Metabolic tracing reveals novel adaptations to skeletal muscle cell energy production pathways in response to NAD+ depletion

Background: Skeletal muscle is central to whole body metabolic homeostasis, with age and disease impairing its ability to function appropriately to maintain health. Inadequate NAD+ availability is proposed to contribute to pathophysiology by impairing metabolic energy pathway use. Despite the importance of NAD+ as a vital redox cofactor in energy production pathways being well-established, the wider impact of disrupted NAD+ homeostasis on these pathways is unknown. Methods: We utilised skeletal muscle myotube models to induce NAD+ depletion, repletion and excess and conducted metabolic tracing to provide comprehensive and detailed analysis of the consequences of altered NAD+ metabolism on central carbon metabolic pathways. We used stable isotope tracers, [1,2-13C] D-glucose and [U-13C] glutamine, and conducted combined 2D-1H,13C-heteronuclear single quantum coherence (HSQC) NMR spectroscopy and GC-MS analysis. Results: NAD+ excess driven by nicotinamide riboside (NR) supplementation within skeletal muscle cells resulted in enhanced nicotinamide clearance, but had no effect on energy homeostasis or central carbon metabolism. Nicotinamide phosphoribosyltransferase (NAMPT) inhibition induced NAD+ depletion and resulted in equilibration of metabolites upstream of glyceraldehyde phosphate dehydrogenase (GAPDH). Aspartate production through glycolysis and TCA cycle activity was increased in response to low NAD+, which was rapidly reversed with repletion of the NAD+ pool using NR. NAD+ depletion reversibly inhibits cytosolic GAPDH activity, but retains mitochondrial oxidative metabolism, suggesting differential effects of this treatment on sub-cellular pyridine pools. When supplemented, NR efficiently reversed these metabolic consequences. However, the functional relevance of increased aspartate levels after NAD+ depletion remains unclear, and requires further investigation. Conclusions: These data highlight the need to consider carbon metabolism and clearance pathways when investigating NAD+ precursor usage in models of skeletal muscle physiology.

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Metabolic tracing reveals novel adaptations to skeletal muscle cell energy production pathways in response to NAD+ depletion

Wellcome Open Research ◽

10.12688/wellcomeopenres.14898.1 ◽

2018 ◽

Vol 3 ◽

pp. 147 ◽

Cited By ~ 3

Author(s):

Lucy A. Oakey ◽

Rachel S. Fletcher ◽

Yasir S. Elhassan ◽

David M. Cartwright ◽

Craig L. Doig ◽

...

Keyword(s):

Skeletal Muscle ◽

Carbon Metabolism ◽

Energy Production ◽

Quantum Coherence ◽

Metabolic Energy ◽

Whole Body ◽

Muscle Physiology ◽

Nicotinamide Phosphoribosyltransferase ◽

Central Carbon ◽

Metabolic Tracing

Background: Skeletal muscle is central to whole body metabolic homeostasis, with age and disease impairing its ability to function appropriately to maintain health. Inadequate NAD+ availability is proposed to contribute to pathophysiology by impairing metabolic energy pathway use. Despite the importance of NAD+ as a vital redox cofactor in energy production pathways being well-established, the wider impact of disrupted NAD+ homeostasis on these pathways is unknown. Methods: We utilised skeletal muscle myotube models to induce NAD+ depletion, repletion and excess and conducted metabolic tracing to provide comprehensive and detailed analysis of the consequences of altered NAD+ metabolism on central carbon metabolic pathways. We used stable isotope tracers, [1,2-13C] D-glucose and [U-13C] glutamine, and conducted combined 2D-1H,13C-heteronuclear single quantum coherence (HSQC) NMR spectroscopy and GC-MS analysis. Results: NAD+ excess driven by nicotinamide riboside (NR) supplementation within skeletal muscle cells results in enhanced nicotinamide clearance, but had no effect on energy homeostasis or central carbon metabolism. Nicotinamide phosphoribosyltransferase (NAMPT) inhibition induced NAD+ depletion and resulted in equilibration of metabolites upstream of glyceraldehyde phosphate dehydrogenase (GAPDH). Aspartate production through glycolysis and TCA cycle activity is increased in response to low NAD+, which is rapidly reversed with repletion of the NAD+ pool using NR. NAD+ depletion reversibly inhibits cytosolic GAPDH activity, but retains mitochondrial oxidative metabolism, suggesting differential effects of this treatment on sub-cellular pyridine pools. When supplemented, NR efficiently reverses these metabolic consequences. However, the functional relevance of increased aspartate levels after NAD+ depletion remains unclear, and requires further investigation. Conclusions: These data highlight the need to consider carbon metabolism and clearance pathways when investigating NAD+ precursor usage in models of skeletal muscle physiology.

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NAD+ supplementation normalises central carbon metabolism in skeletal muscle: a mechanistic insight into the energetic consequences of age-related NAD+ decline

Endocrine Abstracts ◽

10.1530/endoabs.44.p187 ◽

2016 ◽

Author(s):

Lucy Oldacre-Bartley ◽

Rachel Fletcher ◽

Kate Hollinshead ◽

Yasir Elhassan ◽

Craig Doig ◽

...

Keyword(s):

Skeletal Muscle ◽

Carbon Metabolism ◽

Central Carbon Metabolism ◽

Mechanistic Insight ◽

Age Related ◽

Central Carbon ◽

Insight Into

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MODELING AND SIMULATION OF SKELETAL MUSCLE BASED ON METABOLISM PHYSIOLOGY

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519420400187 ◽

2020 ◽

Vol 20 (09) ◽

pp. 2040018

Author(s):

MONAN WANG ◽

JIALIN HAN ◽

QIYOU YANG

Keyword(s):

Skeletal Muscle ◽

Energy Metabolism ◽

Calcium Ion ◽

Energy Systems ◽

Metabolic Energy ◽

Ion Concentration ◽

Whole Body ◽

Muscle Energy Metabolism ◽

Calcium Ion Transport

Skeletal muscle energy metabolism plays a very important role in controlling movement of the whole body and has important theoretical guidance for making exercise training plans and losing weight. In this paper, we developed a mathematical model of skeletal muscle excitation–contraction pathway based on the energy metabolism that links excitation to contraction to explore the effects of different metabolic energy systems on calcium ion changes and the force during skeletal muscle contraction. In this paper, a membrane potential model, a calcium cycle model, a cross-bridge dynamics model and an energy metabolism model were established. Finally, the physiological phenomenon of calcium ion transport and calcium ion concentration change of the sarcoplasm was simulated. The results show that the phosphagen system has the fastest metabolic rate and the phosphagen system has the largest impact on the explosive power of skeletal muscle exercise. The specific characteristics of the three metabolic energy systems supporting skeletal muscle movement in vivo were also analyzed in detail.

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Energy coupling to sodium transport in frog skeletal muscle

AJP Cell Physiology ◽

10.1152/ajpcell.1978.235.1.c25 ◽

1978 ◽

Vol 235 (1) ◽

pp. C25-C34 ◽

Cited By ~ 5

Author(s):

R. J. Connett ◽

E. T. Hays

Keyword(s):

Skeletal Muscle ◽

Energy Production ◽

Atp Hydrolysis ◽

Energy Coupling ◽

Creatine Phosphate ◽

Coupling Factor ◽

Metabolic Energy ◽

Frog Skeletal Muscle ◽

Energy Turnover ◽

Sodium Efflux

In addition to a strophanthidin-sensitive (SS) sodium efflux, a large component of the sodium efflux in freshly isolated frog skeletal muscle is sodium-activated and strophanthidin-insensitive (SASI). The amount of metabolic energy associated with sodium movement by each of these components was measured and the coupling between sodium movement and adenosine 5'-triphosphate (ATP) hydrolysis in muscle was calculated. Energy production was blocked by iodoacetate and cyanide. Energy turnover was estimated from the change in creatine phosphate (CrP) and ATP contents and expressed as potential energy (PE = CrP + 2ATP). After metabolic poisoning a linear fall of PE occurred (6.3 mumol/g.h). Metabolic poisoning had no effect on the magnitude of the SS or SASI components of sodium efflux. In 2 h the sodium moved, and PE change due to the SS component was 4.35 and 1.66 mumol/g.h, respectively, which gave a coupling factor of 2.6. The amount of sodium moved by the SASI component was similar to that moved by the SS component in 2 h whereas no energy change was observed. It was, therefore, concluded that sodium movement by the SASI component requires no energy input.

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The Essential Role of Cholesterol Metabolism in the Intracellular Survival of Mycobacterium leprae Is Not Coupled to Central Carbon Metabolism and Energy Production

Journal of Bacteriology ◽

10.1128/jb.00625-15 ◽

2015 ◽

Vol 197 (23) ◽

pp. 3698-3707 ◽

Cited By ~ 14

Author(s):

Maria Angela M. Marques ◽

Marcia Berrêdo-Pinho ◽

Thabatta L. S. A. Rosa ◽

Venugopal Pujari ◽

Robertha M. R. Lemes ◽

...

Keyword(s):

Carbon Metabolism ◽

Energy Production ◽

Essential Role ◽

Cholesterol Metabolism ◽

Mycobacterium Leprae ◽

Intracellular Survival ◽

Central Carbon Metabolism ◽

Content Type ◽

Central Carbon

ABSTRACTMycobacterium lepraeinduces the formation of lipid droplets, which are recruited to pathogen-containing phagosomes in infected macrophages and Schwann cells. Cholesterol is among the lipids with increased abundance inM. leprae-infected cells, and intracellular survival relies on cholesterol accumulation. The present study investigated the capacity ofM. lepraeto acquire and metabolize cholesterol.In silicoanalyses showed that oxidation of cholesterol to cholest-4-en-3-one (cholestenone), the first step of cholesterol degradation catalyzed by the enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD), is apparently the only portion of the cholesterol catabolic pathway seen inMycobacterium tuberculosispreserved byM. leprae. Incubation of bacteria with radiolabeled cholesterol confirmed thein silicopredictions. Radiorespirometry and lipid analyses performed after incubatingM. lepraewith [4-14C]cholesterol or [26-14C]cholesterol showed the inability of this pathogen to metabolize the sterol rings or the side chain of cholesterol as a source of energy and carbon. However, the bacteria avidly incorporated cholesterol and, as expected, converted it to cholestenone bothin vitroandin vivo. Our data indicate thatM. lepraehas lost the capacity to degrade and utilize cholesterol as a nutritional source but retains the enzyme responsible for its oxidation to cholestenone. Thus, the essential role of cholesterol metabolism in the intracellular survival ofM. lepraeis uncoupled from central carbon metabolism and energy production. Further elucidation of cholesterol metabolism in the host cell duringM. lepraeinfection will establish the mechanism by which this lipid supportsM. lepraeintracellular survival and will open new avenues for novel leprosy therapies.IMPORTANCEOur study focused on the obligate intracellular pathogenMycobacterium lepraeand its capacity to metabolize cholesterol. The data make an important contribution for those interested in understanding the mechanisms of mycobacterial pathogenesis, since they indicate that the essential role of cholesterol forM. lepraeintracellular survival does not rely on its utilization as a nutritional source. Our findings reinforce the complexity of cholesterol's role in sustainingM. lepraeinfection. Further elucidation of cholesterol metabolism in the host cell duringM. lepraeinfection will establish the mechanism by which this lipid supportsM. lepraeintracellular survival and will open new avenues for novel leprosy therapies.

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Faculty Opinions recommendation of Dynamic proteomic analysis reveals a switch between central carbon metabolism and alcoholic fermentation in rice filling grains.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1119387.575575 ◽

2008 ◽

Author(s):

Richard Leegood

Keyword(s):

Carbon Metabolism ◽

Proteomic Analysis ◽

Alcoholic Fermentation ◽

Central Carbon Metabolism ◽

Central Carbon

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Neural control of glucose uptake by skeletal muscle after central administration of NMDA

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.268.2.r492 ◽

1995 ◽

Vol 268 (2) ◽

pp. R492-R497 ◽

Cited By ~ 1

Author(s):

C. H. Lang ◽

M. Ajmal ◽

A. G. Baillie

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Glucose Uptake ◽

Neural Control ◽

Plasma Insulin ◽

Regional Blood Flow ◽

Muscle Blood Flow ◽

Whole Body ◽

Glucose Disposal ◽

Central Administration

Intracerebroventricular injection of N-methyl-D-aspartate (NMDA) produces hyperglycemia and increases whole body glucose uptake. The purpose of the present study was to determine in rats which tissues are responsible for the elevated rate of glucose disposal. NMDA was injected intracerebroventricularly, and the glucose metabolic rate (Rg) was determined for individual tissues 20-60 min later using 2-deoxy-D-[U-14C]glucose. NMDA decreased Rg in skin, ileum, lung, and liver (30-35%) compared with time-matched control animals. In contrast, Rg in skeletal muscle and heart was increased 150-160%. This increased Rg was not due to an elevation in plasma insulin concentrations. In subsequent studies, the sciatic nerve in one leg was cut 4 h before injection of NMDA. NMDA increased Rg in the gastrocnemius (149%) and soleus (220%) in the innervated leg. However, Rg was not increased after NMDA in contralateral muscles from the denervated limb. Data from a third series of experiments indicated that the NMDA-induced increase in Rg by innervated muscle and its abolition in the denervated muscle were not due to changes in muscle blood flow. The results of the present study indicate that 1) central administration of NMDA increases whole body glucose uptake by preferentially stimulating glucose uptake by skeletal muscle, and 2) the enhanced glucose uptake by muscle is neurally mediated and independent of changes in either the plasma insulin concentration or regional blood flow.

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