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Yu Sam Kim - One of the best experts on this subject based on the ideXlab platform.
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Mass Spectrometric Identification of K210 Essential for Rat Malonyl-CoA Decarboxylase Catalysis
Journal of proteome research, 2006Co-Authors: Hyung Wook Nam, Gha Young Lee, Yu Sam KimAbstract:Proteomic technology provides useful tools to detect protein modification sites in vivo and in vitro. In this work, we applied proteomics to identify an essential amino acid residue involved in Malonyl-CoA Decarboxylase (MCD) catalysis. A reaction with acetic anhydride and MCD, under mild conditions without acetyl CoA as a substrate, resulted in the acetylation of six lysyl residues, K210, K58, K167, K316, K388, and K444. When acetyl CoA was added to the reaction, K210 was protected from acetylation, indicating a potential role for this residue in catalysis. In addition, K210 was the only lysyl residue, out of six, that was not endogenously acetylated. Because K210, K308, and K388 are conserved across species, they were site-specifically mutated to methionine which is size-wise similar to lysine but not protonated. The K308M and K388M MCD mutants retained 60% of their enzyme activities, whereas the K210M mutant was completely inactive. These results strongly suggest that K210 is an essential residue in ra...
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Peroxisomal-proliferator-activated receptor alpha activates transcription of the rat hepatic Malonyl-CoA Decarboxylase gene: a key regulation of Malonyl-CoA level.
Biochemical Journal, 2004Co-Authors: Gha Young Lee, Zheng-shan Zhao, Bong Soo Cha, Nam Hee Kim, Yu Sam KimAbstract:MCD (Malonyl-CoA Decarboxylase), which catalyses decarboxylation of Malonyl-CoA, is known to play an important role in the regulation of Malonyl-CoA concentration. Recently, it has been observed that the expression of MCD is significantly decreased in the hearts of the PPARalpha (peroxisome-proliferator-activated receptor alpha) (-/-) mice, where the rate of fatty-acid oxidation is decreased by the increased Malonyl-CoA level [Campbell, Kozak, Wagner, Altarejos, Dyck, Belke, Severson, Kelly and Lopaschuk (2002) J. Biol. Chem. 277, 4098-4103]. This suggests that MCD may be transcriptionally regulated by PPARalpha. To investigate whether PPARalpha is truly responsible for transcriptional regulation of the rat MCD gene, transient reporter assay was performed in CV-1 cells. The promoter activity was increased by 17-fold in CV-1 cells co-transfected with PPARalpha/retinoid X receptor alpha expression plasmid. In sequence analysis of the promoter region, three putative PPREs (PPAR response elements) were identified, and promoter deletion analysis showed that PPRE2 and PPRE3 were functional. Electrophoretic mobility-shift assays revealed that PPARalpha/retinoid X receptor alpha heterodimer indeed bound to the two PPREs, and the binding specificity of PPARalpha on PPRE was also confirmed by experiments with mutated oligonucleotides. These results indicate that the elements behaved as a responsive site to PPARalpha activation. MCD mRNA levels in WY14643-treated rat hepatoma cells as well as in the liver of fenofibrate-fed Otsuka Long-Evans Tokushima fatty rats were also found to be increased, suggesting that PPARalpha can activate the rat hepatic MCD transcription by binding to the PPREs in the promoter. We propose that MCD performs an important role in understanding the regulatory mechanism between activated PPARalpha and fatty-acid oxidation by altering the Malonyl-CoA concentration.
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Crystallization and preliminary X-ray crystallographic analysis of Malonyl-CoA Decarboxylase from Rhizobium leguminosarum bv. trifolii.
Acta Crystallographica Section D Biological Crystallography, 2002Co-Authors: Jin-seok Jung, Dong-jin Baek, Ga-young Lee, Yu Sam KimAbstract:Malonyl-CoA Decarboxylase (MCD), which catalyzes the conversion of Malonyl-CoA to acetyl-CoA, is an evolutionarily distinct and highly conserved enzyme. MCD does not share sequence homology with other known Decarboxylases, while the enzymes from different species exhibit at least >30% sequence identity to each other. In order to provide a canonical structure of the enzyme for detailed study of its structure-function relationship, the MCD of Rhizobium leguminosarum bv. trifolii was overexpressed and crystallized. The crystals belong to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 133.45, b = 127.10, c = 66.37 A. The asymmetric unit is likely to contain two molecules of MCD (molecular weight of 51 418 Da), with a crystal Volume per protein weight (V(M)) of 2.69 A(3) Da(-1) and a solvent content of about 54.3% by Volume. A native data set to 3.0 A resolution was obtained using a rotating-anode X-ray generator.
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Genomic organization and characterization of the promoter of rat Malonyl-CoA Decarboxylase gene.
Biochimica et biophysica acta, 2002Co-Authors: Gha Young Lee, Jin Won Cho, Hyun Chul Lee, Yu Sam KimAbstract:Abstract Malonyl-CoA Decarboxylase (MCD) catalyzes the decarboxylation of Malonyl-CoA, an elongating agent for fatty acid synthesis and also known as a fuel-sensing mediator. In order to elucidate the genome organization, we isolated a 2020 bp rat MCD cDNA from rat brain cDNA library and isolated the corresponding rat genomic clones from the rat genomic PAC library. Sequencing and comparison of these clones showed that the MCD genome consists of five exons and four introns spanning approximately 17 kb. The proximal upstream region is GC-rich, lacks a TATA box, and contains a variety of putative transcriptional regulatory elements within 2 kb. A major transcriptional initiation site was identified by a primer extension at a site 157 nucleotides upstream of the translational initiation site. To investigate the transcriptional regulation of MCD, a series of 5′-deletion constructs of the 5′-flanking region were generated and cloned upstream from the luciferase reporter gene. By comparing promoter activity in CV-1 cells, we suggest that an area of −15 bp 5′ from the first exon acted as a basal promoter for MCD and that there are positive cis -regulatory elements in the region from −55 to −325 bp and negative regulator elements in the region −1380 to −2240 bp.
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Rat Malonyl-CoA Decarboxylase; cloning, expression in E. coli and its biochemical characterization.
Journal of biochemistry and molecular biology, 2002Co-Authors: Gha Young Lee, Young Yil Bahk, Yu Sam KimAbstract:Malonyl-CoA Decarboxylase (E.C.4.1.1.9) catalyses the conversion of Malonyl-CoA to acetyl-CoA. Although the metabolic mle of this enzyme has not been fully defined, it has been reported that its deficiency is associated with mild mental retardation, seizures, hypotonia, cadiomyopathy, developmental delay, vomiting, hypoglycemia, metabolic acidosis, and malonic aciduria. Here, we isolated a cDNA clone for malonyl CoA Decarboxylase from a rat brain cDNA library, expressed it in E. coli, and characterized its biochemical properties. The full-length cDNA contained a single open-reading frame that encoded 491 amino acid residues with a calculated molecular weight of 54, 762 Da. Its deduced amino acid sequence revealed a 65.6% identity to that from the goose uropigial gland. The sequence of the first 38 amino acids represents a putative mitochondrial targeting sequence, and the last 3 amino acid sequences (SKL) represent peroxisomal targeting anes. The expression of malanyl CoA Decarboxylase was observed over a wide range of tissues as a single transcript of 2.0 kb in size. The recombinant protein that was expressed in E. coli was used to characterize the biochemical properties, which showed a typical Michaelis-Menten substrate saturation pattern. The K_m and V_(max) were calculated to be 68 μM and 42.6 μmol/min/mg, respectively.
Marc Prentki - One of the best experts on this subject based on the ideXlab platform.
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Malonyl-CoA Decarboxylase is present in the cytosolic, mitochondrial and peroxisomal compartments of rat hepatocytes.
FEBS letters, 2005Co-Authors: Erik Joly, Moise Bendayan, Raphaël Roduit, Asish K. Saha, Neil B. Ruderman, Marc PrentkiAbstract:A role for cytosolic Malonyl-CoA Decarboxylase (MCD) as a regulator of fatty acid oxidation has been postulated. However, there is no direct evidence that MCD is present in the cytosol. To address this issue, we performed cell fractionation and electron microscopic colloidal gold studies of rat liver to determine the location and activity of MCD. By both methods, substantial amounts of MCD protein and activity were found in the cytosol, mitochondria and peroxisomes, the latter with the highest specific activity. MCD species with different electrophoretic mobility were observed in the three fractions. The data demonstrate that active MCD is present in the cytosol, mitochondria and peroxisomes of rat liver, consistent with the view that MCD participates in the regulation of cytosolic Malonyl-CoA levels and of hepatic fatty acid oxidation.
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A Role for Hypothalamic Malonyl-CoA in the Control of Food Intake
The Journal of biological chemistry, 2005Co-Authors: Yun Dai, Marc Prentki, Shigeru Chohnan, M. Daniel LaneAbstract:The cellular level of Malonyl-CoA, an intermediate in fatty acid biosynthesis, depends on its rate of synthesis catalyzed by acetyl-CoA carboxylase relative to its rate of utilization and degradation catalyzed by fatty acid synthase and Malonyl-CoA Decarboxylase, respectively. Recent evidence suggests that hypothalamic Malonyl-CoA functions in the regulation of feeding behavior by altering the expression of key orexigenic and anorexigenic neuropeptides. Here we report that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), a 5'-AMP kinase activator, rapidly lowers Malonyl-CoA both in GT1-7 hypothalamic neurons and in the hypothalami of mice. These effects correlate closely with the phosphorylation of acetyl-CoA carboxylase, an established target of AMP kinase. Intracerebroventricular (i.c.v.) administration of AICAR rapidly lowers hypothalamic [Malonyl-CoA] and increases food intake. Expression of an adenoviral cytosolic Malonyl-CoA Decarboxylase vector (Ad-cMCD) in hypothalamic GT1-7 cells decreases Malonyl-CoA. When delivered by bilateral stereotaxic injection into the ventral hypothalamus (encompassing the arcuate nucleus) of mice, Ad-cMCD increases food intake and body weight. Ad-MCD delivered into the ventral hypothalamus also reverses the rapid suppression of food intake caused by i.c.v.-administered C75, a fatty acid synthase inhibitor that increases hypothalamic [Malonyl-CoA]. Taken together these findings implicate Malonyl-CoA in the hypothalamic regulation of feeding behavior.
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Coordinate Regulation of Malonyl-CoA Decarboxylase,sn-Glycerol-3-phosphate Acyltransferase, and Acetyl-CoA Carboxylase by AMP-activated Protein Kinase in Rat Tissues in Response to Exercise
The Journal of biological chemistry, 2002Co-Authors: Haejoe Park, Neil B. Ruderman, Marc Prentki, Virendar K. Kaushik, Scarlet Constant, Ewa Przybytkowski, Asish K. SahaAbstract:Abstract Changes in the concentration of Malonyl-CoA in many tissues have been related to alterations in the activity of acetyl-CoA carboxylase (ACC), the rate-limiting enzyme in its formation. In contrast, little is known about the physiological role of Malonyl-CoA Decarboxylase (MCD), an enzyme responsible for Malonyl-CoA catabolism. In this study, we examined the effects of voluntary exercise on MCD activity in rat liver, skeletal muscle, and adipose tissue. In addition, the activity ofsn-glycerol-3-phosphate acyltransferase (GPAT), which like MCD and ACC can be regulated by AMP-activated protein kinase (AMPK), was assayed. Thirty min after the completion of a treadmill run, MCD activity was increased ∼2-fold, Malonyl-CoA levels were reduced, and ACC and GPAT activities were diminished by 50% in muscle and liver. These events appeared to be mediated via activation of AMPK since: 1) AMPK activity was concurrently increased by exercise in both tissues; 2) similar findings were observed after the injection of 5-amino 4 imidazole carboxamide, an AMPK activator; 3) changes in the activity of GPAT and ACC paralleled that of MCD; and 4) the increase in MCD activity in muscle was reversed in vitro by incubating immunoprecipitated enzyme from the exercised muscle with protein phosphatase 2A, and it was reproduced by incubating immunopurified MCD from resting muscle with purified AMPK. An unexpected finding was that exercise caused similar changes in the activities of ACC, MCD, GPAT, and AMPK and the concentration of Malonyl-CoA in adipose tissue. In conclusion: MCD, GPAT, and ACC are coordinately regulated by AMPK in liver and adipose tissue in response to exercise, and except for GPAT, also in muscle. The results suggest that AMPK activation plays a major role in regulating lipid metabolism in many cells following exercise. They also suggest that in each of them, it acts to increase fatty acid oxidation and decrease its esterification.
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Characterization of rat liver Malonyl-CoA Decarboxylase and the study of its role in regulating fatty acid metabolism.
Biochemical Journal, 2000Co-Authors: Jason R.b. Dyck, Nicolas Voilley, Luc G. Berthiaume, Panakkezhum D. Thomas, Paul F. Kantor, Amy Barr, Rick L. Barr, Dyal Singh, Teresa A. Hopkins, Marc PrentkiAbstract:In the liver, Malonyl-CoA is central to many cellular processes, including both fatty acid biosynthesis and oxidation. Malonyl-CoA Decarboxylase (MCD) is involved in the control of cellular Malonyl-CoA levels, and functions to decarboxylate Malonyl-CoA to acetyl-CoA. MCD may play an essential role in regulating energy utilization in the liver by regulating Malonyl-CoA levels in response to various nutritional or pathological states. The purpose of the present study was to investigate the role of liver MCD in the regulation of fatty acid oxidation in situations where lipid metabolism is altered. A single MCD enzyme of molecular mass 50.7 kDa was purified from rat liver using a sequential column chromatography procedure and the cDNA was subsequently cloned and sequenced. The liver MCD cDNA was identical to rat pancreatic beta-cell MCD cDNA, and contained two potential translational start sites, producing proteins of 50.7 kDa and 54.7 kDa. Western blot analysis using polyclonal antibodies generated against rat liver MCD showed that the 50.7 kDa isoform of MCD is most abundant in heart and liver, and of relatively low abundance in skeletal muscle (despite elevated MCD transcript levels in skeletal muscle). Tissue distribution experiments demonstrated that the pancreas is the only rat tissue so far identified that contains both the 50.7 kDa and 54. 7 kDa isoforms of MCD. In addition, transfection of the full-length rat liver MCD cDNA into COS cells produced two isoforms of MCD. This indicated either that both initiating methionines are functionally active, generating two proteins, or that the 54.7 kDa isoform is the only MCD protein translated and removal of the putative mitochondrial targeting pre-sequence generates a protein of approx. 50.7 kDa in size. To address this, we transiently transfected a mutated MCD expression plasmid (second ATG to GCG) into COS-7 cells and performed Western blot analysis using our anti-MCD antibody. Western blot analysis revealed that two isoforms of MCD were still present, demonstrating that the second ATG may not be responsible for translation of the 50.7 kDa isoform of MCD. These data also suggest that the smaller isoform of MCD may originate from intracellular processing. To ascertain the functional role of the 50. 7 kDa isoform of rat liver MCD, we measured liver MCD activity and expression in rats subjected to conditions which are known to alter fatty acid metabolism. The activity of MCD was significantly elevated under conditions in which hepatic fatty acid oxidation is known to increase, such as streptozotocin-induced diabetes or following a 48 h fast. A 2-fold increase in expression was observed in the streptozotocin-diabetic rats compared with control rats. In addition, MCD activity was shown to be enhanced by alkaline phosphatase treatment, suggesting phosphorylation-related control of the enzyme. Taken together, our data demonstrate that rat liver expresses a 50.7 kDa form of MCD which does not originate from the second methionine of the cDNA sequence. This MCD is regulated by at least two mechanisms (only one of which is phosphorylation), and its activity and expression are increased under conditions where fatty acid oxidation increases.
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Activation of Malonyl-CoA Decarboxylase in rat skeletal muscle by contraction and the AMP-activated protein kinase activator 5-aminoimidazole-4-carboxamide-1-beta -D-ribofuranoside.
The Journal of biological chemistry, 2000Co-Authors: Asish K. Saha, Raphaël Roduit, Marc Prentki, Alexandria J. Schwarsin, Frédéric Massé, Virendar K. Kaushik, Keith Tornheim, Neil B. RudermanAbstract:Alterations in the concentration of Malonyl-CoA, an inhibitor of carnitine palmitoyltransferase I, have been linked to the regulation of fatty acid oxidation in skeletal muscle. During contraction decreases in muscle Malonyl-CoA concentration have been related to activation of AMP-activated protein kinase (AMPK), which phosphorylates and inhibits acetyl-CoA carboxylase (ACC), the rate-limiting enzyme in Malonyl-CoA formation. We report here that the activity of Malonyl-CoA Decarboxylase (MCD) is increased in contracting muscle. Using either immunopurified enzyme or enzyme partially purified by (NH(4))(2)SO(4) precipitation, 2-3-fold increases in the V(max) of MCD and a 40% decrease in its K(m) for Malonyl-CoA (190 versus 119 micrometer) were observed in rat gastrocnemius muscle after 5 min of contraction, induced by electrical stimulation of the sciatic nerve. The increase in MCD activity was markedly diminished when immunopurified enzyme was treated with protein phosphatase 2A or when phosphatase inhibitors were omitted from the homogenizing solution and assay mixture. Incubation of extensor digitorum longus muscle for 1 h with 2 mm 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside, a cell-permeable activator of AMPK, increased MCD activity 2-fold. Here, too, addition of protein phosphatase 2A to the immunopellets reversed the increase of MCD activity. The results strongly suggest that activation of AMPK during muscle contraction leads to phosphorylation of MCD and an increase in its activity. They also suggest a dual control of Malonyl-CoA concentration by ACC and MCD, via AMPK, during exercise.
Gary D. Lopaschuk - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of Malonyl-CoA Decarboxylase reduces the inflammatory response associated with insulin resistance.
American journal of physiology. Endocrinology and metabolism, 2012Co-Authors: Victor Samokhvalov, John R. Ussher, Natasha Fillmore, Ian K.g. Armstrong, Wendy Keung, Daniel Moroz, David G. Lopaschuk, John M. Seubert, Gary D. LopaschukAbstract:We previously showed that genetic inactivation of Malonyl-CoA Decarboxylase (MCD), which regulates fatty acid oxidation, protects mice against high-fat diet-induced insulin resistance. Development of insulin resistance has been associated with activation of the inflammatory response. Therefore, we hypothesized that the protective effect of MCD inhibition might be caused by a favorable effect on the inflammatory response. We examined if pharmacological inhibition of MCD protects neonatal cardiomyocytes and peritoneal macrophages against inflammatory-induced metabolic perturbations. Cardiomyocytes and macrophages were treated with LPS to induce an inflammatory response, in the presence or absence of an MCD inhibitor (CBM-301106, 10 μM). Inhibition of MCD attenuated the LPS-induced inflammatory response in cardiomyocytes and macrophages. MCD inhibition also prevented LPS impairment of insulin-stimulated glucose uptake in cardiomyocytes and increased phosphorylation of Akt. Additionally, inhibition of MCD strongly diminished LPS-induced activation of palmitate oxidation. We also found that treatment with an MCD inhibitor prevented LPS-induced collapse of total cellular antioxidant capacity. Interestingly, treatment with LPS or an MCD inhibitor did not alter intracellular triacylglycerol content. Furthermore, inhibition of MCD prevented LPS-induced increases in the level of ceramide in cardiomyocytes and macrophages while also ameliorating LPS-initiated decreases in PPAR binding. This suggests that the anti-inflammatory effect of MCD inhibition is mediated via accumulation of long-chain acyl-CoA, which in turn stimulates PPAR binding. Our results also demonstrate that pharmacological inhibition of MCD is a novel and promising approach to treat insulin resistance and its associated metabolic complications.
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Fatty acid oxidation and Malonyl-CoA Decarboxylase in the vascular remodeling of pulmonary hypertension.
Science translational medicine, 2010Co-Authors: Gopinath Sutendra, Gary D. Lopaschuk, Jason R.b. Dyck, Sébastien Bonnet, Gaël Y. Rochefort, Alois Haromy, Karalyn D. Folmes, Evangelos D. MichelakisAbstract:Pulmonary arterial hypertension is caused by excessive growth of vascular cells that eventually obliterate the pulmonary arterial lumen, causing right ventricular failure and premature death. Despite some available treatments, its prognosis remains poor, and the cause of the vascular remodeling remains unknown. The vascular smooth muscle cells that proliferate during pulmonary arterial hypertension are characterized by mitochondrial hyperpolarization, activation of the transcription factor NFAT (nuclear factor of activated T cells), and down-regulation of the voltage-gated potassium channel Kv1.5, all of which suppress apoptosis. We found that mice lacking the gene for the metabolic enzyme malonyl–coenzyme A (CoA) Decarboxylase (MCD) do not show pulmonary vasoconstriction during exposure to acute hypoxia and do not develop pulmonary arterial hypertension during chronic hypoxia but have an otherwise normal phenotype. The lack of MCD results in an inhibition of fatty acid oxidation, which in turn promotes glucose oxidation and prevents the shift in metabolism toward glycolysis in the vascular media, which drives the development of pulmonary arterial hypertension in wild-type mice. Clinically used metabolic modulators that mimic the lack of MCD and its metabolic effects normalize the mitochondrial-NFAT-Kv1.5 defects and the resistance to apoptosis in the proliferated smooth muscle cells, reversing the pulmonary hypertension induced by hypoxia or monocrotaline in mice and rats, respectively. This study of fatty acid oxidation and MCD identifies a critical role for metabolism in both the normal pulmonary circulation (hypoxic pulmonary vasoconstriction) and pulmonary hypertension, pointing to several potential therapeutic targets for the treatment of this deadly disease.
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Insulin-Stimulated Cardiac Glucose Oxidation Is Increased in High-Fat Diet–Induced Obese Mice Lacking Malonyl CoA Decarboxylase
Diabetes, 2009Co-Authors: John R. Ussher, Timothy R. Koves, Jason R.b. Dyck, Liyan Zhang, Jagdip S. Jaswal, Olga Ilkayeva, Deborah M. Muoio, Gary D. LopaschukAbstract:OBJECTIVE Whereas an impaired ability to oxidize fatty acids is thought to contribute to intracellular lipid accumulation, insulin resistance, and cardiac dysfunction, high rates of fatty acid oxidation could also impair glucose metabolism and function. We therefore determined the effects of diet-induced obesity (DIO) in wild-type (WT) mice and mice deficient for malonyl CoA Decarboxylase (MCD −/− ; an enzyme promoting mitochondrial fatty acid oxidation) on insulin-sensitive cardiac glucose oxidation. RESEARCH DESIGN AND METHODS WT and MCD −/− mice were fed a low- or high-fat diet for 12 weeks, and intramyocardial lipid metabolite accumulation was assessed. A parallel feeding study was performed to assess myocardial function and energy metabolism (nanomoles per gram of dry weight per minute) in isolated working hearts (+/– insulin). RESULTS DIO markedly reduced insulin-stimulated glucose oxidation compared with low fat–fed WT mice (167 ± 31 vs. 734 ± 125; P −/− mice subjected to DIO displayed a more robust insulin-stimulated glucose oxidation (554 ± 82 vs. 167 ± 31; P −/− mice had long-chain acyl CoAs similar to those of WT mice subjected to DIO but had increased triacylglycerol levels (10.92 ± 3.72 vs. 3.29 ± 0.62 μmol/g wet wt; P CONCLUSIONS DIO does not impair cardiac fatty acid oxidation or function, and there exists disassociation between myocardial lipid accumulation and insulin sensitivity. Our results suggest that MCD deficiency is not detrimental to the heart in obesity.
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Malonyl-CoA Decarboxylase Inhibition as a Novel Approach to Treat Ischemic Heart Disease
Cardiovascular drugs and therapy, 2006Co-Authors: Gary D. Lopaschuk, William C. StanleyAbstract:Introduction During and following cardiac ischemia the levels of circulating fatty acids are elevated, resulting in fatty acid oxidation dominating as a source of oxidative metabolism at the expense of pyruvate oxidation. A decrease in the levels of myocardial Malonyl-CoA (an endogenous inhibitor of mitochondrial fatty acid uptake) contributes to these high fatty acid oxidation rates. Low pyruvate oxidation rates during and following ischemia results in the accumulation of metabolic byproducts (lactate and protons) that leads to impaired cardiac function, decreased cardiac efficiency, and increased myocardial tissue injury.
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Malonyl-CoA Decarboxylase Inhibition as a Novel Approach to Treat Ischemic Heart Disease
Cardiovascular Drugs and Therapy, 2006Co-Authors: Gary D. Lopaschuk, William C. StanleyAbstract:Introduction During and following cardiac ischemia the levels of circulating fatty acids are elevated, resulting in fatty acid oxidation dominating as a source of oxidative metabolism at the expense of pyruvate oxidation. A decrease in the levels of myocardial Malonyl-CoA (an endogenous inhibitor of mitochondrial fatty acid uptake) contributes to these high fatty acid oxidation rates. Low pyruvate oxidation rates during and following ischemia results in the accumulation of metabolic byproducts (lactate and protons) that leads to impaired cardiac function, decreased cardiac efficiency, and increased myocardial tissue injury. Methodology One approach to increasing pyrvuate oxidation during and following ischemia is to inhibit fatty acid oxidation, which results in an improvement of both cardiac function and cardiac efficiency. A novel approach to decreasing fatty acid oxidation and increasing pyrvuate oxidation is to increase myocardial levels of Malonyl-CoA. This can be achieved by pharmacologically inhibiting Malonyl-CoA Decarboxylase (MCD), the principal enzyme involved in the degradation of cardiac Malonyl-CoA. Results Studies with either genetic deletion of MCD in the mouse or with novel MCD inhibitors show that decreased MCD activity increases cardiac Malonyl-CoA, resulting in an inhibition of fatty acid oxidation and a stimulation of pyrvuate oxidation. Conclusion The beneficial effects of MCD inhibition on cardiac function and cardiac efficiency suggest that this approach could be an effective means to treat ischemic heart disease.
Jason R.b. Dyck - One of the best experts on this subject based on the ideXlab platform.
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Fatty acid oxidation and Malonyl-CoA Decarboxylase in the vascular remodeling of pulmonary hypertension.
Science translational medicine, 2010Co-Authors: Gopinath Sutendra, Gary D. Lopaschuk, Jason R.b. Dyck, Sébastien Bonnet, Gaël Y. Rochefort, Alois Haromy, Karalyn D. Folmes, Evangelos D. MichelakisAbstract:Pulmonary arterial hypertension is caused by excessive growth of vascular cells that eventually obliterate the pulmonary arterial lumen, causing right ventricular failure and premature death. Despite some available treatments, its prognosis remains poor, and the cause of the vascular remodeling remains unknown. The vascular smooth muscle cells that proliferate during pulmonary arterial hypertension are characterized by mitochondrial hyperpolarization, activation of the transcription factor NFAT (nuclear factor of activated T cells), and down-regulation of the voltage-gated potassium channel Kv1.5, all of which suppress apoptosis. We found that mice lacking the gene for the metabolic enzyme malonyl–coenzyme A (CoA) Decarboxylase (MCD) do not show pulmonary vasoconstriction during exposure to acute hypoxia and do not develop pulmonary arterial hypertension during chronic hypoxia but have an otherwise normal phenotype. The lack of MCD results in an inhibition of fatty acid oxidation, which in turn promotes glucose oxidation and prevents the shift in metabolism toward glycolysis in the vascular media, which drives the development of pulmonary arterial hypertension in wild-type mice. Clinically used metabolic modulators that mimic the lack of MCD and its metabolic effects normalize the mitochondrial-NFAT-Kv1.5 defects and the resistance to apoptosis in the proliferated smooth muscle cells, reversing the pulmonary hypertension induced by hypoxia or monocrotaline in mice and rats, respectively. This study of fatty acid oxidation and MCD identifies a critical role for metabolism in both the normal pulmonary circulation (hypoxic pulmonary vasoconstriction) and pulmonary hypertension, pointing to several potential therapeutic targets for the treatment of this deadly disease.
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Insulin-Stimulated Cardiac Glucose Oxidation Is Increased in High-Fat Diet–Induced Obese Mice Lacking Malonyl CoA Decarboxylase
Diabetes, 2009Co-Authors: John R. Ussher, Timothy R. Koves, Jason R.b. Dyck, Liyan Zhang, Jagdip S. Jaswal, Olga Ilkayeva, Deborah M. Muoio, Gary D. LopaschukAbstract:OBJECTIVE Whereas an impaired ability to oxidize fatty acids is thought to contribute to intracellular lipid accumulation, insulin resistance, and cardiac dysfunction, high rates of fatty acid oxidation could also impair glucose metabolism and function. We therefore determined the effects of diet-induced obesity (DIO) in wild-type (WT) mice and mice deficient for malonyl CoA Decarboxylase (MCD −/− ; an enzyme promoting mitochondrial fatty acid oxidation) on insulin-sensitive cardiac glucose oxidation. RESEARCH DESIGN AND METHODS WT and MCD −/− mice were fed a low- or high-fat diet for 12 weeks, and intramyocardial lipid metabolite accumulation was assessed. A parallel feeding study was performed to assess myocardial function and energy metabolism (nanomoles per gram of dry weight per minute) in isolated working hearts (+/– insulin). RESULTS DIO markedly reduced insulin-stimulated glucose oxidation compared with low fat–fed WT mice (167 ± 31 vs. 734 ± 125; P −/− mice subjected to DIO displayed a more robust insulin-stimulated glucose oxidation (554 ± 82 vs. 167 ± 31; P −/− mice had long-chain acyl CoAs similar to those of WT mice subjected to DIO but had increased triacylglycerol levels (10.92 ± 3.72 vs. 3.29 ± 0.62 μmol/g wet wt; P CONCLUSIONS DIO does not impair cardiac fatty acid oxidation or function, and there exists disassociation between myocardial lipid accumulation and insulin sensitivity. Our results suggest that MCD deficiency is not detrimental to the heart in obesity.
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Malonyl‐CoA Decarboxylase (MCD) is differentially regulated in subcellular compartments by 5′AMP‐activated protein kinase (AMPK)
European journal of biochemistry, 2004Co-Authors: Nandakumar Sambandam, Jason R.b. Dyck, Michael Steinmetz, Angel Chu, Judith Y. Altarejos, Gary D. LopaschukAbstract:Malonyl-CoA, a potent inhibitor of carnitine pamitoyl transferase-I (CPT-I), plays a pivotal role in fuel selection in cardiac muscle. Malonyl-CoA Decarboxylase (MCD) catalyzes the degradation of Malonyl-CoA, removes a potent allosteric inhibition on CPT-I and thereby increases fatty acid oxidation in the heart. Although MCD has several Ser/Thr phosphorylation sites, whether it is regulated by AMP-activated protein kinase (AMPK) has been controversial. We therefore overexpressed MCD (Ad.MCD) and constitutively active AMPK (Ad.CA-AMPK) in H9c2 cells, using an adenoviral gene delivery approach in order to examine if MCD is regulated by AMPK. Cells infected with Ad.CA-AMPK demonstrated a fourfold increase in AMPK activity as compared with control cells expressing green fluorescent protein (Ad.GFP). MCD activity increased 40- to 50-fold in Ad.MCD + Ad.GFP cells when compared with Ad.GFP control. Co-expressing AMPK with MCD further augmented MCD expression and activity in Ad.MCD + Ad.CA-AMPK cells compared with the Ad.MCD + Ad.GFP control. Subcellular fractionation further revealed that 54.7 kDa isoform of MCD expression was significantly higher in cytosolic fractions of Ad.MCD + Ad.CA-AMPK cells than of the Ad.MCD +Ad.GFP control. However, the MCD activities in cytosolic fractions were not different between the two groups. Interestingly, in the mitochondrial fractions, MCD activity significantly increased in Ad.MCD + Ad.CA-AMPK cells when compared with Ad.MCD + Ad.GFP cells. Using phosphoserine and phosphothreonine antibodies, no phosphorylation of MCD by AMPK was observed. The increase in MCD activity in mitochondria-rich fractions of Ad.MCD + Ad.CA-AMPK cells was accompanied by an increase in the level of the 50.7 kDa isoform of MCD protein in the mitochondria. This differential regulation of MCD expression and activity in the mitochondria by AMPK may potentially regulate Malonyl-CoA levels at sites nearby CPT-I on the mitochondria.
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Regulation of Malonyl-CoA concentration and turnover in the normal heart.
The Journal of biological chemistry, 2004Co-Authors: Aneta E. Reszko, Jie-fei Cheng, Gary D. Lopaschuk, Jason R.b. Dyck, Takhar Kasumov, Katherine R. Thomas, Kathryn A. Jobbins, Mireya Diaz, Christine Des Rosiers, William C. StanleyAbstract:The goal of this study was to test the relationship between Malonyl-CoA concentration and its turnover measured in isolated rat hearts perfused with NaH(13)CO(3). This turnover is a direct measurement of the flux of acetyl-CoA carboxylation in the intact heart. It also reflects the rate of Malonyl-CoA decarboxylation, i.e. the only known fate of Malonyl-CoA in the heart. Conditions were selected to result in stable Malonyl-CoA concentrations ranging from 1.5 to 5 nmol.g wet weight-(1). The Malonyl-CoA concentration was directly correlated with the turnover of Malonyl-CoA, ranging from 0.7 to 4.2 nmol.min(-) (1).g wet weight(-1) (slope = 0.98, r(2) = 0.94). The V(max) activities of acetyl-CoA carboxylase and of Malonyl-CoA Decarboxylase exceeded the rate of Malonyl-CoA turnover by 2 orders of magnitude and did not correlate with either concentration or turnover of Malonyl-CoA. However, conditions of perfusion that increased acetyl-CoA supply resulted in higher turnover and concentration, demonstrating that Malonyl-CoA turnover is regulated by the supply of acetyl-CoA. The only condition where the activity of Malonyl-CoA Decarboxylase regulated Malonyl-CoA kinetics was when the enzyme was pharmacologically inhibited, resulting in increased Malonyl-CoA concentration and decreased turnover. Our data show that, in the absence of enzyme inhibitors, the rate of acetyl-CoA carboxylation is the main determinant of the Malonyl-CoA concentration in the heart.
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A Role for Peroxisome Proliferator-activated Receptor α (PPARα) in the Control of Cardiac Malonyl-CoA Levels REDUCED FATTY ACID OXIDATION RATES AND INCREASED GLUCOSE OXIDATION RATES IN THE HEARTS OF MICE LACKING PPARα ARE ASSOCIATED WITH HIGHER CONCE
The Journal of biological chemistry, 2001Co-Authors: Fiona Margaret Campbell, Jason R.b. Dyck, Judith Y. Altarejos, Ray Kozak, Alese Wagner, Darrell D Belke, David L Severson, Daniel P. Kelly, Gary D. LopaschukAbstract:Peroxisome proliferator-activated receptor alpha (PPARalpha) is a nuclear receptor transcription factor that has an important role in controlling cardiac metabolic gene expression. We determined whether mice lacking PPARalpha (PPARalpha (-/-) mice) have alterations in cardiac energy metabolism. Rates of palmitate oxidation were significantly decreased in isolated working hearts from PPARalpha (-/-) hearts compared with hearts from age-matched wild type mice (PPARalpha (+/+) mice), (62 +/- 12 versus 154 +/- 65 nmol/g dry weight/min, respectively, p < 0.05). This was compensated for by significant increases in the rates of glucose oxidation and glycolysis. The decreased fatty acid oxidation in PPARalpha (-/-) hearts was associated with increased levels of cardiac Malonyl-CoA compared with PPARalpha (+/+) hearts (15.15 +/- 1.63 versus 7.37 +/- 1.31 nmol/g, dry weight, respectively, p < 0.05). Since Malonyl-CoA is an important regulator of cardiac fatty acid oxidation, we also determined if the enzymes that control Malonyl-CoA levels in the heart are under transcriptional control of PPARalpha. Expression of both mRNA and protein as well as the activity of Malonyl-CoA Decarboxylase, which degrades Malonyl-CoA, were significantly decreased in the PPARalpha (-/-) hearts. In contrast, the expression and activity of acetyl-CoA carboxylase, which synthesizes Malonyl-CoA and 5'-AMP-activated protein kinase, which regulates acetyl-CoA carboxylase, were not altered. Glucose transporter expression (GLUT1 and GLUT4) was not different between PPARalpha (-/-) and PPARalpha (+/+) hearts, suggesting that the increase in glycolysis and glucose oxidation in the PPARalpha null mice was not due to direct effects on glucose uptake but rather was occurring secondary to the decrease in fatty acid oxidation. This study demonstrates that PPARalpha is an important regulator of fatty acid oxidation in the heart and that this regulation of fatty acid oxidation may in part occur due to the transcriptional control of Malonyl-CoA Decarboxylase.
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Novel trifluoroacetophenone derivatives as Malonyl-CoA Decarboxylase inhibitors.
Bioorganic & medicinal chemistry letters, 2007Co-Authors: David Wallace, Jie-fei Cheng, Thomas Arrhenius, Masayuki Haramura, Alex M. NadzanAbstract:A series of trifluoroacetophenone derivatives were prepared and evaluated as Malonyl-CoA Decarboxylase (MCD) inhibitors. Some of the 'reverse amide' analogs were found to be potent inhibitors of MCD enzyme activity. The trifluoroacetyl group may interact with the MCD active site as the hydrate in a similar fashion to the hexafluoroisopropanol analogs reported previously. Adding electron-withdrawing groups to the phenyl ring stabilizes the hydrated species and enhances this interaction.
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Discovery of potent and orally available Malonyl-CoA Decarboxylase inhibitors as cardioprotective agents.
Journal of medicinal chemistry, 2006Co-Authors: Jie-fei Cheng, Yujin Huang, Richard Penuliar, Masahiro Nishimoto, Thomas Arrhenius, Larry Liu, Guang Yang, Eoin O'leary, Miguel Barbosa, Rick L. BarrAbstract:Discovery of 5-(1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)-4,5-dihydroisoxazole-3-carboxamides as a new class of malonyl-coenzyme A Decarboxylase (MCD) inhibitors is described. tert-Butyl 3-(5-(1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)-4,5-dihydroisoxazole-3-carboxamido)butanoate (5, CBM-301940) exhibited excellent potency and in vivo PK/ADME properties. It is the most powerful stimulant of glucose oxidation reported to date in isolated working rat hearts. Compound 5 improved the cardiac efficiency and function in a rat heart global ischemia/reperfusion model, suggesting MCD inhibitors may be useful for the treatment of ischemic heart diseases.
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Heteroaryl substituted bis-trifluoromethyl carbinols as Malonyl-CoA Decarboxylase inhibitors.
Bioorganic & medicinal chemistry letters, 2006Co-Authors: Jie-fei Cheng, Chi Ching Mak, Yujin Huang, Richard Penuliar, Masahiro Nishimoto, Lin Zhang, Mi Chen, David Wallace, Thomas Arrhenius, Donald ChuAbstract:A series of heteroaryl-substituted bis-trifluoromethyl carbinols were prepared and evaluated as Malonyl-CoA Decarboxylase (MCD) inhibitors. Some thiazole-based derivatives showed potent in vitro MCD inhibitory activities and significantly increased glucose oxidation rates in isolated working rat hearts.
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Synthesis and structure-activity relationship of small-molecule malonyl coenzyme A Decarboxylase inhibitors.
Journal of medicinal chemistry, 2006Co-Authors: Jie-fei Cheng, Chi Ching Mak, Mi Chen, David Wallace, Thomas Arrhenius, Masayuki Haramura, Bin Liu, Souvothy Tith, Sean Reily, Steven J. BrownAbstract:The discovery and structure−activity relationship of first-generation small-molecule Malonyl-CoA Decarboxylase (MCD; CoA = coenzyme A) inhibitors are reported. We demonstrated that MCD inhibitors increased Malonyl-CoA concentration in the isolated working rat hearts. Malonyl-CoA is a potent, endogenous, and allosteric inhibitor of carnitine palmitoyltransferase-I (CPT-I), a key enzyme for mitochondrial fatty acid oxidation. As a result of the increase in Malonyl-CoA levels, fatty acid oxidation rates were decreased and the glucose oxidation rates were significantly increased. Demonstration of in vivo efficacy of methyl 5-(N-(4-(1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)phenyl)morpholine-4-carboxamido)pentanoate (6u) in a pig ischemia model indicated that MCD inhibitors may be useful for treating ischemic heart diseases.
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Design and synthesis of heterocyclic Malonyl-CoA Decarboxylase inhibitors.
Bioorganic & medicinal chemistry letters, 2005Co-Authors: Jie-fei Cheng, Mi Chen, Thomas Arrhenius, Bin Liu, Zheng Hou, Alex M. NadzanAbstract:We have previously reported the discovery of small molecule inhibitors of Malonyl-CoA Decarboxylase (MCD) as novel metabolic modulators, which inhibited fatty acid oxidation and consequently increased the glucose oxidation rates in the isolated working rat hearts. MCD inhibitors were also shown to improve cardiac efficiency in rat and pig demand-induced ischemic models through the mechanism-based modulation of energy metabolism. Herein, we describe the design and synthesis of a series of novel heterocyclic MCD inhibitors with a preference for substituted imidazole and isoxazole.