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Costamere remodeling with muscle loading and unloading in healthy young men

Li, R and Narici, MV and Erskine, RM and Seynnes, OR and Rittweger, J and Pisot, R and Simunic, B and Flueck, M (2013) Costamere remodeling with muscle loading and unloading in healthy young men. JOURNAL OF ANATOMY, 223 (5). pp. 525-536. ISSN 0021-8782

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Abstract

Costameres are mechano-sensory sites of focal adhesion in the sarcolemma that provide a structural anchor for myofibrils. Their turnover is regulated by integrin-associated focal adhesion kinase (FAK). We hypothesized that changes in content of costamere components (beta 1 integrin, FAK, meta-vinculin, gamma-vinculin) with increased and reduced loading of human anti-gravity muscle would: (i) relate to changes in muscle size and molecular parameters of muscle size regulation [p70S6K, myosin heavy chain (MHC)1 and MHCIIA]; (ii) correspond to adjustments in activity and expression of FAK, and its negative regulator, FRNK; and (iii) reflect the temporal response to reduced and increased loading. Unloading induced a progressive decline in thickness of human vastus lateralis muscle after 8 and 34 days of bedrest (−4% and −14%, respectively; n = 9), contrasting the increase in muscle thickness after 10 and 27 days of resistance training (+5% and +13%; n = 6). Changes in muscle thickness were correlated with changes in cross-sectional area of type I muscle fibers (r = 0.66) and beta 1 integrin content (r = 0.76) at the mid-point of altered loading. Changes in meta-vinculin and FAK-pY397 content were correlated (r = 0.85) and differed, together with the changes of beta 1 integrin, MHCI, MHCII and p70S6K, between the mid- and end-point of resistance training. By contrast, costamere protein level changes did not differ between time points of bedrest. The findings emphasize the role of FAK-regulated costamere turnover in the load-dependent addition and removal of myofibrils, and argue for two phases of muscle remodeling with resistance training, which do not manifest at the macroscopic level.

Item Type: Article
Uncontrolled Keywords: 0903 Biomedical Engineering, 1116 Medical Physiology
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Publisher: WILEY-BLACKWELL
Related URLs:
Date Deposited: 04 Apr 2016 08:35
Last Modified: 04 Apr 2016 08:35
DOI or Identification number: 10.1111/joa.12101
URI: http://researchonline.ljmu.ac.uk/id/eprint/3365

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