Altered O‐GlcNAc Modification and Phosphorylation of Mitochondrial Proteins in Myoblast Cells Exposed to High Glucose

Hyperglycemia induced increased posttranslational modification of proteins by O ‐linked‐β‐ N ‐acetyl glucosamine ( O ‐GlcNAcylation) and mitochondrial dysfunction has been independently implicated in the development of insulin resistance. It is not known whether repertoire of O ‐GlcNAcylated proteins includes mitochondrial proteins and their altered O ‐GlcNAcylation impinges on their phosphorylation mediated normal functioning thus contribute to mitochondrial dysfunction and insulin resistance. We have explored the O ‐GlcNAcylation of mitochondrial proteins from myoblast cells under basal (4 mM) and high glucose (30 mM) conditions using a combination of proteomic approaches. Furthermore, we have assessed the accompanied changes in the phosphorylation of mitochondrial proteins. We report that a number of mitochondrial proteins are O ‐GlcNAcylated under basal condition, which is altered under high glucose condition. In addition, we report that exposure to high glucose not only changes the O ‐GlcNAcylation of mitochondrial proteins but also changes their phosphorylation profiles, thus can contribute to mitochondrial dysfunction and insulin resistance. This work was made possible by financial support from Manitoba Health Research Council (MHRC) and Winnipeg Health Sciences Centre Foundation. SM is a recipient of MMSF Career Development Award and SRA is supported by MHRC postdoctoral fellowship.