Journal article
Effect of the Mitochondrial Transaminase (GOT2) on Membrane Potential Sensitive Respiration in Mitochondria of Differentiated C2C12 Muscle Cells
American Journal of Physiology: Cell Physiology, Vol.326(6), pp.C1669-C1682
04/22/2024
DOI: 10.1152/ajpcell.00576.2023
PMCID: PMC11371315
PMID: 38646781
Abstract
We previously showed that the transaminase inhibitor, aminooxyacetic acid, reduced respiration energized at complex II (succinate dehydrogenase, SDH) in mitochondria isolated from mouse hindlimb muscle. The effect required a reduction in membrane potential with resultant accumulation of oxaloacetate (OAA), a potent inhibitor of SDH. To specifically assess the effect of the mitochondrial transaminase, glutamic oxaloacetic transaminase (GOT2) on complex II respiration and to determine the effect in intact cells as well as isolated mitochondria, we performed respiratory and metabolic studies in wildtype (WT) and CRISPR-generated GOT2 knockdown (KD) C2C12 myocytes. Intact cell respiration by GOT2KD cells versus WT was reduced by adding carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP) to lower potential. In mitochondria of C2C12 KD cells, respiration at low potential generated by 1µM FCCP and energized at complex II by 10mM succinate + 0.5mM glutamate, (but not by complex I substrates) was reduced versus WT mitochondria. Although we could not detect OAA, metabolite data suggested that OAA inhibition of SDH may have contributed to the FCCP effect. C2C12 mitochondria differed from skeletal muscle mitochondria in that the effect of FCCP on complex II respiration was not evident with ADP addition. We also observed that C2C12 cells, unlike skeletal muscle, expressed glutamate dehydrogenase, which competes with GOT2 for glutamate metabolism. In summary, GOT2 KD reduced C2C12 respiration in intact cells at low potential. From differential substrate effects, this occurred largely at complex II. Moreover, C2C12 versus muscle mitochondria differ in complex II sensitivity to ADP and differ markedly in expression of glutamate dehydrogenase.
Details
- Title: Subtitle
- Effect of the Mitochondrial Transaminase (GOT2) on Membrane Potential Sensitive Respiration in Mitochondria of Differentiated C2C12 Muscle Cells
- Creators
- Ritu Som - University of Iowa, Internal MedicineBrian D Fink - University of Iowa, Internal MedicineLiping Yu - University of Iowa, Medicine AdministrationWilliam I Sivitz - University of Iowa, Endocrinology and Metabolism
- Resource Type
- Journal article
- Publication Details
- American Journal of Physiology: Cell Physiology, Vol.326(6), pp.C1669-C1682
- DOI
- 10.1152/ajpcell.00576.2023
- PMID
- 38646781
- PMCID
- PMC11371315
- NLM abbreviation
- Am J Physiol Cell Physiol
- eISSN
- 1522-1563
- Grant note
- Iowa Fraternal Order of the Eagles 1 R01 DK123043-01A1 / HHS | NIH | National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) 2 I01 BX000285-06 / U.S. Department of Veterans Affairs (VA)
- Language
- English
- Electronic publication date
- 04/22/2024
- Academic Unit
- Fraternal Order of Eagles Diabetes Research Center; Biochemistry and Molecular Biology; Medicine Administration; Endocrinology and Metabolism; Internal Medicine
- Record Identifier
- 9984621758702771
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