title: Increased enzymatic O-GlcNAcylation of mitochondrial proteins impairs mitochondrial function in cardiac myocytes exposed to high glucose.
abstract: Increased nuclear protein O-linked beta-N-acetylglucosamine glycosylation (O-GlcNAcylation) mediated by high glucose treatment or the hyperglycemia of diabetes mellitus contributes to cardiac myocyte dysfunction. However, whether mitochondrial proteins in cardiac myocytes are also submitted to O-GlcNAcylation or excessive O-GlcNAcylation alters mitochondrial function is unknown. In this study, we determined if mitochondrial proteins are O-GlcNAcylated and explored if increased O-GlcNAcylation is linked to high glucose-induced mitochondrial dysfunction in neonatal rat cardiomyocytes. By immunoprecipitation, we found that several mitochondrial proteins, which are members of complexes of the respiratory chain, like subunit NDUFA9 of complex I, subunits core 1 and core 2 of complex III, and the mitochondrial DNA-encoded subunit I of complex IV (COX I) are O-GlcNAcylated. By mass spectrometry, we identified that serine 156 on NDUFA9 is O-GlcNAcylated. High glucose treatment (30 mm glucose) increases mitochondrial protein O-GlcNAcylation, including those of COX I and NDUFA9 which are reduced by expression of O-GlcNAcase (GCA). Increased mitochondrial O-GlcNAcylation is associated with impaired activity of complex I, III, and IV in addition to lower mitochondrial calcium and cellular ATP content. When the excessive O-GlcNAc modification is reduced by GCA expression, mitochondrial function improves; the activity of complex I, III, and IV increases to normal and mitochondrial calcium and cellular ATP content are returned to control levels. From these results we conclude that specific mitochondrial proteins of cardiac myocytes are O-GlcNAcylated and that exposure to high glucose increases mitochondrial protein O-GlcNAcylation, which in turn contributes to impaired mitochondrial function.
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Yong
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Jorge
authors.initials: J
authors.lastname: Suarez
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Fricovsky
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Scott
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Sunia A
authors.initials: SA
authors.lastname: Trauger
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Wenlong
authors.initials: W
authors.lastname: Han
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Ying
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037.
authors.forename: Mary O
authors.initials: MO
authors.lastname: Oyeleye
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093 and the Scripps Research Institute, La Jolla, California 92037. Electronic address: wdillmann@ucsd.edu.
authors.forename: Wolfgang H
authors.initials: WH
authors.lastname: Dillmann
mesh_terms: D000117:Acetylglucosamine / Q000235:genetics / Q000378:metabolism; D000818:Animals; D051545:Cyclooxygenase 1 / Q000378:metabolism; D003920:Diabetes Mellitus / Q000201:enzymology* / Q000473:pathology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D005964:Glucosyltransferases / Q000096:biosynthesis*; D006031:Glycosylation / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008929:Mitochondria, Heart / Q000201:enzymology* / Q000473:pathology; D024101:Mitochondrial Proteins / Q000096:biosynthesis*; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000473:pathology; D009245:NADH Dehydrogenase / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D051381:Rats; D013549:Sweetening Agents / Q000494:pharmacology*
chemical_list: D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D013549:Sweetening Agents; D051545:Cyclooxygenase 1; C496512:Ptgs1 protein, mouse; C496513:Ptgs1 protein, rat; D009245:NADH Dehydrogenase; D005964:Glucosyltransferases; D005947:Glucose; D000117:Acetylglucosamine