Role of Protein Turnover in Adaptation.

[Mike Bikov]

J Physiol. 2012 Jan 30. [Epub ahead of print]

Role of Protein Turnover in Adaptation.

Atherton PJ, Smith K.

University of Nottingham.

Exercise-induced alterations in protein turnover underlie chronic physiological adaptations to training. It therefore follows that capturing the acute effects of exercise on muscle protein synthesis (MPS) and breakdown (MPB) in humans using stable isotope methodologies represents a reference point for adaptive potential and a cornerstone of research in this arena. In healthy, recreationally active individuals both muscle mass and phenotype remain stable, with mixed muscle proteins displaying lowish diurnal turnover rates (~1.2%.d. 1¬¬) and existing in dynamic equilibrium i.e. MPB>MPS [fasted] and MPS>MPB [fed]. However, an exercise bout triggers mechanotransduction and physico-chemical (i.e. endocrine, auto/para-crine) sensory mechanisms. Subsequent activation of intramuscular signalling modulates the cellular apparatus regulating both post-translational control of protein turnover and gene expression (mRNA/ miRNA). Collectively, it is these changes that underlie the chronic alteration in composition and/or quantity of skeletal muscle proteins that are the hallmark of physiological adaptive responses to exercise training. Moreover, intricate selectivity over both the amount and species of proteins to be synthesised or degraded underlies the exquisite adaptive specificity to distinct training regimens (e.g. hypertrophy, mitochondrial biogenesis). The objective of this review is to highlight our current understanding of protein turnover responses to exercise and also the sensing and signaling mechanisms involved.​

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