Regulation of mitochondrial aconitase by phosphorylation in diabetic rat heart.
Mitochondrial dysfunction and protein kinase C (PKC) activation are consistently found in diabetic cardiomyopathy but their relationship remains unclear. This study identified mitochondrial aconitase as a downstream target of PKC activation using immunoblotting and mass spectrometry, and then characterized phosphorylation-induced changes in its activity in hearts from type 1 diabetic rats. PKCbeta(2) co-immunoprecipitated with phosphorylated aconitase from mitochondria isolated from diabetic hearts. Augmented phosphorylation of mitochondrial aconitase in diabetic hearts was found to be associated with an increase in its reverse activity (isocitrate to aconitate), while the rate of the forward activity was unchanged. Similar results were obtained on phosphorylation of mitochondrial aconitase by PKCbeta(2) in vitro. These results demonstrate the regulation of mitochondrial aconitase activity by PKC-dependent phosphorylation. This may influence the activity of the tricarboxylic acid cycle, and contribute to impaired mitochondrial function and energy metabolism in diabetic hearts.
Lin
G
G
Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3, Canada.
Brownsey
R W
RW
MacLeod
K M
KM
D001275:ATP Citrate (pro-S)-Lyase / Q000378:metabolism; D000154:Aconitate Hydratase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002952:Citric Acid Cycle / Q000502:physiology; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology* / Q000648:ultrastructure; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology
D007527:Isoenzymes; D001275:ATP Citrate (pro-S)-Lyase; D011493:Protein Kinase C; D000154:Aconitate Hydratase