Mitochondrial dysfunction has been thought to play roles in the pathogenesis of diabetic nephropathy (Dn). However, precise mechanisms underlying mitochondrial dysfunction in Dn remained unclear. Herein, mitochondria were isolated from renal tubular cells after exposure to normal glucose (5.5 mM glucose), high glucose (25 mM glucose), or osmotic control (5.5 mM glucose + 19.5 mM mannitol) for 96 h. Comparative proteomic analysis revealed six differentially expressed proteins among groups that were subsequently identified by tandem mass spectrometry (nanoLC-ESI-ETD MS/MS) and confirmed by Western blotting. Several various types of post-translational modifications (PTMs) were identified in all of these identified proteins. Interestingly, phosphorylation and oxidation were most abundant in mitochondrial proteins whose levels were exclusively increased in high glucose condition. The high glucose-induced increases in phosphorylation and oxidation of mitochondrial proteins were successfully confirmed by various assays including MS/MS analyses. Moreover, high glucose also increased levels of phosphorylated ezrin, intracellular Atp and RoS, all of which could be abolished by a p38 MAPK inhibitor (SB239063), implicating a role of p38 MAPK-mediated phosphorylation in high glucose-induced mitochondrial dysfunction. These data indicate that phosphorylation and oxidation of mitochondrial proteins are, at least in part, involved in mitochondrial dysfunction in renal tubular cells during Dn. Mitochondria play important roles in many cellular processes, e.g., ATP production, calcium homeostasis, regulation of cellular metabolism, and apoptotic cell death 1. Mitochondrial dysfunction frequently causes cellular injury and is involved in the pathogenesis of several diseases 2. In diabetes, overproduction of reactive oxygen species (ROS) is a result of mitochondrial dysfunction and has been proposed as one of the key initiators contributing to development of diabetic nephropathy (DN) 3. Moreover, high glucose-induced mitochondrial dysfunction results to a decline of ATP production and activation of apoptotic pathway, which ultimately leads to renal cell injury and death 4,5. Several studies have suggested that DN is associated with alterations in mitochondrial dynamics, morphology, and autophagic removal of damaged mitochondria (mitophagy), which play important roles in regulation of mitochondrial function and homeostasis 6. The enlargement of mitochondria in proximal renal tubular cells has been reported to correlate with microalbuminuria in diabetic rats 7. Recent studies have demonstrated that hyperglycemia induces mitochondrial fission and fragmentation in renal cells that are associated with ROS overproduction, increased mitophagy and apoptosis 8,9. These lines of evidence indicate that high glucose causes mitochondrial dysfunction leading to renal cell injury. Nevertheless, precise mechanisms underlying mitochondrial dysfunction induced by diabetes are not well understood and remain to be elucidated. Our present study, therefo...

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