Diabetes-associated dysregulation of O-GlcNAcylation in rat cardiac mitochondria.
Elevated mitochondrial O-GlcNAcylation caused by hyperglycemia, as occurs in diabetes, significantly contributes to mitochondrial dysfunction and to diabetic cardiomyopathy. However, little is known about the enzymology of mitochondrial O-GlcNAcylation. Herein, we investigated the enzymes responsible for cycling O-GlcNAc on mitochondrial proteins and studied the mitochondrial transport of UDP-GlcNAc. Analyses of purified rat heart mitochondria from normal and streptozocin-treated diabetic rats show increased mitochondrial O-GlcNAc transferase (OGT) and a concomitant decrease in the mito-specific O-GlcNAcase (OGA). Strikingly, OGT is mislocalized in cardiac mitochondria from diabetic rats. Interaction of OGT and complex IV observed in normal rat heart mitochondria is visibly reduced in diabetic samples, where OGT is mislocalized to the matrix. Live cell OGA activity assays establish the presence of O-GlcNAcase within the mitochondria. Furthermore, we establish that the inner mitochondrial membrane transporter, pyrimidine nucleotide carrier, transports UDP-GlcNAc from the cytosol to the inside of the mitochondria. Knockdown of this transporter substantially lowers mitochondrial O-GlcNAcylation. Inhibition of OGT or OGA activity within neonatal rat cardiomyocytes significantly affects energy production, mitochondrial membrane potential, and mitochondrial oxygen consumption. These data suggest that cardiac mitochondria not only have robust O-GlcNAc cycling, but also that dysregulation of O-GlcNAcylation likely plays a key role in mitochondrial dysfunction associated with diabetes.
Department of Biological Chemistry, The Johns Hopkins School of Medicine, Baltimore, MD 21205-2185.
Partha S
PS
Banerjee
Department of Biological Chemistry, The Johns Hopkins School of Medicine, Baltimore, MD 21205-2185.
Junfeng
J
Ma
Department of Biological Chemistry, The Johns Hopkins School of Medicine, Baltimore, MD 21205-2185 gwhart@jhmi.edu.
Gerald W
GW
Hart
D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D006596:Hexosaminidases / Q000378:metabolism; D020128:Inhibitory Concentration 50; D008247:Lysosomes / Q000378:metabolism; D008564:Membrane Potentials; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000378:metabolism; D008929:Mitochondria, Heart / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism*; D009711:Nucleotides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010101:Oxygen Consumption; D011485:Protein Binding; D011510:Proteolipids / Q000737:chemistry; D051381:Rats; D013385:Succinate Dehydrogenase / Q000378:metabolism
D045222:Electron Transport Chain Complex Proteins; D033681:Mitochondrial Membrane Transport Proteins; D009711:Nucleotides; D011510:Proteolipids; C020485:proteoliposomes; D000255:Adenosine Triphosphate; D013385:Succinate Dehydrogenase; D017351:N-Acetylglucosaminyltransferases; C449880:O-GlcNAc transferase; C063057:UDP-N-acetylglucosamine-peptide beta-N-acetylglucosaminyltransferase; D006596:Hexosaminidases; D010100:Oxygen
O-GlcNAc; O-GlcNAc transferase; diabetes; diabetic cardiomyopathy; mitochondria