Proteomic analysis of mouse soleus muscles affected by hindlimb unloading and reloading

Introduction: Disuse muscle atrophy, induced by prolonged space flight, bed rest, or denervation, is a common process with obvious changes in slow-twitch soleus muscles. Methods: Proteomic analysis was performed on mouse soleus subjected to hindlimb unloading (HU) and hindlimb reloading (HR) to identify new dysregulated proteins. Results: Following HU, the mass and cross-sectional area of muscle fibers decreased, but they recovered after HR. Proteomic analyses revealed 9 down-regulated and 7 up-regulated proteins in HU, and 2 down-regulated and 5 up-regulated proteins in HR. The dysregulated proteins were mainly involved in energy metabolism, protein degradation, and cytoskeleton stability. Among the dysregulated proteins were fatty acid binding protein 3, α-B crystalline, and transthyretin. Conclusions: These results indicate that muscle atrophy induced by unloading is related to activation of proteolysis, metabolic alterations toward glycolysis, destruction of myofibrillar integrity, and dysregulation of heat shock proteins (HSPs). The dysregulated proteins may play a role in muscle atrophy and the recovery process. Muscle Nerve 52: 803–811, 2015