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Rosalind A Coleman - One of the best experts on this subject based on the ideXlab platform.
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long chain acyl coa synthetase 2 knockdown leads to decreased fatty acid oxidation in fat body and reduced reproductive capacity in the insect rhodnius prolixus
Biochimica et Biophysica Acta, 2016Co-Authors: Rosalind A Coleman, Michele Alvesbezerra, Eric L Klett, Iron F De Paula, Isabela Ramos, Katia C GondimAbstract:Long-chain Acyl-CoA esters are important intermediates in lipid metabolism and are synthesized from fatty acids by long-chain Acyl-CoA synthetases (ACSL). The hematophagous insect Rhodnius prolixus, a vector of Chagas' disease, produces glycerolipids in the midgut after a blood meal, which are stored as triacylglycerol in the fat body and eggs. We identified twenty Acyl-CoA synthetase genes in R. prolixus, two encoding ACSL isoforms (RhoprAcsl1 and RhoprAcsl2). RhoprAcsl1 transcripts increased in posterior midgut on the second day after feeding, and RhoprAcsl2 was highly transcribed on the tenth day. Both enzymes were expressed in Escherichia coli. Recombinant RhoprACSL1 and RhoprACSL2 had broad pH optima (7.5-9.5 and 6.5-9.5, respectively), were inhibited by triacsin C, and were rosiglitazone-insensitive. Both showed similar apparent Km for palmitic and oleic acid (2-6 μM), but different Km for arachidonic acid (0.5 and 6 μM for RhoprACSL1-Flag and RhoprACSL2-Flag, respectively). The knockdown of RhoprAcsl1 did not result in noticeable phenotypes. However, RhoprACSL2 deficient insects exhibited a 2.5-fold increase in triacylglycerol content in the fat body, and 90% decrease in fatty acid β-oxidation. RhoprAcsl2 knockdown also resulted in 20% increase in lifespan, delayed digestion, 30% reduced oviposition, and 50% reduction in egg hatching. Laid eggs and hatched nymphs showed remarkable alterations in morphology. In summary, R. prolixus ACSL isoforms have distinct roles on lipid metabolism. Although RhoprACSL1 functions remain unclear, we propose that RhoprACSL2 is the main contributor for the formation of the intracellular Acyl-CoA pool channeled for β-oxidation in the fat body, and is also required for normal reproduction.
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compartmentalized acyl coa metabolism in skeletal muscle regulates systemic glucose homeostasis
Diabetes, 2015Co-Authors: Lei O Li, Timothy R Koves, Deborah M Muoio, Olga Ilkayeva, Trisha J Grevengoed, David S Paul, Florencia Pascual, Christopher B Newgard, Rosalind A ColemanAbstract:The impaired capacity of skeletal muscle to switch between the oxidation of fatty acid (FA) and glucose is linked to disordered metabolic homeostasis. To understand how muscle FA oxidation affects systemic glucose, we studied mice with a skeletal muscle–specific deficiency of long-chain Acyl-CoA synthetase (ACSL)1. ACSL1 deficiency caused a 91% loss of ACSL-specific activity and a 60–85% decrease in muscle FA oxidation. Acsl1M−/− mice were more insulin sensitive, and, during an overnight fast, their respiratory exchange ratio was higher, indicating greater glucose use. During endurance exercise, Acsl1M−/− mice ran only 48% as far as controls. At the time that Acsl1M−/− mice were exhausted but control mice continued to run, liver and muscle glycogen and triacylglycerol stores were similar in both genotypes; however, plasma glucose concentrations in Acsl1M−/− mice were ∼40 mg/dL, whereas glucose concentrations in controls were ∼90 mg/dL. Excess use of glucose and the likely use of amino acids for fuel within muscle depleted glucose reserves and diminished substrate availability for hepatic gluconeogenesis. Surprisingly, the content of muscle Acyl-CoA at exhaustion was markedly elevated, indicating that Acyl-CoAs synthesized by other ACSL isoforms were not available for β-oxidation. This compartmentalization of Acyl-CoAs resulted in both an excessive glucose requirement and severely compromised systemic glucose homeostasis.
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diminished acyl coa synthetase isoform 4 activity in ins 832 13 cells reduces cellular epoxyeicosatrienoic acid levels and results in impaired glucose stimulated insulin secretion
Journal of Biological Chemistry, 2013Co-Authors: Eric L Klett, Olga Ilkayeva, Christopher B Newgard, Shufen Chen, Matthew L Edin, Darryl C Zeldin, Rosalind A ColemanAbstract:Abstract Glucose-stimulated insulin secretion (GSIS) in pancreatic beta-cells is potentiated by fatty acids (FA). The initial step in the metabolism of intracellular FA is the conversion to Acyl-CoA by long chain Acyl-CoA synthetases (Acsls). Because the predominantly expressed Acsl isoforms in INS 832/13 cells are Acsl4 and -5, we characterized the role of these Acsls in beta-cell function by using siRNA to knock down Acsl4 or Acsl5. Compared with control cells, an 80% suppression of Acsl4 decreased GSIS and FA-potentiated GSIS by 32 and 54%, respectively. Knockdown of Acsl5 did not alter GSIS. Acsl4 knockdown did not alter FA oxidation or long chain Acyl-CoA levels. With Acsl4 knockdown, incubation with 17 mm glucose increased media epoxyeicosatrienoic acids (EETs) and reduced cell membrane levels of EETs. Further, exogenous EETs reduced GSIS in INS 832/13 cells, and in Acsl4 knockdown cells, an EET receptor antagonist partially rescued GSIS. These results strongly suggest that Acsl4 activates EETs to form EET-CoAs that are incorporated into glycerophospholipids, thereby sequestering EETs. Exposing INS 832/13 cells to arachidonate or linoleate reduced Acsl4 mRNA and protein expression and reduced GSIS. These data indicate that Acsl4 modulates GSIS by regulating the levels of unesterified EETs and that arachidonate controls the expression of its activator Acsl4.
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acyl coenzyme a synthetases in metabolic control
Current Opinion in Lipidology, 2010Co-Authors: Jessica M Ellis, Jennifer L Frahm, Rosalind A ColemanAbstract:Purpose of reviewThe 11 long-chain (ACSL) and very long chain acyl-coenzyme A (Acyl-CoA) synthetases [(ACSVL)/fatty acid transport protein] are receiving considerable attention because it has become apparent that their individual functions are not redundant.Recent findingsRecent studies have focused
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triacsin c blocks de novo synthesis of glycerolipids and cholesterol esters but not recycling of fatty acid into phospholipid evidence for functionally separate pools of acyl coa
Biochemical Journal, 1997Co-Authors: R A Igal, P Wang, Rosalind A ColemanAbstract:The trafficking of Acyl-CoAs within cells is poorly understood. In order to determine whether newly synthesized Acyl-CoAs are equally available for the synthesis of all glycerolipids and cholesterol esters, we incubated human fibroblasts with [14C]oleate, [3H]arachidonate or [3H]glycerol in the presence or absence of triacsin C, a fungal metabolite that is a competitive inhibitor of Acyl-CoA synthetase. Triacsin C inhibited de novo synthesis from glycerol of triacylglycerol, diacylglycerol and cholesterol esters by more than 93%, and the synthesis of phospholipid by 83%. However, the incorporation of oleate or arachidonate into phospholipids appeared to be relatively unimpaired when triacsin was present. Diacylglycerol acyltransferase and lysophosphatidylcholine acyltransferase had similar dependences on palmitoyl-CoA in both liver and fibroblasts; thus it did not appear that Acyl-CoAs, when present at low concentrations, would be preferentially used to acylate lysophospholipids. We interpret these data to mean that, when fatty acid is not limiting, triacsin blocks the acylation of glycerol 3-phosphate and diacylglycerol, but not the reacylation of lysophospholipids. Two explanations are possible: (1) different Acyl-CoA synthetases exist that vary in their sensitivity to triacsin; (2) an independent mechanism channels Acyl-CoA towards phospholipid synthesis when little Acyl-CoA is available. In either case, the Acyl-CoAs available to acylate cholesterol, glycerol 3-phosphate, lysophosphatidic acid and diacylglycerol and those Acyl-CoAs that are used by lysophospholipid acyltransferases and by ceramide N-acyltransferase must reside in two non-mixing Acyl-CoA pools or, when Acyl-CoAs are limiting, they must be selectively channelled towards specific acyltransferase reactions.
Nathaniel W Snyder - One of the best experts on this subject based on the ideXlab platform.
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lc quadrupole orbitrap high resolution mass spectrometry enables stable isotope resolved simultaneous quantification and c isotopic labeling of acyl coenzyme a thioesters
Analytical and Bioanalytical Chemistry, 2016Co-Authors: Alexander J Frey, Sankha S Basu, Andrew J Worth, Sophie Trefely, Daniel R Feldman, Nathaniel W SnyderAbstract:Acyl-coenzyme A (Acyl-CoA) thioesters are evolutionarily conserved, compartmentalized, and energetically activated substrates for biochemical reactions. The ubiquitous involvement of Acyl-CoA thioesters in metabolism, including the tricarboxylic acid cycle, fatty acid metabolism, amino acid degradation, and cholesterol metabolism highlights the broad applicability of applied measurements of Acyl-CoA thioesters. However, quantitation of Acyl-CoA levels provides only one dimension of metabolic information and a more complete description of metabolism requires the relative contribution of different precursors to individual substrates and pathways. Using two distinct stable isotope labeling approaches, Acyl-CoA thioesters can be labeled with either a fixed [(13)C3(15)N1] label derived from pantothenate into the CoA moiety or via variable [(13)C] labeling into the acyl chain from metabolic precursors. Liquid chromatography-hybrid quadrupole/Orbitrap high-resolution mass spectrometry using parallel reaction monitoring, but not single ion monitoring, allowed the simultaneous quantitation of Acyl-CoA thioesters by stable isotope dilution using the [(13)C3(15)N1] label and measurement of the incorporation of labeled carbon atoms derived from [(13)C6]-glucose, [(13)C5(15)N2]-glutamine, and [(13)C3]-propionate. As a proof of principle, we applied this method to human B cell lymphoma (WSU-DLCL2) cells in culture to precisely describe the relative pool size and enrichment of isotopic tracers into acetyl-, succinyl-, and propionyl-CoA. This method will allow highly precise, multiplexed, and stable isotope-resolved determination of metabolism to refine metabolic models, characterize novel metabolism, and test modulators of metabolic pathways involving Acyl-CoA thioesters.
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production of stable isotope labeled acyl coenzyme a thioesters by yeast stable isotope labeling by essential nutrients in cell culture
Analytical Biochemistry, 2015Co-Authors: Robert C Parry, Jennifer A. Silvers, Kevin P Gillespie, Sankha S Basu, Jonathan I Millen, Andrew J Worth, Nathaniel W Snyder, Gregory Tombline, David S. GoldfarbAbstract:Abstract Acyl-coenzyme A (CoA) thioesters are key metabolites in numerous anabolic and catabolic pathways, including fatty acid biosynthesis and β-oxidation, the Krebs cycle, and cholesterol and isoprenoid biosynthesis. Stable isotope dilution-based methodology is the “gold standard” for quantitative analyses by mass spectrometry. However, chemical synthesis of families of stable isotope-labeled metabolites such as Acyl-CoA thioesters is impractical. Previously, we biosynthetically generated a library of stable isotope internal standard analogs of Acyl-CoA thioesters by exploiting the essential requirement in mammals and insects for pantothenic acid (vitamin B5) as a metabolic precursor for the CoA backbone. By replacing pantothenic acid in the cell medium with commercially available [13C315N1]-pantothenic acid, mammalian cells exclusively incorporated [13C315N1]-pantothenate into the biosynthesis of Acyl-CoA and Acyl-CoA thioesters. We have now developed a much more efficient method for generating stable isotope-labeled CoA and Acyl-CoAs from [13C315N1]-pantothenate using stable isotope labeling by essential nutrients in cell culture (SILEC) in Pan6-deficient yeast cells. Efficiency and consistency of labeling were also increased, likely due to the stringently defined and reproducible conditions used for yeast culture. The yeast SILEC method greatly enhances the ease of use and accessibility of labeled CoA thioesters and also provides proof of concept for generating other labeled metabolites in yeast mutants.
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metabolism of propionic acid to a novel acyl coenzyme a thioester by mammalian cell lines and platelets
Journal of Lipid Research, 2015Co-Authors: Sankha S Basu, Andrew J Worth, Nathaniel W Snyder, Clementina Mesaros, Ian A. BlairAbstract:Metabolism of propionate involves the activated acyl-thioester propionyl-CoA intermediate. We employed LC-MS/MS, LC-selected reaction monitoring/MS, and LC-high-resolution MS to investigate metabolism of propionate to Acyl-CoA intermediates. We discovered that propionyl-CoA can serve as a precursor to the direct formation of a new six-carbon mono-unsaturated Acyl-CoA. Time course and dose-response studies in human hepatocellular carcinoma HepG2 cells demonstrated that the six-carbon mono-unsaturated Acyl-CoA was propionate-dependent and underwent further metabolism over time. Studies utilizing [13C1]propionate and [13C3]propionate suggested a mechanism of fatty acid synthesis, which maintained all six-carbon atoms from two propionate molecules. Metabolism of 2,2-[2H2]propionate to the new six-carbon mono-unsaturated Acyl-CoA resulted in the complete loss of two deuterium atoms, indicating modification at C2 of the propionyl moiety. Coelution experiments and isotopic tracer studies confirmed that the new Acyl-CoA was trans-2-methyl-2-pentenoyl-CoA. Acyl-CoA profiles following treatment of HepG2 cells with mono-unsaturated six-carbon fatty acids also supported this conclusion. Similar results were obtained with human platelets, mouse hepatocellular carcinoma Hepa1c1c7 cells, human bronchoalveolar carcinoma H358 cells, and human colon adenocarcinoma LoVo cells. Interestingly, trans-2-methyl-2-pentenoyl-CoA corresponds to a previously described acylcarnitine tentatively described in patients with propionic and methylmalonic acidemia. We have proposed a mechanism for this metabolic route consistent with all of the above findings.
Jens Knudsen - One of the best experts on this subject based on the ideXlab platform.
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acyl coa esters antagonize the effects of ligands on peroxisome proliferator activated receptor alpha conformation dna binding and interaction with co factors
Journal of Biological Chemistry, 2001Co-Authors: Morten Elholm, Rolf K Berge, Claus Jorgensen, Annem Krogsdam, Dorte Holst, Irina Kratchmarova, Martin Gottlicher, Janake Gustafsson, Torgeir Flatmark, Jens KnudsenAbstract:Abstract The peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated transcription factor and a key regulator of lipid homeostasis. Numerous fatty acids and eicosanoids serve as ligands and activators for PPARα. Here we demonstrate thatS-hexadecyl-CoA, a nonhydrolyzable palmitoyl-CoA analog, antagonizes the effects of agonists on PPARα conformation and function in vitro. In electrophoretic mobility shift assays, S-hexadecyl-CoA prevented agonist-induced binding of the PPARα-retinoid X receptor α heterodimer to the Acyl-CoA oxidase peroxisome proliferator response element. PPARα bound specifically to immobilized palmitoyl-CoA and Wy14643, but not BRL49653, abolished binding. S-Hexadecyl-CoA increased in a dose-dependent and reversible manner the sensitivity of PPARα to chymotrypsin digestion, and theS-hexadecyl-CoA-induced sensitivity required a functional PPARα ligand-binding pocket. S-Hexadecyl-CoA prevented ligand-induced interaction between the co-activator SRC-1 and PPARα but increased recruitment of the nuclear receptor co-repressor NCoR. In cells, the concentration of free Acyl-CoA esters is kept in the low nanomolar range due to the buffering effect of high affinity Acyl-CoA-binding proteins, especially the Acyl-CoA-binding protein. By using PPARα expressed in Sf21 cells for electrophoretic mobility shift assays, we demonstrate that S-hexadecyl-CoA was able to increase the mobility of the PPARα-containing heterodimer even in the presence of a molar excess of Acyl-CoA-binding protein, mimicking the conditions found in vivo.
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the structural basis of acyl coenzyme a dependent regulation of the transcription factor fadr
The EMBO Journal, 2001Co-Authors: Daan M F Van Aalten, Jens Knudsen, Concetta C DirussoAbstract:FadR is an Acyl-CoA-responsive transcription factor, regulating fatty acid biosynthetic and degradation genes in Escherichia coli. The apo-protein binds DNA as a homodimer, an interaction that is disrupted by binding of Acyl-CoA: The recently described structure of apo-FadR shows a DNA binding domain coupled to an Acyl-CoA binding domain with a novel fold, but does not explain how binding of the Acyl-CoA effector molecule > 30 A away from the DNA binding site affects transcriptional regulation. Here, we describe the structures of the FadR-operator and FadR- myristoyl-CoA binary complexes. The FadR-DNA complex reveals a novel winged helix-turn-helix protein-DNA interaction, involving sequence-specific contacts from the wing to the minor groove. Binding of Acyl-CoA results in dramatic conformational changes throughout the protein, with backbone shifts up to 4.5 A. The net effect is a rearrangement of the DNA binding domains in the dimer, resulting in a change of 7.2 A in separation of the DNA recognition helices and the loss of DNA binding, revealing the molecular basis of Acyl-CoA-responsive regulation.
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detection of acyl coa binding protein in human red blood cells and investigation of its role in membrane phospholipid renewal
Biochemical Journal, 1995Co-Authors: Henrik Fyrst, Jens Knudsen, Mary Ann Schott, Bertram H Lubin, Frans A KuypersAbstract:Acyl-CoA-binding protein (ACBP) has been identified in a number of tissues and shown to affect the intracellular distribution and utilization of Acyl-CoA. We have detected ACBP in the cytosol but not the membrane of human red blood cells and, using an e.l.i.s.a. with antibodies prepared against human liver ACBP, found that its concentration was 0.5 microM. To investigate the role of ACBP in human red blood cells, we added purified human liver ACBP and radiolabelled Acyl-CoA to isolated membranes from these cells. ACBP prevented high concentrations of Acyl-CoA from binding to the membrane but could not keep the Acyl-CoA in the aqueous phase at low concentrations. This suggested the presence of a pool in the membrane with a binding affinity for Acyl-CoA that was greater than that of ACBP for Acyl-CoA. In the presence of lysophospholipid, this membrane-bound pool of Acyl-CoA was rapidly used as a substrate by Acyl-CoA:lysophospholipid acyltransferase (LAT) to generate phospholipid from lysophospholipid. We also found that ACBP-bound Acyl-CoA was preferred over free Acyl-CoA as a substrate by LAT. These results are the first documentation that human red blood cells contain ACBP and that this protein can affect the utilization of Acyl-CoA in plasma membranes of these cells. The interactions between Acyl-CoA, ACBP and the membrane suggest that there are several pools of Acyl-CoA in the human red blood cell and that ACBP may have a role in regulating their distribution and fate.
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acyl coa binding protein acbp can mediate intermembrane acyl coa transport and donate acyl coa for beta oxidation and glycerolipid synthesis
Biochemical Journal, 1994Co-Authors: J T Rasmussen, Nils J Faergeman, Karsten Kristiansen, Jens KnudsenAbstract:The dissociation constants for octanoyl-CoA, dodecanoyl-CoA and hexadecanoyl-CoA binding to Acyl-CoA-binding protein (ACBP) were determined by using titration microcalorimetry. The KD values obtained, (0.24 +/- 0.02) x 10(-6) M, (0.65 +/- 0.2) x 10(-8) M and (0.45 +/- 0.2) x 10(-13) M respectively, were much lower than expected. ACBP was able to extract hexadecanoyl-CoA from phosphatidylcholine membranes immobilized on a nitrocellulose membrane. The Acyl-CoA/ACBP complex formed was able to transport Acyl-CoA to mitochondria or microsomes in suspension, or to microsomes immobilized on a nitrocellulose membrane, and to donate them to beta-oxidation or glycerolipid synthesis in mitochondria or microsomes, respectively.
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the function of acyl coa binding protein acbp diazepam binding inhibitor dbi
Molecular and Cellular Biochemistry, 1993Co-Authors: Jens Knudsen, J T Rasmussen, Susanne Mandrup, Per Hove Andreasen, Flemming M Poulsen, Karsten KristiansenAbstract:Acyl-CoA-binding protein has been isolated independently by five different groups based on its ability to (1) displace diazepam from the GABAA receptor, (2) affect cell growth, (3) induce medium-chain Acyl-CoA-ester synthesis, (4) stimulate steroid hormone synthesis, and (5) affect glucose-induced insulin secretion. In this survey evidence is presented to show that ACBP is able to act as an intracellular Acyl-CoA transporter and Acyl-CoA pool former. The rat ACBP genomic gene consists of 4 exons and is actively expressed in all tissues tested with highest concentration being found in liver. ACBP consists of 86 amino acid residues and contains 4 α-helices which are folded into a boomerang type of structure with α-helices 1, 2 and 4 in the one arm and α-helix 3 and an open loop in the other arm of the boomerang. ACBP is able to stimulate mitochondrial Acyl-CoA synthetase by removing Acyl-CoA esters from the enzyme. ACBP is also able to desorb Acyl-CoA esters from immobilized membranes and transport and deliver these for mitochondrial β-oxidation. ACBP efficiently protects acetyl-CoA carboxylase and the mitochondrial ADP/ATP translocase against Acyl-CoA inhibition. Finally, ACBP is shown to be able to act as an intracellular Acyl-CoA pool former by overexpression in yeast. The possible role of ACBP in lipid metabolism is discussed.
Jessica M Ellis - One of the best experts on this subject based on the ideXlab platform.
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mouse cardiac acyl coenzyme a synthetase 1 deficiency impairs fatty acid oxidation and induces cardiac hypertrophy
Molecular and Cellular Biology, 2011Co-Authors: Jessica M Ellis, Timothy R Koves, Steven M Watkins, Deborah M Muoio, Shannon M Mentock, Michael A Depetrillo, Shiraj Sen, Gary W Cline, Heinrich Taegtmeyer, Gerald I ShulmanAbstract:Long-chain acyl coenzyme A (Acyl-CoA) synthetase isoform 1 (ACSL1) catalyzes the synthesis of Acyl-CoA from long-chain fatty acids and contributes the majority of cardiac long-chain Acyl-CoA synthetase activity. To understand its functional role in the heart, we studied mice lacking ACSL1 globally (Acsl1T−/−) and mice lacking ACSL1 in heart ventricles (Acsl1H−/−) at different times. Compared to littermate controls, heart ventricular ACSL activity in Acsl1T−/− mice was reduced more than 90%, Acyl-CoA content was 65% lower, and long-chain acyl-carnitine content was 80 to 90% lower. The rate of [14C]palmitate oxidation in both heart homogenate and mitochondria was 90% lower than in the controls, and the maximal rates of [14C]pyruvate and [14C]glucose oxidation were each 20% higher. The mitochondrial area was 54% greater than in the controls with twice as much mitochondrial DNA, and the mRNA abundance of Pgc1α and Errα increased by 100% and 41%, respectively. Compared to the controls, Acsl1T−/− and Acsl1H−/− hearts were hypertrophied, and the phosphorylation of S6 kinase, a target of mammalian target of rapamycin (mTOR) kinase, increased 5-fold. Our data suggest that ACSL1 is required to synthesize the Acyl-CoAs that are oxidized by the heart, and that without ACSL1, diminished fatty acid (FA) oxidation and compensatory catabolism of glucose and amino acids lead to mTOR activation and cardiac hypertrophy without lipid accumulation or immediate cardiac dysfunction.
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acyl coenzyme a synthetases in metabolic control
Current Opinion in Lipidology, 2010Co-Authors: Jessica M Ellis, Jennifer L Frahm, Rosalind A ColemanAbstract:Purpose of reviewThe 11 long-chain (ACSL) and very long chain acyl-coenzyme A (Acyl-CoA) synthetases [(ACSVL)/fatty acid transport protein] are receiving considerable attention because it has become apparent that their individual functions are not redundant.Recent findingsRecent studies have focused
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liver specific loss of long chain acyl coa synthetase 1 decreases triacylglycerol synthesis and β oxidation and alters phospholipid fatty acid composition
Journal of Biological Chemistry, 2009Co-Authors: Lei O Li, Jessica M Ellis, Heather A Paich, Shuli Wang, Nan Gong, George N Altshuller, Randy J Thresher, Timothy R Koves, Steven M Watkins, Deborah M MuoioAbstract:In mammals, a family of five Acyl-CoA synthetases (ACSLs), each the product of a separate gene, activates long chain fatty acids to form Acyl-CoAs. Because the ACSL isoforms have overlapping preferences for fatty acid chain length and saturation and are expressed in many of the same tissues, the individual function of each isoform has remained uncertain. Thus, we constructed a mouse model with a liver-specific knock-out of ACSL1, a major ACSL isoform in liver. Eliminating ACSL1 in liver resulted in a 50% decrease in total hepatic ACSL activity and a 25–35% decrease in long chain Acyl-CoA content. Although the content of triacylglycerol was unchanged in Acsl1L−/− liver after mice were fed either low or high fat diets, in isolated primary hepatocytes the absence of ACSL1 diminished the incorporation of [14C]oleate into triacylglycerol. Further, small but consistent increases were observed in the percentage of 16:0 in phosphatidylcholine and phosphatidylethanolamine and of 18:1 in phosphatidylethanolamine and lysophosphatidylcholine, whereas concomitant decreases were seen in 18:0 in phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and lysophosphatidylcholine. In addition, decreases in long chain acylcarnitine content and diminished production of acid-soluble metabolites from [14C]oleate suggested that hepatic ACSL1 is important for mitochondrial β-oxidation of long chain fatty acids. Because the Acsl1L−/− mice were not protected from developing either high fat diet-induced hepatic steatosis or insulin resistance, our study suggests that lowering the content of hepatic Acyl-CoA without a concomitant decrease in triacylglycerol and other lipid intermediates is insufficient to protect against hepatic insulin resistance.
Deborah M Muoio - One of the best experts on this subject based on the ideXlab platform.
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compartmentalized acyl coa metabolism in skeletal muscle regulates systemic glucose homeostasis
Diabetes, 2015Co-Authors: Lei O Li, Timothy R Koves, Deborah M Muoio, Olga Ilkayeva, Trisha J Grevengoed, David S Paul, Florencia Pascual, Christopher B Newgard, Rosalind A ColemanAbstract:The impaired capacity of skeletal muscle to switch between the oxidation of fatty acid (FA) and glucose is linked to disordered metabolic homeostasis. To understand how muscle FA oxidation affects systemic glucose, we studied mice with a skeletal muscle–specific deficiency of long-chain Acyl-CoA synthetase (ACSL)1. ACSL1 deficiency caused a 91% loss of ACSL-specific activity and a 60–85% decrease in muscle FA oxidation. Acsl1M−/− mice were more insulin sensitive, and, during an overnight fast, their respiratory exchange ratio was higher, indicating greater glucose use. During endurance exercise, Acsl1M−/− mice ran only 48% as far as controls. At the time that Acsl1M−/− mice were exhausted but control mice continued to run, liver and muscle glycogen and triacylglycerol stores were similar in both genotypes; however, plasma glucose concentrations in Acsl1M−/− mice were ∼40 mg/dL, whereas glucose concentrations in controls were ∼90 mg/dL. Excess use of glucose and the likely use of amino acids for fuel within muscle depleted glucose reserves and diminished substrate availability for hepatic gluconeogenesis. Surprisingly, the content of muscle Acyl-CoA at exhaustion was markedly elevated, indicating that Acyl-CoAs synthesized by other ACSL isoforms were not available for β-oxidation. This compartmentalization of Acyl-CoAs resulted in both an excessive glucose requirement and severely compromised systemic glucose homeostasis.
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mouse cardiac acyl coenzyme a synthetase 1 deficiency impairs fatty acid oxidation and induces cardiac hypertrophy
Molecular and Cellular Biology, 2011Co-Authors: Jessica M Ellis, Timothy R Koves, Steven M Watkins, Deborah M Muoio, Shannon M Mentock, Michael A Depetrillo, Shiraj Sen, Gary W Cline, Heinrich Taegtmeyer, Gerald I ShulmanAbstract:Long-chain acyl coenzyme A (Acyl-CoA) synthetase isoform 1 (ACSL1) catalyzes the synthesis of Acyl-CoA from long-chain fatty acids and contributes the majority of cardiac long-chain Acyl-CoA synthetase activity. To understand its functional role in the heart, we studied mice lacking ACSL1 globally (Acsl1T−/−) and mice lacking ACSL1 in heart ventricles (Acsl1H−/−) at different times. Compared to littermate controls, heart ventricular ACSL activity in Acsl1T−/− mice was reduced more than 90%, Acyl-CoA content was 65% lower, and long-chain acyl-carnitine content was 80 to 90% lower. The rate of [14C]palmitate oxidation in both heart homogenate and mitochondria was 90% lower than in the controls, and the maximal rates of [14C]pyruvate and [14C]glucose oxidation were each 20% higher. The mitochondrial area was 54% greater than in the controls with twice as much mitochondrial DNA, and the mRNA abundance of Pgc1α and Errα increased by 100% and 41%, respectively. Compared to the controls, Acsl1T−/− and Acsl1H−/− hearts were hypertrophied, and the phosphorylation of S6 kinase, a target of mammalian target of rapamycin (mTOR) kinase, increased 5-fold. Our data suggest that ACSL1 is required to synthesize the Acyl-CoAs that are oxidized by the heart, and that without ACSL1, diminished fatty acid (FA) oxidation and compensatory catabolism of glucose and amino acids lead to mTOR activation and cardiac hypertrophy without lipid accumulation or immediate cardiac dysfunction.
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liver specific loss of long chain acyl coa synthetase 1 decreases triacylglycerol synthesis and β oxidation and alters phospholipid fatty acid composition
Journal of Biological Chemistry, 2009Co-Authors: Lei O Li, Jessica M Ellis, Heather A Paich, Shuli Wang, Nan Gong, George N Altshuller, Randy J Thresher, Timothy R Koves, Steven M Watkins, Deborah M MuoioAbstract:In mammals, a family of five Acyl-CoA synthetases (ACSLs), each the product of a separate gene, activates long chain fatty acids to form Acyl-CoAs. Because the ACSL isoforms have overlapping preferences for fatty acid chain length and saturation and are expressed in many of the same tissues, the individual function of each isoform has remained uncertain. Thus, we constructed a mouse model with a liver-specific knock-out of ACSL1, a major ACSL isoform in liver. Eliminating ACSL1 in liver resulted in a 50% decrease in total hepatic ACSL activity and a 25–35% decrease in long chain Acyl-CoA content. Although the content of triacylglycerol was unchanged in Acsl1L−/− liver after mice were fed either low or high fat diets, in isolated primary hepatocytes the absence of ACSL1 diminished the incorporation of [14C]oleate into triacylglycerol. Further, small but consistent increases were observed in the percentage of 16:0 in phosphatidylcholine and phosphatidylethanolamine and of 18:1 in phosphatidylethanolamine and lysophosphatidylcholine, whereas concomitant decreases were seen in 18:0 in phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and lysophosphatidylcholine. In addition, decreases in long chain acylcarnitine content and diminished production of acid-soluble metabolites from [14C]oleate suggested that hepatic ACSL1 is important for mitochondrial β-oxidation of long chain fatty acids. Because the Acsl1L−/− mice were not protected from developing either high fat diet-induced hepatic steatosis or insulin resistance, our study suggests that lowering the content of hepatic Acyl-CoA without a concomitant decrease in triacylglycerol and other lipid intermediates is insufficient to protect against hepatic insulin resistance.
