Denervation-induced muscle atrophy is an extremely complex process that involves numerous molecules and signaling pathways.To understand the molecular mechanism of denervation-induced skeletal muscle atrophy,isobaric tags for relative and absolute quantitation (iTRAQ) were used to highlight differentially expressed proteins in the rat tibialis anterior muscle after sciatic nerve transection.A total of 110 differentially expressed proteins were detected.Gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted for protein functional annotation and pathway identification.The results of protein functional annotation indicated that metabolic enzymes represented the largest class of differentially expressed proteins,followed by structural proteins and signaling molecules.The KEGG analysis also indicated that proteins involved in glycolysis displayed the most marked difference,followed by those involved with the citrate cycle.Among the differentially expressed proteins involved in glycolysis,a-enolase and p-enolase were chosen for validation by western blot and immunohistochemistry.The up-regulation of a-enolase may play a complex role in the regulation of denervation-induced muscle atrophy,while the downregulation of p-enolase may be associated with the reduced production of adenosine triphosphate,the failure to maintain the fast-twitch skeletal muscle phenotype,and the degeneration of myoflbers after denervation.Protein-protein interactions analysis indicated that TRAF6,which was not observed by iTRAQ directly,should be up-regulated in the denervated muscle,and this was validated by western blotting.The up-regulated TRAF6 might participate in the development of denervation-induced muscle atrophy in part by regulating the expression of MAFBx and MuRF1.These data provide valuable clues to better understand the molecular mechanisms regulating denervation-induced muscle atrophy.