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Metabolic Alterations in Muscle Associated with Obesity
Published in Emmanuel Opara, NUTRITION and DIABETES, 2005
John P. Thyfault, G. Lynis Dohm
A clear association can be linked between metabolic inflexibility and a defect in lipid oxidation measured with obesity. In normal conditions, an increase in dietary fat or plasma lipids is met with adaptations that increase lipid metabolism in skeletal muscle. In rodent studies, in which plasma fatty-acids levels are significantly increased (fasting, high-fat feedings, streptozotocin-induced diabetes) there is an equivalent increase in the expression and activity of lipid-metabolizing enzymes in skeletal muscle, including malonyl-CoA decarboxylase, CPT-1, β-HAD, pyruvate dehydrogenase kinase 4, and FAT/CD36.72,108 In healthy, nonobese humans, five days of a high-fat diet increased lipid oxidation (measured by RQ) during submaximal exercise and increased genes important for fat oxidation, including FAT/CD36, FABPpm, β-HAD, and CPT-1.18 In another study, nonobese subjects increased total daily fat oxidation (measured in indirect calorimetry chamber) after seven days of a high-fat diet.96 These data demonstrate that nonobese individuals can increase lipid oxidation when needed. Conversely, it appears that obese individuals lack an ability to increase lipid oxidation following dietary manipulation. Astrup et al.5 compared lipid oxidation between previously obese and lean women following three days of a high fat-diet (50 percent fat). Lean women adjusted rates of fat oxidation to the diet. However, previously obese (post weight loss) women could not increase fat oxidation, resulting in positive fat balance and storage.
MUSCLE METABOLISM
Published in David M. Gibson, Robert A. Harris, Metabolic Regulation in Mammals, 2001
David M. Gibson, Robert A. Harris
Excess fuel available in the fed state in the form of glucose and fatty acids tills the mitochondrial matrix space with citric acid cycle intermediates. Part of the citrate escapes to the cytoplasm where it serves as a signal that the amount of glucose and fatty acids available exceeds the immediate needs ol the cell lor energy. Citrate is idealiv suited to function as an "excess fuel" signal since it inhibits the catabolism of both glucose and fatty acids. Citrate restrains glucose catabolism through direct inhibition of 6-phosphofructo-1-kinase and indirectly through lowering of fructose 2,6-bisphosphate by inhibition of 6-phosphofructo-2-kinase. The increase in glucose 6-phosphate, caused by inhibition of 6-phosphofructo-1-kinase, promotes gly cogen synthesis by a positive allosteric effect on glvcogen synthase. Citrate also imposes restraint upon the oxidation of fattv acids by indirectly inhibiting carnitine palmitoyltransferase I. This is accomplished through its activation ofacetyl-CoA carboxylase, which produces malonyl-CoA, a negative allosteric effector for carnitine palmitoyltransferase I. Citrate's effect on acetyl-CoA carboxylase is dependent upon insulin-signaled dcphosphorylation of acetyl CoA carboxylase, an action most likely mediated by activation of a phosphopro-tein phosphatase (Figure 6.1 3). Another player in this scheme is malonyl-CoA decarboxylase (MCD), the importance of which is only now In-ginning to emerge from the work of a number of investigators (figure 6.10). By opposing the reaction catalyzed by acetyl-CoA carboxylase, this enzy me functions to decrease malonyl-CoA concentrations (figure 6.14). Like acetyl-CoA carboxylase, malonyl-CoA decarboxylase is subject tocovalcnt modification, but contrary to acetyl-CoA carboxylase, malonyl-CoA decarboxylase is active phosphorvlatcd and inactive when dcphosphorylatcd. Thus, in the fed state, when acctyl-CoA carboxylase, malonyl-CoA decarboxylase and most other metabolic enzymes are dcphosphorylatcd, malonvl-CoA decarboxylase is inactive and therefore docs not destroy malonyl-CoA produced by acetyl-CoA carboxylase.
Effect of aerobic training with silymarin consumption on glycemic indices and liver enzymes in men with type 2 diabetes
Published in Archives of Physiology and Biochemistry, 2023
Keyvan Ghalandari, Mojtaba Shabani, Ali Khajehlandi, Amin Mohammadi
Also, exercise by increasing glucose carriers (GLUT4) inside muscle cells and insulin receptor substrates (IRS) and increasing muscle mass, rises body responsiveness to insulin and increases insulin sensitivity (over 75% glucose uptake is induced by insulin stimulation related to muscle tissue. Exercise activity by increasing fatty acid oxidation inhibits its accumulation in the muscle cell (Hosseini et al.2019). Long-term AT with the production of heat shock protein 70 inhibits AST and ALT activities; in addition, since there is a negative association between insulin sensitivity and fat accumulation in the liver tissue, exercise activity appears to inhibit the synthesis of fats in the liver and activate the AMP-activated protein kinase (AMPK) pathway by increasing fat oxidation. AMPK then inhibits lipid synthesis in the liver which is carried out by inactivating acetyl-CoA carboxylase, activating malonyl-CoA decarboxylase, and inhibiting the expression of lipogenic enzymes, including acetyl-CoA carboxylase and fatty acid synthetase (Kim et al.2019).
Personalized Nutrition: Translating the Science of NutriGenomics Into Practice: Proceedings From the 2018 American College of Nutrition Meeting
Published in Journal of the American College of Nutrition, 2019
Okezie I Aruoma, Sharon Hausman-Cohen, Jessica Pizano, Michael A. Schmidt, Deanna M. Minich, Yael Joffe, Sebastian Brandhorst, Simon J. Evans, David M. Brady
Since MTHFR requires FAD as a co-factor, the organic acid glutaric acid which increases with riboflavin insufficiency may be used to validate. Chronically high levels of glutaric acid are suggested to associated with at least three inborn errors of metabolism, including glutaric aciduria type I, malonyl-CoA decarboxylase deficiency, and glutaric aciduria type III. Glutaric aciduria type I (glutaric acidemia type I, glutaryl-CoA dehydrogenase deficiency, GA1, or GAT1) is an inherited disorder in which the body is unable to completely break down the amino acids lysine, hydroxylysine, and tryptophan due to a deficiency of mitochondrial glutaryl-CoA dehydrogenase. Excessive levels of their intermediate breakdown products (including glutaric acid, glutaryl-CoA, 3-hydroxyglutaric acid, and glutaconic acid) may accumulate and can cause damage to the brain (and also other organs; https://pubchem.ncbi.nlm.nih.gov/compound/glutaric_acid).
Metabolomic profiling for the identification of novel diagnostic markers and therapeutic targets in prostate cancer: an update
Published in Expert Review of Molecular Diagnostics, 2019
Giuseppe Lucarelli, Davide Loizzo, Matteo Ferro, Monica Rutigliano, Mihai Dorin Vartolomei, Francesco Cantiello, Carlo Buonerba, Giuseppe Di Lorenzo, Daniela Terracciano, Ottavio De Cobelli, Carlo Bettocchi, Pasquale Ditonno, Michele Battaglia
Analysis of fatty acid and cholesterol homeostasis genes in the PCa patient cohort of the TCGA database (PRAD) through the cBioPortal [68], further supports the important role of these metabolic pathways in PCa development (Figures 2 and 3). For example, around 67% of the tumors from 491 PCa patients showed increased gene copy number or expression of fatty acid metabolism genes. Interestingly, analysis of MLYCD revealed deep deletions in approximately 25% of PCa patients. MLYCD encodes for malonyl-CoA decarboxylase, an enzyme that decarboxylates malonyl-CoA to acetyl-CoA, essentially reversing the reaction catalyzed by acetyl-CoA carboxylase.