Defining the transcriptomic and proteomic profiles of rat ageing skeletal muscle by the use of a cDNA array, 2D- and Blue native-PAGE approach.

We defined the transcriptomic and proteomic profiles of rat ageing skeletal muscle using a combined cDNA array, 2D- and Blue native-PAGE approach. This was allowed to obtain an overview of the interrelated events leading to the transcriptome/proteome/mitoproteome changes likely to underlie the structural/metabolic features of aged skeletal muscle. The main differences were found in genes/proteins related to energy metabolism, mitochondrial pathways, myofibrillar filaments, and detoxification. Concerning the abundance of mitochondrial OXPHOS complexes as well as their supramolecular organization and activity, mitochondria from old rats, when compared with those from young rats, contained significantly lower amounts of complex I (NADH:ubiquinone oxidoreductase), V (FoF1-ATP synthase), and III (ubiquinol:cytochrome c oxidoreductase). The same mitochondria contained a significantly larger amount of complex II (succinate:ubiquinone oxidoreductase), but an unchanged amount of complex IV (cytochrome c oxidase, COX). When comparing the supercomplex profiles between young and old muscle mitochondria, the densitometric analysis revealed that lighter supercomplexes were significantly reduced in older mitochondria, and that in the older group the major supercomplex bands were those representing heavier supercomplexes, likely suggesting a compensatory mechanism that, in ageing muscle, is functionally directed towards substrate channeling and catalytic enhancement advantaging the respirosome.