Sensitivity of CPT I to malonyl-CoA in trained and untrained human skeletal muscle

2000 ◽  
Vol 278 (3) ◽  
pp. E462-E468 ◽  
Author(s):  
Emma C. Starritt ◽  
Richard A. Howlett ◽  
George J. F. Heigenhauser ◽  
Lawrence L. Spriet
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Aerobic Training ◽  
Fat Metabolism ◽  
Acetyl Coa ◽  
Malonyl Coa ◽  
Metabolic Conditions ◽  
Carnitine Palmitoyltransferase I ◽  
Cpt I ◽  
Rest And Exercise

The present study examined the sensitivity of carnitine palmitoyltransferase I (CPT I) activity to its inhibitor malonyl-CoA (M-CoA), and simulated metabolic conditions of rest and exercise, in aerobically trained and untrained humans. Maximal CPT I activity was measured in mitochondria isolated from resting human skeletal muscle. Mean CPT I activity was 492.8 ± 72.8 and 260.8 ± 33.6 μmol ⋅ min−1 ⋅ kg wet muscle−1 in trained and untrained subjects, respectively (pH 7.0, 37°C). The sensitivity to M-CoA was greater in trained muscle; the IC50 for M-CoA was 0.17 ± 0.04 and 0.49 ± 0.17 μM in trained and untrained muscle, respectively. The presence of acetyl-CoA, free coenzyme A (CoASH), and acetylcarnitine, in concentrations simulating rest and exercise conditions did not release the M-CoA-induced inhibition of CPT I activity. However, CPT I activity was reduced at pH 6.8 vs. pH 7.0 in both trained and untrained muscle in the presence of physiological concentrations of M-CoA. The results of this study indicate that aerobic training is associated with an increase in the sensitivity of CPT I to M-CoA. Accumulations of acetyl-CoA, CoASH, and acetylcarnitine do not counteract the M-CoA-induced inhibition of CPT I activity. However, small decreases in pH produce large reductions in the activity of CPT I and may contribute to the decrease in fat metabolism that occurs during moderate and intense aerobic exercise intensities.

CPT I ACTIVITY AND MALONYL-COA SENSITIVITY IN AEROBICALLY TRAINED AND UNTRAINED HUMAN SKELETAL MUSCLE.

1998 ◽  
Vol 30 (Supplement) ◽  
pp. 137 ◽  
Author(s):  
E C Starritt ◽  
R A Howlett ◽  
G JF Heigenhauser ◽  
M Hargreaves ◽  
L L Spriet
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Malonyl Coa ◽  
Cpt I ◽  
Aerobically Trained

Malonyl-CoA and carnitine in regulation of fat oxidation in human skeletal muscle during exercise

2005 ◽  
Vol 288 (1) ◽  
pp. E133-E142 ◽  
Author(s):  
Carsten Roepstorff ◽  
Nils Halberg ◽  
Thore Hillig ◽  
Asish K. Saha ◽  
Neil B. Ruderman ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Human Skeletal Muscle ◽  
Fat Oxidation ◽  
Free Carnitine ◽  
Carbohydrate Diet ◽  
Acetyl Coa ◽  
Low Carbohydrate Diet ◽  
Malonyl Coa ◽  
Amp Activated Protein Kinase

Intracellular mechanisms regulating fat oxidation were investigated in human skeletal muscle during exercise. Eight young, healthy, moderately trained men performed bicycle exercise (60 min, 65% peak O2 consumption) on two occasions, where they ingested either 1) a high-carbohydrate diet (H-CHO) or 2) a low-carbohydrate diet (L-CHO) before exercise to alter muscle glycogen content as well as to induce, respectively, low and high rates of fat oxidation. Leg fat oxidation was 122% higher during exercise in L-CHO than in H-CHO ( P < 0.001). In keeping with this, the activity of α2-AMP-activated protein kinase (α2-AMPK) was increased twice as much in L-CHO as in H-CHO ( P < 0.01) at 60 min of exercise. However, acetyl-CoA carboxylase (ACC)β Ser221 phosphorylation was increased to the same extent (6-fold) under the two conditions. The concentration of malonyl-CoA was reduced 13% by exercise in both conditions ( P < 0.05). Pyruvate dehydrogenase activity was higher during exercise in H-CHO than in L-CHO ( P < 0.01). In H-CHO only, the concentrations of acetyl-CoA and acetylcarnitine were increased ( P < 0.001), and the concentration of free carnitine was decreased ( P < 0.01), by exercise. The data suggest that a decrease in the concentration of malonyl-CoA, secondary to α2-AMPK activation and ACC inhibition (by phosphorylation), contributes to the increase in fat oxidation observed at the onset of exercise regardless of muscle glycogen levels. They also suggest that, with high muscle glycogen, the availability of free carnitine may limit fat oxidation during exercise, due to its increased use for acetylcarnitine formation.

scholarly journals Human skeletal muscle carnitine palmitoyltransferase I activity determined in isolated intact mitochondria

1998 ◽  
Vol 85 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Phanélie M. Berthon ◽  
Richard A. Howlett ◽  
George J. F. Heigenhauser ◽  
Lawrence L. Spriet
Keyword(s):  
Skeletal Muscle ◽  
Citrate Synthase ◽  
Vastus Lateralis ◽  
Maximal Oxygen Consumption ◽  
Carnitine Palmitoyltransferase ◽  
Vastus Lateralis Muscle ◽  
Malonyl Coa ◽  
Human Muscle Biopsy ◽  
Carnitine Palmitoyltransferase I ◽  
Cpt I

This study was designed to compare the activity of skeletal muscle carnitine palmitoyltransferase I (CPT I) in trained and inactive men ( n = 14) and women ( n = 12). CPT I activity was measured in intact mitochondria, isolated from needle biopsy vastus lateralis muscle samples (∼60 mg). The variability of CPT I activity determined on two biopsy samples from the same leg on the same day was 4.4, whereas it was 7.0% on two biopsy samples from the same leg on different days. The method was sensitive to the CPT I inhibitor malonyl-CoA (88% inhibition) and therefore specific for CPT I activity. The mean CPT I activity for all 26 subjects was 141.1 ± 10.6 μmol ⋅ min−1 ⋅ kg wet muscle (wm)−1 and was not different when all men vs. all women (140.5 ± 15.7 and 142.2 ± 14.5 μmol ⋅ min−1 ⋅ kg wm−1, respectively) were compared. However, CPT I activity was significantly higher in trained vs. inactive subjects for both men (176.2 ± 21.1 vs. 104.1 ± 13.6 μmol ⋅ min−1 ⋅ kg wm−1) and women (167.6 ± 14.1 vs. 91.2 ± 9.5 μmol ⋅ min−1 ⋅ kg wm−1). CPT I activity was also significantly correlated with citrate synthase activity (all subjects, r = 0.76) and maximal oxygen consumption expressed in milliliters per kilogram per minute (all subjects, r = 0.69). The results of this study suggest that CPT I activity can be accurately and reliably measured in intact mitochondria isolated from human muscle biopsy samples. CPT I activity was not affected by gender, and higher activities in aerobically trained subjects appeared to be the result of increased mitochondrial content in both men and women.

scholarly journals Interaction of malonyl-CoA and related compounds with mitochondria from different rat tissues. Relationship between ligand binding and inhibition of carnitine palmitoyltransferase I

1983 ◽  
Vol 214 (1) ◽  
pp. 83-91 ◽  
Author(s):  
S E Mills ◽  
D W Foster ◽  
J D McGarry
Keyword(s):  
Skeletal Muscle ◽  
Site Occupancy ◽  
Carnitine Palmitoyltransferase ◽  
Rat Tissues ◽  
Skeletal Muscle Mitochondria ◽  
Malonyl Coa ◽  
High Affinity Binding Site ◽  
Carnitine Palmitoyltransferase I ◽  
Cpt I ◽  
Related Compounds

The sensitivity of carnitine palmitoyltransferase I (CPT I; EC 2.3.1.21) to inhibition by malonyl-CoA and related compounds was examined in isolated mitochondria from liver, heart and skeletal muscle of the rat. In all three tissues the same order of inhibitory potency emerged: malonyl-CoA much greater than succinyl-CoA greater than methylmalonyl-CoA much greater than propionyl-CoA greater than acetyl-CoA. For any given agent, suppression of CPT I activity was much greater in skeletal muscle than in liver, with the heart enzyme having intermediate sensitivity. With skeletal-muscle mitochondria a high-affinity binding site for [14C]malonyl-CoA was readily demonstrable (Kd approx. 25 nM). The ability of other CoA esters to compete with [14C]malonyl-CoA for binding to the membrane paralleled their capacity to inhibit CPT I. Palmitoyl-CoA also competitively inhibited [14C]malonyl-CoA binding, in keeping with its known ability to overcome malonyl-CoA suppression of CPT I. For reasons not yet clear, free CoA displayed anomalous behaviour in that its competition for [14C]malonyl-CoA binding was disproportionately greater than its inhibition of CPT I. Three major conclusions are drawn. First, malonyl-CoA is not the only physiological compound capable of suppressing CPT I, since chemically related compounds, known to exist in cells, also share this property, particularly in tissues where the enzyme shows the greatest sensitivity to malonyl-CoA. Second, malonyl-CoA and its analogues appear to interact with the same site on the mitochondrial membrane, as may palmitoyl-CoA. Third, the degree of site occupancy by inhibitors governs the activity of CPT I.

scholarly journals Effects of pH on the interaction of substrates and malonyl-CoA with mitochondrial carnitine palmitoyltransferase I

1984 ◽  
Vol 219 (2) ◽  
pp. 601-608 ◽  
Author(s):  
S E Mills ◽  
D W Foster ◽  
J D McGarry
Keyword(s):  
Skeletal Muscle ◽  
Binding Site ◽  
Liver Mitochondria ◽  
Fatty Acyl ◽  
Carnitine Palmitoyltransferase ◽  
Skeletal Muscle Mitochondria ◽  
Malonyl Coa ◽  
Effects Of Ph ◽  
Carnitine Palmitoyltransferase I ◽  
Cpt I

The kinetics of carnitine palmitoyltransferase I (CPT I; EC 2.3.1.21) were examined in mitochondria from rat liver, heart and skeletal muscle as a function of pH over the range 6.8-7.6. In all three tissues raising the pH resulted in a fall in the Km for carnitine, no change in the Km for palmitoyl-CoA or Octanoyl-CoA, and a marked decrease in the inhibitory potency of malonyl-CoA. Studies with skeletal-muscle mitochondria established that increasing pH was accompanied by an increase in the Kd of the malonyl-CoA binding site for this ligand, coupled with a decrease in the Kd for fatty acyl-CoA species to compete for malonyl-CoA binding. Three principal conclusions are drawn. (1) The pH-induced shift in malonyl-CoA sensitivity of CPT I is not a phenomenon restricted to liver mitochondria. (2) At any given pH within the range tested, the ability of malonyl-CoA (and closely related compounds) to inhibit enzyme activity is governed by the efficiency of their binding to the malonyl-CoA site. (3) The competitive interaction between fatty acyl-CoA substrates and malonyl-CoA as regards CPT I activity is exerted at the malonyl-CoA binding site. Finally, the possibility is strengthened that the malonyl-CoA binding site is distinct from the active site of CPT I.

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

2005 ◽  
Vol 98 (4) ◽  
pp. 1221-1227 ◽  
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.

scholarly journals Effect of aerobic training on baseline expression of signaling and respiratory proteins in human skeletal muscle

2018 ◽  
Vol 6 (17) ◽  
pp. e13868 ◽  
Author(s):  
Daniil V. Popov ◽  
Evgeny A. Lysenko ◽  
Roman O. Bokov ◽  
Maria A. Volodina ◽  
Nadia S. Kurochkina ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Aerobic Training ◽  
Respiratory Proteins
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