Malonyl-CoA metabolism in cardiac myocytes and its relevance to the control of fatty acid oxidation

1. Viable myocytes were obtained from rat hearts. Oxidation of [1-14C]palmitate by these cells could be decreased by the addition of glucose (5 mM) or lactate (2 mM). In the presence of glucose, insulin decreased and adrenaline increased palmitate oxidation. 2. The myocytes contained activities of ATP citrate-lyase, acetyl-CoA carboxylase and the condensing enzyme of the fatty acid elongation system. No fatty acid synthase activity was demonstrable in myocytes. 3. In rat hearts perfused with 5 mM glucose, malonyl-CoA content was acutely raised by insulin. In the presence of glucose+insulin, perfusion with palmitate or adrenaline decreased the malonyl-CoA content. 4. It is concluded that malonyl-CoA can be synthesized within cardiac myocytes and that the level of this metabolite can be acutely regulated. This is likely to have consequences for the regulation of carnitine palmitoyltransferase in the heart.

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Regulation of fatty acid oxidation of the heart by MCD and ACC during contractile stimulation

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1999.277.4.e772 ◽

1999 ◽

Vol 277 (4) ◽

pp. E772-E777 ◽

Cited By ~ 26

Author(s):

Gary W. Goodwin ◽

Heinrich Taegtmeyer

Keyword(s):

Fatty Acid ◽

Fatty Acid Oxidation ◽

Acid Oxidation ◽

Acetyl Coa Carboxylase ◽

Physiological Conditions ◽

Heart Work ◽

Rat Hearts ◽

Malonyl Coa ◽

Work Transition ◽

Endogenous Lipids

We tested the hypothesis that the level of malonyl-CoA, as well as the corresponding rate of total fatty acid oxidation of the heart, is regulated by the opposing actions of acetyl-CoA carboxylase (ACC) and malonyl-CoA decarboxylase (MCD). We used isolated working rat hearts perfused under physiological conditions. MCD in heart homogenates was measured specifically by14CO2production from [3-14C]malonyl-CoA, and ACC was measured specifically based on the portion of total carboxylase that is citrate sensitive. Increased heart work (1 μM epinephrine + 40% increase in afterload) elicited a 40% increase in total β-oxidation of exogenous plus endogenous lipids, accompanied by a 33% decrease in malonyl-CoA. The basal activity and citrate sensitivity of ACC (reflecting its phosphorylation state) and citrate content were unchanged. AMP levels were also unchanged. MCD activity, when measured at a subsaturating concentration of malonyl-CoA (50 μM), was increased by 55%. We conclude that physiological increments in AMP during the work transition are insufficient to promote ACC phosphorylation by AMP-stimulated protein kinase. Rather, increased fatty acid oxidation results from increased malonyl-CoA degradation by MCD.

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RNA-seq reveals novel mechanistic targets of withaferin A in prostate cancer cells

Carcinogenesis ◽

10.1093/carcin/bgaa009 ◽

2020 ◽

Vol 41 (6) ◽

pp. 778-789 ◽

Cited By ~ 5

Author(s):

Su-Hyeong Kim ◽

Eun-Ryeong Hahm ◽

Krishna B Singh ◽

Sruti Shiva ◽

Jacob Stewart-Ornstein ◽

...

Keyword(s):

Prostate Cancer ◽

Fatty Acid ◽

Fatty Acid Synthase ◽

Acid Synthesis ◽

Acetyl Coa Carboxylase ◽

Rna Seq ◽

Atp Citrate Lyase ◽

Acetyl Coa ◽

Citrate Lyase

Abstract Withaferin A (WA) is a promising phytochemical exhibiting in vitro and in vivo anticancer activities against prostate and other cancers, but the mechanism of its action is not fully understood. In this study, we performed RNA-seq analysis using 22Rv1 human prostate cancer cell line to identify mechanistic targets of WA. Kyoto Encyclopedia of Genes and Genomes pathway analysis of the differentially expressed genes showed most significant enrichment of genes associated with metabolism. These results were validated using LNCaP and 22Rv1 human prostate cancer cells and Hi-Myc transgenic mice as models. The intracellular levels of acetyl-CoA, total free fatty acids and neutral lipids were decreased significantly following WA treatment in both cells, which was accompanied by downregulation of mRNA (confirmed by quantitative reverse transcription-polymerase chain reaction) and protein levels of key fatty acid synthesis enzymes, including ATP citrate lyase, acetyl-CoA carboxylase 1, fatty acid synthase and carnitine palmitoyltransferase 1A. Ectopic expression of c-Myc, but not constitutively active Akt, conferred a marked protection against WA-mediated suppression of acetyl-CoA carboxylase 1 and fatty acid synthase protein expression, and clonogenic cell survival. WA was a superior inhibitor of cell proliferation and fatty acid synthesis in comparison with known modulators of fatty acid metabolism including cerulenin and etomoxir. Intraperitoneal WA administration to Hi-Myc transgenic mice (0.1 mg/mouse, three times/week for 5 weeks) also resulted in a significant decrease in circulating levels of total free fatty acids and phospholipids, and expression of ATP citrate lyase, acetyl-CoA carboxylase 1, fatty acid synthase and carnitine palmitoyltransferase 1A proteins in the prostate in vivo.

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Glucocorticoid regulation of fatty acid synthase gene expression in fetal rat lung

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1993.265.2.l140 ◽

1993 ◽

Vol 265 (2) ◽

pp. L140-L147 ◽

Cited By ~ 6

Author(s):

Z. X. Xu ◽

W. Stenzel ◽

S. M. Sasic ◽

D. A. Smart ◽

S. A. Rooney

Keyword(s):

Fatty Acid ◽

Fatty Acid Synthase ◽

Fatty Acid Biosynthesis ◽

Fetal Lung ◽

Acetyl Coa Carboxylase ◽

Rat Lung ◽

Acid Biosynthesis ◽

Atp Citrate Lyase ◽

Acetyl Coa ◽

Citrate Lyase

There are developmental and glucocorticoid-induced increases in the rate of fatty acid biosynthesis and in the activity of fatty acid synthase in late gestation fetal lung. We have now measured mRNA levels of fatty acid synthase and of two other enzymes of fatty acid biosynthesis, ATP citrate lyase and acetyl-CoA carboxylase, in developing fetal and postnatal rat lung and in fetal lung explants cultured with and without dexamethasone. There was a developmental increase in the mRNA for fatty acid synthase with the maximum level being reached on fetal day 21 (term is fetal day 22). This profile was similar to that reported for de novo fatty acid synthesis and fatty acid synthase activity. There was a similar but less pronounced developmental increase in the mRNA for ATP citrate lyase and a corresponding increase in its activity. There was no developmental change in the mRNA for acetyl-CoA carboxylase. Dexamethasone increased the level of fatty acid synthase mRNA approximately threefold but had no effect on those for ATP citrate lyase and acetyl-CoA carboxylase. The effect of dexamethasone on fatty acid synthase mRNA was rapid, biphasic, and partly inhibited by actinomycin D and cycloheximide. We conclude that glucocorticoids increase expression of the gene for fatty acid synthase in fetal lung. The effect of the hormone appears to be due to increased transcription and post-transcriptional events and is dependent on protein synthesis.

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Zonation of hepatic lipogenic enzymes identified by dual-digitonin-pulse perfusion

Biochemical Journal ◽

10.1042/bj2590821 ◽

1989 ◽

Vol 259 (3) ◽

pp. 821-829 ◽

Cited By ~ 17

Author(s):

J L Evans ◽

B Quistorff ◽

L A Witters

Keyword(s):

Fatty Acid ◽

Fatty Acid Synthesis ◽

Fatty Acid Synthase ◽

Acid Synthesis ◽

Male Rats ◽

Male Rat ◽

Acetyl Coa Carboxylase ◽

Atp Citrate Lyase ◽

Acetyl Coa ◽

Citrate Lyase

The zonal distribution within rat liver of acetyl-CoA carboxylase, ATP citrate-lyase and fatty acid synthase, the principal enzymes of fatty acid synthesis, was investigated by using dual-digitonin-pulse perfusion. Analysis of enzyme mass by immunoblotting revealed that, in normally feeding male rats, the periportal/perivenous ratio of acetyl-CoA carboxylase mass was 1.9. The periportal/perivenous ratio of ATP citrate-lyase mass was 1.4, and fatty acid synthase exhibited the largest periportal/perivenous mass gradient, having a ratio of 3.1. This pattern of enzyme distribution was observed in male rats only; in females, the periportal/perivenous ratio of enzyme mass was nearly equal. The periportal/perivenous gradients for acetyl-CoA carboxylase, ATP citrate-lyase and fatty acid synthase observed in fed (and fasted) males were abolished when animals were fasted (48 h) and refed (30 h) with a high-carbohydrate/low-fat diet. As determined by enzyme assay of eluates obtained from the livers of normally feeding male rats, there is also periportal zonation of acetyl-CoA carboxylase activity, expressed either as units per mg of eluted protein or units per mg of acetyl-CoA carboxylase protein, suggesting the existence of gradients in both enzyme mass and specific activity. From these results, we conclude that the enzymes of fatty acid synthesis are zonated periportally in the liver of the normally feeding male rat.

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Probing the link between citrate and malonyl-CoA in perfused rat hearts

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00244.2002 ◽

2002 ◽

Vol 283 (4) ◽

pp. H1379-H1386 ◽

Cited By ~ 17

Author(s):

Myriame Poirier ◽

Geneviève Vincent ◽

Aneta E. Reszko ◽

Bertrand Bouchard ◽

Joanne K. Kelleher ◽

...

Keyword(s):

Carbon Sources ◽

Acid Oxidation ◽

Atp Citrate Lyase ◽

Acetyl Coa ◽

Rat Hearts ◽

Citrate Lyase ◽

Malonyl Coa ◽

Perfused Rat Hearts ◽

Citrate Release

Little is known about the sources of cytosolic acetyl-CoA used for the synthesis of malonyl-CoA, a key regulator of fatty acid oxidation in the heart. We tested the hypothesis that citrate provides acetyl-CoA for malonyl-CoA synthesis after its mitochondrial efflux and cleavage by cytosolic ATP-citrate lyase. We expanded on a previous study where we characterized citrate release from perfused rat hearts (Vincent G, Comte B, Poirier M, and Des Rosiers C. Citrate release by perfused rat hearts: a window on mitochondrial cataplerosis. Am J Physiol Endocrinol Metab 278: E846–E856, 2000). In the present study, we show that citrate release rates, ranging from 6 to 22 nmol/min, can support a net increase in malonyl-CoA concentrations induced by changes in substrate supply, at most 0.7 nmol/min. In experiments with [U-13C](lactate + pyruvate) and [1-13C]oleate, we show that the acetyl moiety of malonyl-CoA is derived from both pyruvate and long-chain fatty acids. This 13C-labeling of malonyl-CoA occurred without any changes in its concentration. Hydroxycitrate, an inhibitor of ATP-citrate lyase, prevents increases in malonyl-CoA concentrations and decreases its labeling from [U-13C](lactate + pyruvate). Our data support at least a partial role of citrate in the transfer from the mitochondria to cytosol of acetyl units for malonyl-CoA synthesis. In addition, they provide a dynamic picture of malonyl-CoA metabolism: even when the malonyl-CoA concentration remains constant, there appears to be a constant need to supply acetyl-CoA from various carbon sources, both carbohydrates and lipids, for malonyl-CoA synthesis.

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Malonyl-CoA regulation in skeletal muscle: its link to cell citrate and the glucose-fatty acid cycle

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1997.272.4.e641 ◽

1997 ◽

Vol 272 (4) ◽

pp. E641-E648 ◽

Cited By ~ 32

Author(s):

A. K. Saha ◽

D. Vavvas ◽

T. G. Kurowski ◽

A. Apazidis ◽

L. A. Witters ◽

...

Keyword(s):

Skeletal Muscle ◽

Fatty Acid ◽

Pancreatic Beta Cell ◽

Acid Oxidation ◽

Atp Citrate Lyase ◽

Acetyl Coa ◽

Acid Cycle ◽

Citrate Lyase ◽

Malonyl Coa ◽

Glucose Fatty Acid Cycle

Malonyl-CoA is an inhibitor of carnitine palmitoyltransferase I, the enzyme that controls the oxidation of fatty acids by regulating their transfer into the mitochondria. Despite this, knowledge of how malonyl-CoA levels are regulated in skeletal muscle, the major site of fatty acid oxidation, is limited. Two- to fivefold increases in malonyl-CoA occur in rat soleus muscles incubated with glucose or glucose plus insulin for 20 min [Saha, A. K., T. G. Kurowski, and N. B. Ruderman. Am. J. Physiol. 269 (Endocrinol. Metab. 32): E283-E289, 1995]. In addition, as reported here, acetoacetate in the presence of glucose increases malonyl-CoA levels in the incubated soleus. The increases in malonyl-CoA in all of these situations correlated closely with increases in the concentration of citrate (r2 = 0.64) and to an even greater extent the sum of citrate plus malate (r2 = 0.90), an antiporter for citrate efflux from the mitochondria. Where measured, no increase in the activity of acetyl-CoA carboxylase (ACC) was found. Inhibition of ATP citrate lyase with hydroxycitrate markedly diminished the increases in malonyl-CoA in these muscles, indicating that citrate was the major substrate for the malonyl-CoA precursor, cytosolic acetyl-CoA. Studies with enzyme purified by immunoprecipitation indicated that the observed increases in citrate could have also allosterically activated ACC. The results suggest that in the presence of glucose, insulin and acetoacetate acutely increase malonyl-CoA levels in the incubated soleus by increasing the cytosolic concentration of citrate. This novel mechanism could complement the glucose-fatty acid cycle in determining how muscle chooses its fuels. It could also provide a means by which glucose acutely modulates signal transduction in muscle and other cells (e.g., the pancreatic beta-cell) in which its metabolism is determined by substrate availability.

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Effect of phosphorylation by AMP-activated protein kinase on palmitoyl-CoA inhibition of skeletal muscle acetyl-CoA carboxylase

Journal of Applied Physiology ◽

10.1152/japplphysiol.00621.2004 ◽

2005 ◽

Vol 98 (4) ◽

pp. 1221-1227 ◽

Cited By ~ 7

Author(s):

D. S. Rubink ◽

W. W. Winder

Keyword(s):

Skeletal Muscle ◽

Fatty Acid ◽

Protein Kinase ◽

Fatty Acid Oxidation ◽

Acid Oxidation ◽

Acetyl Coa Carboxylase ◽

Acetyl Coa ◽

Oxidation Rates ◽

Malonyl Coa ◽

Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) has previously been demonstrated to phosphorylate and inactivate skeletal muscle acetyl-CoA carboxylase (ACC), the enzyme responsible for synthesis of malonyl-CoA, an inhibitor of carnitine palmitoyltransferase 1 and fatty acid oxidation. Contraction-induced activation of AMPK with subsequent phosphorylation/inactivation of ACC has been postulated to be responsible in part for the increase in fatty acid oxidation that occurs in muscle during exercise. These studies were designed to answer the question: Does phosphorylation of ACC by AMPK make palmitoyl-CoA a more effective inhibitor of ACC? Purified rat muscle ACC was subjected to phosphorylation by AMPK. Activity was determined on nonphosphorylated and phosphorylated ACC preparations at acetyl-CoA concentrations ranging from 2 to 500 μM and at palmitoyl-CoA concentrations ranging from 0 to 100 μM. Phosphorylation resulted in a significant decline in the substrate saturation curve at all palmitoyl-CoA concentrations. The inhibitor constant for palmitoyl-CoA inhibition of ACC was reduced from 1.7 ± 0.25 to 0.85 ± 0.13 μM as a consequence of phosphorylation. At 0.5 mM citrate, ACC activity was reduced to 13% of control values in response to the combination of phosphorylation and 10 μM palmitoyl-CoA. Skeletal muscle ACC is more potently inhibited by palmitoyl-CoA after having been phosphorylated by AMPK. This may contribute to low-muscle malonyl-CoA values and increasing fatty acid oxidation rates during long-term exercise when plasma fatty acid concentrations are elevated.

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AICA riboside increases AMP-activated protein kinase, fatty acid oxidation, and glucose uptake in rat muscle

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1997.273.6.e1107 ◽

1997 ◽

Vol 273 (6) ◽

pp. E1107-E1112 ◽

Cited By ~ 226

Author(s):

G. F. Merrill ◽

E. J. Kurth ◽

D. G. Hardie ◽

W. W. Winder

Keyword(s):

Skeletal Muscle ◽

Fatty Acid ◽

Protein Kinase ◽

Glucose Uptake ◽

Fatty Acid Oxidation ◽

Fold Increase ◽

Acid Oxidation ◽

Acetyl Coa Carboxylase ◽

Malonyl Coa ◽

Amp Activated Protein Kinase

5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR) has previously been reported to be taken up into cells and phosphorylated to form ZMP, an analog of 5′-AMP. This study was designed to determine whether AICAR can activate AMP-activated protein kinase (AMPK) in skeletal muscle with consequent phosphorylation of acetyl-CoA carboxylase (ACC), decrease in malonyl-CoA, and increase in fatty acid oxidation. Rat hindlimbs were perfused with Krebs-Henseleit bicarbonate containing 4% bovine serum albumin, washed bovine red blood cells, 200 μU/ml insulin, and 10 mM glucose with or without AICAR (0.5–2.0 mM). Perfusion with medium containing AICAR was found to activate AMPK in skeletal muscle, inactivate ACC, and decrease malonyl-CoA. Hindlimbs perfused with 2 mM AICAR for 45 min exhibited a 2.8-fold increase in fatty acid oxidation and a significant increase in glucose uptake. No difference was observed in oxygen uptake in AICAR vs. control hindlimb. These results provide evidence that decreases in muscle content of malonyl-CoA can increase the rate of fatty acid oxidation.

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Metabolic response to an acute jump in cardiac workload: effects on malonyl-CoA, mechanical efficiency, and fatty acid oxidation

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00557.2007 ◽

2008 ◽

Vol 294 (2) ◽

pp. H954-H960 ◽

Cited By ~ 26

Author(s):

Lufang Zhou ◽

Hazel Huang ◽

Celvie L. Yuan ◽

Wendy Keung ◽

Gary D. Lopaschuk ◽

...

Keyword(s):

Fatty Acid ◽

Energy Expenditure ◽

Fatty Acid Oxidation ◽

Mechanical Efficiency ◽

Acid Oxidation ◽

Acetyl Coa Carboxylase ◽

Acetyl Coa ◽

Malonyl Coa ◽

High Workload ◽

Carnitine Palmitoyltransferase I

Inhibition of myocardial fatty acid oxidation can improve left ventricular (LV) mechanical efficiency by increasing LV power for a given rate of myocardial energy expenditure. This phenomenon has not been assessed at high workloads in nonischemic myocardium; therefore, we subjected in vivo pig hearts to a high workload for 5 min and assessed whether blocking mitochondrial fatty acid oxidation with the carnitine palmitoyltransferase-I inhibitor oxfenicine would improve LV mechanical efficiency. In addition, the cardiac content of malonyl-CoA (an endogenous inhibitor of carnitine palmitoyltransferase-I) and activity of acetyl-CoA carboxylase (which synthesizes malonyl-CoA) were assessed. Increased workload was induced by aortic constriction and dobutamine infusion, and LV efficiency was calculated from the LV pressure-volume loop and LV energy expenditure. In untreated pigs, the increase in LV power resulted in a 2.5-fold increase in fatty acid oxidation and cardiac malonyl-CoA content but did not affect the activation state of acetyl-CoA carboxylase. The activation state of the acetyl-CoA carboxylase inhibitory kinase AMP-activated protein kinase decreased by 40% with increased cardiac workload. Pretreatment with oxfenicine inhibited fatty acid oxidation by 75% and had no effect on cardiac energy expenditure but significantly increased LV power and LV efficiency (37 ± 5% vs. 26 ± 5%, P < 0.05) at high workload. In conclusion, 1) myocardial fatty acid oxidation increases with a short-term increase in cardiac workload, despite an increase in malonyl-CoA concentration, and 2) inhibition of fatty acid oxidation improves LV mechanical efficiency by increasing LV power without affecting cardiac energy expenditure.

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