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BioMed Research International
Volume 2014 (2014), Article ID 519310, 11 pages
Research Article

Early Changes in Costameric and Mitochondrial Protein Expression with Unloading Are Muscle Specific

1Balgrist University Hospital, University of Zurich, Switzerland
2Laboratory for Muscle Plasticity, Balgrist University Hospital, Forchstrasse 340, 8008 Zurich, Switzerland
3Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK
4National Aeronautics and Space Administration, Johnson Space Center, Houston, TX, USA
5Laboratoire de Physiologie de l’Exercice, EA4338, Faculté de Médecine, Université Jean-Monnet, Saint Etienne Cedex, France
6Department of Health Sciences, Mid Sweden University, Östersund, Sweden
7Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
8Department of Laboratory Medicine, Karolinska University Hospital, Clinical Physiology Karolinska Institute, Stockholm, Sweden

Received 9 June 2014; Accepted 23 August 2014; Published 16 September 2014

Academic Editor: Yvonne Mounier

Copyright © 2014 Martin Flück et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We hypothesised that load-sensitive expression of costameric proteins, which hold the sarcomere in place and position the mitochondria, contributes to the early adaptations of antigravity muscle to unloading and would depend on muscle fibre composition and chymotrypsin activity of the proteasome. Biopsies were obtained from vastus lateralis (VL) and soleus (SOL) muscles of eight men before and after 3 days of unilateral lower limb suspension (ULLS) and subjected to fibre typing and measures for costameric (FAK and FRNK), mitochondrial (NDUFA9, SDHA, UQCRC1, UCP3, and ATP5A1), and MHCI protein and RNA content. Mean cross-sectional area (MCSA) of types I and II muscle fibres in VL and type I fibres in SOL demonstrated a trend for a reduction after ULLS (). FAK phosphorylation at tyrosine 397 showed a 20% reduction in VL muscle (). SOL muscle demonstrated a specific reduction in UCP3 content (%; ). Muscle-specific effects of ULLS were identified for linear relationships between measured proteins, chymotrypsin activity and fibre MCSA. The molecular modifications in costamere turnover and energy homoeostasis identify that aspects of atrophy and fibre transformation are detectable at the protein level in weight-bearing muscles within 3 days of unloading.