNSCs were also dependent on glutamine oxidation. Finally, we showed that RA LNSCs have impaired metabolic flexibility. Our results show that the metabolic landscape of LNSCs is not only altered during established disease, but partly already in individuals at risk of developing RA. Future studies are needed to investigate the impact of restoring metabolic capacity in LNSC-mediated immunomodulation and disease progression.

Effect of Pendant Sulfide and Sulfonyl Groups on the Thermal, Flow, and Antioxidative Properties of Lipid-Based Aliphatic Monoesters

Thermal, flow, and oxidative stability behavior of oleyl oleate monoesters derivatized with sulfur-containing functional groups (sulfide and sulfonyl) suggests that these compounds may be suitable candidates as sustainable alternative base oils to replace mineral oils in lubricant formulations. A robust thiol-ene addition and oxidation synthesis route was utilized to prepare the materials in high yields and high purity with no byproducts. Changes in the functional properties of oleyl oleate are attributable to the enhanced intermolecular forces and irregular conformations introduced by the bulky polar sulfur-containing groups, which introduce steric hindrances and alter phase behavior. The derivatization of oleyl oleate with sulfide and sulfonyl pendant groups resulted in a lower enthalpy of crystallization (10 kJ/mol compared to 76 kJ/mol for oleyl oleate) and an increased viscosity from 16.3 mPa·s to as high as 175.5 mPa·s at 40 °C. The sulfonyl pendant groups imparted higher viscosity to oleyl oleate due to sulfonyl–sulfonyl interactions. The presence of sulfonyl and sulfide pendant groups increased oleyl oleate oxidation onset (Tonox) by 47 and 149 °C, respectively. The sulfide pendant groups converted hydroperoxides as they are formed into non-radical derivatives and thus delayed oxidation. Overall, the sulfide- and sulfonyl-branched oleyl oleate monoesters of this work presented useful thermal transition and viscosity profiles which are competitive with those of mineral oils, making them suitable alternatives for use in lubricant formulations.

Altered lipid metabolism in synovial fibroblasts of individuals at risk of developing rheumatoid arthritis

ObjectiveFibroblast-like synoviocytes (FLS) can augment the inflammatory process observed in synovium of patients with rheumatoid arthritis (RA). A recent transcriptomic study in synovial biopsies revealed changes in metabolic pathways before disease onset in absence of synovial tissue inflammation. This raises the question whether alterations in cellular metabolism in tissue resident FLS underlie disease pathogenesis. Materials and methodsTo study this, we compared the metabolic profile of FLS isolated from synovial biopsies from individuals with arthralgia who were autoantibody positive but without any evidence of arthritis (RA-risk individuals, n = 6) with FLS from patients with RA (n = 6), osteoarthritis (OA, n = 6) and seronegative controls (n = 6). After synovial digestion, FLS were cultured in vitro and cellular metabolism was assessed using quantitative PCR, flow cytometry, XFe96 Seahorse Analyzer and tritium-labelled oleate oxidation assays. ResultsReal-time metabolic profiling revealed that basal (p < 0.0001) and maximum mitochondrial respiration (p = 0.0024) were significantly lower in RA FLS compared with control FLS. In all donors, basal respiration was largely dependent on fatty acid oxidation while glucose was only highly used by FLS from RA patients. Moreover, we showed that RA-risk and RA FLS are less metabolically flexible. Strikingly, mitochondrial fatty acid β-oxidation was significantly impaired in RA-risk (p = 0.001) and RA FLS (p < 0.0001) compared with control FLS. ConclusionOverall, this study showed several metabolic alterations in FLS even in absence of synovial inflammation, suggesting that these alterations already start before clinical manifestation of disease and may drive disease pathogenesis.

Chemical Indices and Kinetic Evaluation of β-Sitosteryl Oleate Oxidation in a Model System of Bulk Oil.

Concerns have been raised about the safety and tolerability of phytosterol esters due to their vulnerability to oxidation. Herein, oxidation of the unsaturated fatty acid-phytosterol ester, namely β-sitosteryl oleate, was observed in comparison to native β-sitosterol after accelerated storage at 65 °C for 35 days in a bulk oil model system. Depending on the sterol structure, various chemical indices of lipid oxidation, including hydroperoxide value (HPV), thiobarbituric acid reactive substances (TBARS), p-anisidine value (AnV), and 7-keto derivatives, changed at varying rates in both samples. Such indicators for β-sitosteryl oleate appeared to be obtained at higher concentrations than those for β-sitosterol. The first order kinetic was used to describe the losses of β-sitosteryl oleate and β-sitosterol in bulk oil. It was discovered that the β-sitosteryl oleate (k = 0.0202 day-1) underwent oxidative alteration more rapidly than β-sitosterol (k = 0.0099 day-1). Results indicated that physical structure was the principal factor in the determination of storage stability of phytosterol and its ester. Research on antioxidants and storage techniques can be expanded in order to reduce the oxidative loss of phytosterol esters during storage and improve the safety and tolerability of phytosterol esters.

Essential lipid autacoids rewire mitochondrial energy efficiency in metabolic dysfunction-associated fatty liver disease.

Injury to hepatocyte mitochondria is common in metabolic dysfunction-associated fatty liver disease. Here, we investigated whether changes in the content of essential fatty acid-derived lipid autacoids affect hepatocyte mitochondrial bioenergetics and metabolic efficiency. The study was performed in transgenic mice for the fat-1 gene, which allows the endogenous replacement of the membrane omega-6-polyunsaturated fatty acid (PUFA) composition by omega-3-PUFA. Transmission electron microscopy revealed that hepatocyte mitochondria of fat-1 mice had more abundant intact cristae and higher mitochondrial aspect ratio. Fat-1 mice had increased expression of oxidative phosphorylation complexes I and II and translocases of both inner (translocase of inner mitochondrial membrane 44) and outer (translocase of the outer membrane 20) mitochondrial membranes. Fat-1 mice also showed increased mitofusin-2 and reduced dynamin-like protein 1 phosphorylation, which mediate mitochondrial fusion and fission, respectively. Mitochondria of fat-1 mice exhibited enhanced oxygen consumption rate, fatty acid β-oxidation, and energy substrate utilization as determined by high-resolution respirometry, [1- 14 C]-oleate oxidation and nicotinamide adenine dinucleotide hydride/dihydroflavine-adenine dinucleotide production, respectively. Untargeted lipidomics identified a rich hepatic omega-3-PUFA composition and a specific docosahexaenoic acid (DHA)-enriched lipid fingerprint in fat-1 mice. Targeted lipidomics uncovered a higher content of DHA-derived lipid autacoids, namely resolvin D1 and maresin 1, which rescued hepatocytes from TNFα-induced mitochondrial dysfunction, and unblocked the tricarboxylic acid cycle flux and metabolic utilization of long-chain acyl-carnitines, amino acids, and carbohydrates. Importantly, fat-1 mice were protected against mitochondrial injury induced by obesogenic and fibrogenic insults. Our data uncover the importance of a lipid membrane composition rich in DHA and its lipid autacoid derivatives to have optimal hepatic mitochondrial and metabolic efficiency.

Study on the mechanism of auto-oxidation of Jatropha biodiesel and the oxidative cleavage of C[sbnd]C bond

Jatropha biodiesel was obtained according to the continuous preparation process which included vapor esterification - transesterification - methanol steam distillation. Accelerated oxidation of small Jatropha biodiesel was obtained by the Rancimat method. GC–MS and liquid phase micro-extraction were used to study and analyze the components in the oxidation process of Jatropha curcas biodiesel. The electronic effects of the related reactants and products were calculated by density functional theory, followed by the deduction of the related chemical reaction paths. Experimental investigation shows that methyl linoleate is the main factor affecting the oxidation stability of the Jatropha biodiesel. The main volatile products at the initial stages of the oxidation of methyl linoleate are hexanal, methyl octanoate, styrene, and 2-heptenal. The cis/trans-3-octyl-oxiranyl octanoic acid methyl ester (18.03% yield) is produced by the reaction of peroxy acid and methyl oleate during the oxidation of methyl oleate. The hydrogen extraction reaction is difficult to occur, and the oxidation reaction energy barrier is relatively high due to the relatively large bond energy of the CH bond in the methyl stearate molecule. In this manuscript, the auto-oxidation mechanism of the biodiesel fatty acid methyl esters at the initial stage of oxidation, the path of oxidative cleavage of the CC bond of Jatropha biodiesel and the formation process of ethylene oxide structure are obtained through DFT calculation and analysis of the oxidation products.

Rate Constants of the Interaction of 2-Thio-6-Aminouracil with Peroxyl Radicals

It was shown that 2-thio-6-aminouracil (TAU) is an inhibitor of the radical-chain oxidation of ethylbenzene and methyl oleate. The reactivity of structurally different peroxyl radicals toward TAU was compared. The rate constants of these reactions decreased in the order 1,4-dioxane peroxyl radical, ethylbenzene peroxyl radical, and methyl oleate peroxyl radical (k7 × 104 = 30, 5.2, and 2.0 L mol–1 s–1, respectively, at 333 K). The reason for the decrease in the reactivity of ethylbenzene and methyl oleate peroxyl radicals was suggested.

Tungsten Peroxopolyoxo Complexes as Advanced Catalysts for the Oxidation of Organic Compounds with Hydrogen Peroxide

Selective oxidation of organic substrates by environment-friendly oxidizing agents is an important ingredient of the sustainable chemical industry. Here we report a comprehensive study in the field of metal peoroxocomplex catalysis for the selective liquid phase oxidation of various organic substrates. A number of well-defined bi-functional tungsten complex catalysts with tetra nuclear structure {PO4[WO(O2)2]4}3- in combination with a phase-transfer agents were synthesized. The structural properties were thoroughly studied using of IR, Raman and EXAFS spectroscopy. By combining different spectroscopy techniques were able to elucidate the effect of quaternary ammonium cations on the structural properties of the resulting peroxo complexes. The catalytic properties of these well-defined material were then evaluated in bi-phasic selective oxidation of cyclooctene, methyl oleate and N-phosphonomethyliminodiacetic acid with hydrogen peroxide under mild conditions. For every substrate we were able to achieve high conversion at the selectivity towards a target product close to 100%.

Effects of Temperature, Antioxidants, and High‐Vacuum Distillation on the Oxidation of Biodiesel Derived from Waste Vegetable Oil

AbstractBiodiesel offers several environmental benefits and improvements to some fuel performance properties, but its poor oxidative stability has been a major concern. Currently, the accepted practice to improve biodiesel oxidative stability is the addition of antioxidants; numerous antioxidants have been studied but their effectiveness in inhibiting biodiesel oxidation is difficult to predict due to variation with resonance stability, solubility, reactivity, and volatility. To improve prediction efforts, this study explored the Rapid Small‐Scale Oxidation Test (RSSOT) as a means to investigate how biodiesel oxidation is affected by antioxidant concentration and temperature, and compared its results with the oxidative stability index test. A weak correlation was identified due to antioxidant variation. A kinetic model expressed in temperature and induction period was developed for biodiesel before high‐vacuum distillation (HVD), after HVD and also after HVD with three concentrations of propyl gallate (PG) and tert‐butylhydroquinone (TBHQ) antioxidants. The approach was validated by comparing collected data on the oxidation of methyl oleate with kinetic parameters found in the literature. Antioxidant concentrations from 130–930 ppm were tested, and the results revealed that the apparent activation energy of biodiesel oxidation increases with increasing concentration of primary antioxidants and decreases during vacuum distillation. When treated with an increasing concentration (130–930 ppm) of PG and TBHQ, the apparent activation energies of a vacuum distilled biodiesel changed from 108.46 ± 4.45 to 112.72 ± 1.46 kJ·mol−1 and from 77.14 ± 2.25 to 89.91 ± 2.29 kJ·mol−1, respectively. These observed trends agree with both the accepted mechanism of primary oxidation of fuels and mode of action of primary antioxidants.

Regulatory System of Lipid Peroxidation as a Basis for Ecological Testing

Model systems were proposed, using previously obtained experimental data, for investigating the mechanism of regulation of oxidative processes in lipids isolated from natural objects, preparations, and various components of aqueous medium. The models include low-temperature oxidation of methyl oleate in a thin layer as a model system of lipid peroxidation in biological membranes; computer simulation to determine the involvement of lipids and biologically active substances at different stages of autoxidation; and model of spontaneous autoxidation of lecithin in aqueous solution to assess the ability of aqueous medium components to participate in the regulation of oxidative processes in biological systems.

Differential Regulation of Cardiac Substrate Utilization in Response to Chronic Central Nervous System Administration of Leptin and Melanotan II in Rats with Myocardial Infarction

The brain leptin‐melanocortin system pathway plays an important role in regulating many physiological functions including energy homeostasis. We found that chronic intracerebroventricular (ICV) infusion of leptin or the melanocortin 4 receptor (MC4R) agonist Melanotan II, MTII, markedly attenuated cardiac dysfunction in rats with myocardial infarction (MI) induced by permanent left anterior descending coronary artery (LAD) ligation. In the present study we examined if activation of leptin‐MC4R axis in the central nervous system (CNS) alters cardiac substrate utilization in rats with MI. Male Sprague‐Dawley rats at 15 weeks of age were implanted with an ICV cannula into the lateral ventricle. After 10 days of recovery, the LAD was permanently ligated and saline vehicle (0.5 μL/hr, n=5), leptin (15 μg/day, n=5) or MTII (240 ng/day, n=3) was infused ICV via osmotic minipump for 14 consecutive days. On day 14 of treatment the hearts were quickly excised and perfused ex vivo in the working mode with glucose (5.5 mmol/L) and the fatty acid oleate (0.4 mmol/L). After a 5‐min baseline equilibration period the hearts were perfused for an additional 20 min and coronary flow samples were collected every 5 min to determine rates of substrate oxidation by quantitative measurement of [14C]O2 and [3H]2O using [U‐14C]glucose (0.08 μCi/ml) and [9,10‐3H]oleate (0.1 μCi/ml) as the radiolabeled tracers. Compared to vehicle treatment, chronic ICV leptin infusion for 2 weeks markedly increased glucose oxidation (0.60±0.04 vs. 0.27±0.02 μmol/min/g dry heart weight) without altering oleate oxidation (0.95±0.01 vs. 0.90±0.02 μmol/min/g dry heart weight). Chronic central MTII infusion did not alter glucose oxidation (0.25±0.03 vs. 0.27±0.02 μmol/min/g dry heart weight) but increased fatty acid oxidation compared to vehicle treatment (1.13±0.01 vs. 0.90±0.02 μmol/min/g dry heart weight). These results suggest the CNSmechanisms by which leptin and MC4R activation improve cardiac function post MI may involve increased myocardial bioenergetics by differential modulation of glucose and fatty acid utilization.Support or Funding InformationNHLBI PO1HL51971, NIGMS P20GM104357 and NIGMS U54GM115428This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Proposal for an individualized dietary strategy in patients with very long-chain acyl-CoA dehydrogenase deficiency.

Patients with very long chain acyl-CoA dehydrogenase deficiency (VLCADD), a long chain fatty acid oxidation disorder, are traditionally treated with a long chain triglyceride (LCT) restricted and medium chain triglyceride (MCT) supplemented diet. Introduction of VLCADD in newborn screening (NBS) programs has led to the identification of asymptomatic newborns with VLCADD, who may have a more attenuated phenotype and may not need dietary adjustments. To define dietary strategies for individuals with VLCADD based on the predicted phenotype. We evaluated long-term dietary histories of a cohort of individuals diagnosed with VLCADD identified before the introduction of VLCADD in NBS and their beta-oxidation (LC-FAO) flux score (rate of oleate oxidation) in cultured skin fibroblasts in relation to the clinical outcome. Based on these results a dietary strategy is proposed. Sixteen individuals with VLCADD were included. One had an LC-FAO flux score >90%, was not on a restricted diet and is asymptomatic to date. Four patients had an LC-FAO flux score <10%, and significant VLCADD related symptoms despite the use of strict diets including LCT restriction, MCT supplementation and nocturnal gastric drip feeding. Patients with an LC-FAO flux score between 10 and 90% (n = 11) showed a more heterogeneous phenotype. This study shows that a strict diet cannot prevent poor clinical outcome in severely affected patients and that the LC-FAO flux is a good predictor of clinical outcome in individuals with VLCADD identified before its introduction in NBS. Hereby, we propose an individualized dietary strategy based on the LC-FAO flux score.

The effect of sodium dodecyl sulfate on the rate methyl oleate oxidation in aqueous emulsion

The effect of sodium dodecyl sulfate on the rate methyl oleate oxidation in aqueous emulsion

Proposal for an individualized dietary strategy in patients with very long-chain acyl-CoA dehydrogenase deficiency

Background Patients with very long chain acyl-CoA dehydrogenase deficiency (VLCADD), a long chain fatty acid oxidation disorder, are traditionally treated with a long chain triglyceride (LCT) restricted and medium chain triglyceride (MCT) supplemented diet. Introduction of VLCADD in newborn screening (NBS) programs has led to the identification of asymptomatic newborns with VLCADD, who may have a more attenuated phenotype and may not need dietary adjustments. Objective To define dietary strategies for individuals with VLCADD based on the predicted phenotype. Method We evaluated long-term dietary histories of a cohort of individuals diagnosed with VLCADD identified before the introduction of VLCADD in NBS and their beta-oxidation (LC-FAO) flux score (rate of oleate oxidation) in cultured skin fibroblasts in relation to the clinical outcome. Based on these results a dietary strategy is proposed. Results Sixteen individuals with VLCADD were included. One had an LC-FAO flux score >90%, was not on a restricted diet and is asymptomatic to date. Four patients had an LC-FAO flux score <10%, and significant VLCADD related symptoms despite the use of strict diets including LCT restriction, MCT supplementation and nocturnal gastric drip feeding. Patients with an LC-FAO flux score between 10 and 90% (n = 11) showed a more heterogeneous phenotype. Conclusions This study shows that a strict diet cannot prevent poor clinical outcome in severely affected patients and that the LC-FAO flux is a good predictor of clinical outcome in individuals with VLCADD identified before its introduction in NBS. Hereby, we propose an individualized dietary strategy based on the LC-FAO flux score.

Optimization of the vegetable oil composition in alkyd resins: A kinetic approach based on FAMEs autoxidation

Abstract The autoxidation of FAMEs of colza, sunflower and linseed oils was studied at 40 °C under oxygen atmosphere at 150 kPa and was compared to that of mixtures of pure methyl oleate, linoleate and linolenate. Three steps corresponding to an induction time, an autocatalytic process and a pseudo steady-state could be distinguished and their kinetic constants were calculated for each oil. The influence of methyl linoleate on methyl oleate oxidation was determined at eight different ratios, highlighting that a 35/65 w/w composition corresponding to the sunflower one was a good compromise between oxidation time and minimization of methyl linoleate amount. Same approach was undertaken on this mixture to investigate the influence of methyl linolenate as a third constituent using pure ester and linseed oil FAMEs. A weight fraction of 15–20% was found to be optimal to favor the oxidation. Methyl linolenate has no influence on the relative disappearance of methyl linoleate versus methyl oleate. Hence, the most oxidizable composition with the lowest amount of the tri-unsaturated FAME is the ternary mixture methyl oleate/methyl linoleate/methyl linolenate = 29:53:18 ratio, which corresponds to a mixture of sunflower and linseed oils at a ≈ 60:40 ratio. This would be the best vegetable oil composition for alkyd resins.

Cardiac STAT3 Deficiency Impairs Contractility and Metabolic Homeostasis in Hypertension.

Signal transducer and activator of transcription 3 (STAT3) protects the heart from acute ischemic stress. However, the importance of STAT3 to the heart in chronic stress, such as hypertension, is not known. To study this, we used cardiomyocyte-targeted STAT3 knockout (KO) mice and Angiotensin II (ANG II) infusion by osmotic minipumps. After 4 weeks, ANG II induced similar cardiac hypertrophy in wild type (WT) and cardiac Cre-expressing control (CTRL) mice with no impairment of cardiac function. In contrast, STAT3 KO mice exhibited reduced contractile function but similar hypertrophy to CTRL mice. Ejection fraction and fractional shortening decreased by 22.5 and 27.3%, respectively. Since STAT3 has direct protective effects on mitochondrial function, we examined rates of glucose and oleate oxidation by isolated perfused hearts using a Langendorff system. Hearts of ANG II-treated STAT3 KO and CTRL mice had similar rates of oleate oxidation as saline-infused WT mice. Rates of glucose oxidation were similar between hearts of WT plus saline and CTRL plus ANG II mice; however, glucose oxidation was increased by 66% in hearts of ANG II-treated STAT3 KO mice. The ratio of maximal ATP yield from glucose to fatty acid oxidation was 21.1 ± 3.1 in hearts of ANG II-treated STAT3 KO mice vs. 12.6 ± 2.2 in hearts of ANG II-treated CTRL mice. Lactate production was also elevated in hearts of ANG II-treated STAT3 KO mice by 162% compared to ANG II-treated CTRL mice. Our findings indicate that STAT3 is important for maintaining contractile function and metabolic homeostasis in the hypertensive heart, and STAT3 deficiency promotes a switch toward glucose utilization.

Modification of methyl oleate for silicon-based biological lubricating base oil

A new kind of silicon-based biological lubricating base oil with good viscosity-temperature behavior, viscosity index, thermostability, oxidation stability and wear resistance performance was synthesized as a derivative of methyl oleate. Trimethylsilylation reaction was introduced to further improve methyl oleate oxidation stability and lubricity after epoxidation and open-ring reactions. The order of effectiveness of acid binding agent was N,N-diisopropylethylamine (DIEA)>pyridine>diethylamine>triethylamine, and the effects of various parameters on the trimethylsilylation reaction as well as on the silicon-oxygen bond stability and reaction yield were studied. A maximum yield of 34.54% was achieved at hydroxyl/trimethyl chlorosilane/DIEA molar ratio of 1:1.25:1, reaction temperature 40°C, reaction time 1.5h.

Biotinylation: a novel posttranslational modification linking cell autonomous circadian clocks with metabolism.

Circadian clocks are critical modulators of metabolism. However, mechanistic links between cell autonomous clocks and metabolic processes remain largely unknown. Here, we report that expression of the biotin transporter slc5a6 gene is decreased in hearts of two distinct genetic mouse models of cardiomyocyte-specific circadian clock disruption [i.e., cardiomyocyte-specific CLOCK mutant (CCM) and cardiomyocyte-specific BMAL1 knockout (CBK) mice]. Biotinylation is an obligate posttranslational modification for five mammalian carboxylases: acetyl-CoA carboxylase α (ACCα), ACCβ, pyruvate carboxylase (PC), methylcrotonyl-CoA carboxylase (MCC), and propionyl-CoA carboxylase (PCC). We therefore hypothesized that the cardiomyocyte circadian clock impacts metabolism through biotinylation. Consistent with decreased slc5a6 expression, biotinylation of all carboxylases is significantly decreased (10-46%) in CCM and CBK hearts. In association with decreased biotinylated ACC, oleate oxidation rates are increased in both CCM and CBK hearts. Consistent with decreased biotinylated MCC, leucine oxidation rates are significantly decreased in both CCM and CBK hearts, whereas rates of protein synthesis are increased. Importantly, feeding CBK mice with a biotin-enriched diet for 6 wk normalized myocardial 1) ACC biotinylation and oleate oxidation rates; 2) PCC/MCC biotinylation (and partially restored leucine oxidation rates); and 3) net protein synthesis rates. Furthermore, data suggest that the RRAGD/mTOR/4E-BP1 signaling axis is chronically activated in CBK and CCM hearts. Finally we report that the hepatocyte circadian clock also regulates both slc5a6 expression and protein biotinylation in the liver. Collectively, these findings suggest that biotinylation is a novel mechanism by which cell autonomous circadian clocks influence metabolic pathways.

Abstract 19844: Stromal Interaction Molecule 1 is Essential for the Maintenance of Cardiac Metabolism

The ER/SR Ca 2+ sensor, Stromal Interaction molecule 1 (STIM1), a key regulator of store-operated calcium entry is expressed in cardiomyocytes and has been implicated in regulating hypertrophic signaling. We have recently shown that mice with a cardiomyocyte-restricted deletion of STIM1 develop dilated cardiomyopathy. Given the importance of Ca 2+ in regulating cardiac metabolism we examined whether a lack of STIM1 alters cardiac metabolism. We found that hearts isolated from 20 week cr STIM1-KO mice exhibit significant changes in cardiac metabolism, observed by a significant reduction in both glucose oxidation (0.75 ± 0.06 v 0.46 ± 0.04 μmol/min/g dry wt, p &lt; 0.01) and net lactate release (15.38 ± 1.29 v 10.23 ± 0.87 μmol/min/g dry wt, p &lt;0.02) in an isolated perfused working heart model in comparison to control mice. These changes occurred independent of any changes in contractile function or oleate oxidation (0.22 ± 0.03 v 0.26 ± 0.02 μmol/min/g dry wt, ns ). Consistent with a reduction in glucose oxidation we also found significant increase in the expression of Pyruvate dehydrogenase kinase and a reduction in the expression of GLUT4 protein levels. Hearts from 20 week cr STIM1-KO contained an increased number of lipid droplets (3.35 ± 0.35 v 2.08 ± 0.20, no of lipid droplets per 4400x grid square, p &lt;0.002) and increased triglyceride levels (51.95 ± 5.84 v 32.55 ± 2.41 v 36.05 ± 1.73 mg/dL, p &lt; 0.05) in comparison to age-matched controls and cr STIM1-KO +/- hearts respectively. In addition to these metabolic changes there were was also significant disruption in mitochondrial morphology and structure in cr STIM1-KO; interesting these same abnormalities were also present in cr STIM1-KO +/- hearts. We found that 12 week cr STIM1-KO +/- and cr STIM1-KO hearts contained smaller mitochondria compared to controls and that cr STIM1-KO were significantly smaller than cr STIM1-KO +/- (1140.6 ± 28.3nm v 973.9 ± 15.8nm v 887.3 ± 17.1nm, p &lt; 0.01) These data demonstrate for the first time a novel yet critical role for STIM1 in regulating cardiac metabolism and in maintaining mitochondrial morphology and organization. This work was supported by NIH grant R21-HL-110366 (JCC) and an American Heart Association Greater Southeast Postdoctoral fellowship 15POST25260004 (HEC).