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Title

UCP3 protein regulation in human skeletal muscle fibre types I, IIa and IIx is dependent on exercise intensity

Authors
Praz, Manu
Crettenand, Antoinette
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Published in Journal of Physiology. 2003, vol. 550, no. Pt 3, p. 855-61
Abstract It has been proposed that mitochondrial uncoupling protein 3 (UCP3) behaves as an uncoupler of oxidative phosphorylation. In a cross-sectional study, UCP3 protein levels were found to be lower in all fibre types of endurance-trained cyclists as compared to healthy controls. This decrease was greatest in the type I oxidative fibres, and it was hypothesised that this may be due to the preferential recruitment of these fibres during endurance training. To test this hypothesis, we compared the effects of 6 weeks of endurance (ETr) and sprint (STr) running training on UCP3 mRNA expression and fibre-type protein content using real-time PCR and immunofluorescence techniques, respectively. UCP3 mRNA and protein levels were downregulated similarly in ETr and STr (UCP3 mRNA: by 65 and 50%, respectively; protein: by 30 and 27%, respectively). ETr significantly reduced UCP3 protein content in type I, IIa and IIx muscle fibres by 54, 29 and 16%, respectively. STr significantly reduced UCP3 protein content in type I, IIa and IIx muscle fibres by 24, 31 and 26%, respectively. The fibre-type reductions in UCP3 due to ETr, but not STr, were significantly different from each other, with the effect being greater in type I than in type IIa, and in type IIa than in type IIx fibres. As a result, compared to STr, ETr reduced UCP3 expression significantly more in fibre type I and significantly less in fibre types IIx. This suggests that the more a fibre is recruited, the more it adapts to training by a decrease in its UCP3 expression. In addition, the more a fibre type depends on fatty acid beta oxidation and oxidative phosphorylation, the more it responds to ETr by a decrease in its UCP3 content.
Keywords AdultAnaerobic Threshold/physiologyBody Composition/physiologyCarrier Proteins/biosynthesis/genetics/metabolismExercise/physiologyFluorescent Antibody TechniqueHumansIon ChannelsIsoenzymes/biosynthesis/geneticsMaleMitochondrial ProteinsMuscle FibersFast-Twitch/metabolism/physiologyMuscle FibersSlow-Twitch/metabolism/physiologyMuscleSkeletal/cytology/metabolismMyosin Heavy Chains/metabolismOxygen Consumption/physiologyPhysical Endurance/physiologyPhysical Fitness/physiologyRNAMessenger/biosynthesisReverse Transcriptase Polymerase Chain Reaction
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PMID: 12794174
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Research group HIV (835)
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RUSSELL, Aaron Paul et al. UCP3 protein regulation in human skeletal muscle fibre types I, IIa and IIx is dependent on exercise intensity. In: Journal of Physiology, 2003, vol. 550, n° Pt 3, p. 855-61. https://archive-ouverte.unige.ch/unige:26071

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Deposited on : 2013-01-31

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