Proteome dysregulation of mitochondria in gastrocnemius, triceps and soleus muscles in aged rats

Muscle mitochondrial metabolism plays a pivotal role under physiological (ageing), paraphysiological (hypoxia) and pathological conditions (Hearth disease and cancer). The identification of protein changed during ageing represents a crucial step for a specific therapeutic targeting and for understanding the modulation of mitochondrial function. Our study is aimed at the assessment of changes in mitochondrial proteome induced by aging in different muscles characterized by a different fiber type composition and function such as gastrocnemius, triceps and soleus. Protein dysregulation was identified in the subsarcolemmal mitochondrial fractions by 2D-DIGE and MALDI TOF and ESI MS/MS. In addition, to relate fiber type distribution and mitochondrial protein dysregulation, myosin heavy chain isoforms composition and citrate synthase assay were assessed. Results of MyHC isoforms distribution and citrate synthase activity highlighted a behaviour at variance in different muscles in course of aging, suggesting a major involvement of gastrocnemius and soleus in this physiological process. The 2D-DIGE approach indicated a general down-regulation in proteins involved in respiratory chain, Krebs cycle, transport, stress control and protein synthesis. These results suggested that the ageing process causes several alterations in a large number of proteins that regulate the power plant of muscular cells and can be associated to the decline of muscular function during ageing.