title: Complex I dysfunction underlies the glycolytic switch in pulmonary hypertensive smooth muscle cells.
abstract: ATP is essential for cellular function and is usually produced through oxidative phosphorylation. However, mitochondrial dysfunction is now being recognized as an important contributing factor in the development cardiovascular diseases, such as pulmonary hypertension (PH). In PH there is a metabolic change from oxidative phosphorylation to mainly glycolysis for energy production. However, the mechanisms underlying this glycolytic switch are only poorly understood. In particular the role of the respiratory Complexes in the mitochondrial dysfunction associated with PH is unresolved and was the focus of our investigations. We report that smooth muscle cells isolated from the pulmonary vessels of rats with PH (PH-PASMC), induced by a single injection of monocrotaline, have attenuated mitochondrial function and enhanced glycolysis. Further, utilizing a novel live cell assay, we were able to demonstrate that the mitochondrial dysfunction in PH-PASMC correlates with deficiencies in the activities of Complexes I-III. Further, we observed that there was an increase in mitochondrial reactive oxygen species generation and mitochondrial membrane potential in the PASMC isolated from rats with PH. We further found that the defect in Complex I activity was due to a loss of Complex I assembly, although the assembly of Complexes II and III were both maintained. Thus, we conclude that loss of Complex I assembly may be involved in the switch of energy metabolism in smooth muscle cells to glycolysis and that maintaining Complex I activity may be a potential therapeutic target for the treatment of PH.
authors: Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, AZ, USA; Department of Medicine, The University of Arizona, Tucson, AZ, USA. Electronic address: ruslanrafikov@deptofmed.arizona.edu.
authors: Ruslan
authors: R
authors: Rafikov
authors: Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, AZ, USA; Department of Medicine, The University of Arizona, Tucson, AZ, USA.
authors: Xutong
authors: X
authors: Sun
authors: Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, AZ, USA; Department of Medicine, The University of Arizona, Tucson, AZ, USA.
authors: Olga
authors: O
authors: Rafikova
authors: Vascular Biology Center, Georgia Regents University, Augusta, GA, USA.
authors: Mary
authors: M
authors: Louise Meadows
authors: Department of Medicine, The University of Arizona, Tucson, AZ, USA.
authors: Ankit A
authors: AA
authors: Desai
authors: Department of Surgery, The University of Arizona, Tucson, AZ, USA.
authors: Zain
authors: Z
authors: Khalpey
authors: Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, AZ, USA; Department of Medicine, The University of Arizona, Tucson, AZ, USA.
authors: Jason X-J
authors: JX
authors: Yuan
authors: Department of Pediatrics and the University of California San Francisco, San Francisco, CA, USA; Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA.
authors: Jeffrey R
authors: JR
authors: Fineman
authors: Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, AZ, USA; Department of Medicine, The University of Arizona, Tucson, AZ, USA. Electronic address: steveblack@email.arizona.edu.
authors: Stephen M
authors: SM
authors: Black
mesh_terms: D000818:Animals; D004579:Electron Transport / Q000235:genetics; D042967:Electron Transport Complex I / Q000172:deficiency / Q000235:genetics*; D042963:Electron Transport Complex II / Q000235:genetics / Q000378:metabolism; D014450:Electron Transport Complex III / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006019:Glycolysis / Q000235:genetics*; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D008168:Lung / Q000098:blood supply / Q000473:pathology; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D016686:Monocrotaline; D032389:Myocytes, Smooth Muscle / Q000201:enzymology* / Q000473:pathology; D010085:Oxidative Phosphorylation; D061251:Primary Cell Culture; D011651:Pulmonary Artery / Q000201:enzymology* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D016686:Monocrotaline; D042963:Electron Transport Complex II; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III
keywords: Electron transport chain; Mitochondria; Pulmonary hypertension; Warburg effect