title: Mitochondria protection from hypoxia/reoxygenation injury with mitochondria heat shock protein 70 overexpression.
abstract: The majority of mitochondrial proteins are encoded by nuclear genes and synthesized in the cytosol as preproteins containing a mitochondria import sequence. Preproteins traverse the outer mitochondrial membrane in an unfolded state and then translocate through the inner membrane into the matrix via import machinery that includes mitochondrial heat shock protein 70 (mtHSP70). Neonatal rat cardiac myocytes (NCM) infected with an adenoviral vector expressing mtHSP70 or an empty control (Adv(-)) for 48 h were submitted to 8 h of simulated ischemia (hypoxia) followed by 16 h of reperfusion (reoxygenation). Infection with mtHSP70 virus yielded an increase in mtHSP70 protein in NCM mitochondria compared with Adv(-) (P < 0.05). Cell viability after simulated ischemia/reperfusion (I/R) was decreased in both Adv(-) and mtHSP70 groups, relative to control (P < 0.05), but mtHSP70-infected NCM had enhanced viability after I/R relative to Adv-infected NCM (P < 0.05). Simulated I/R caused an increase in reactive oxygen species generation and lipid peroxidation in Adv-infected NCM (P < 0.05, for both) that was not observed in mtHSP70-infected NCM. Mitochondrial complex III and IV activities were greater in mtHSP70-infected NCM after simulated I/R compared with Adv(-) (P < 0.05 for both). After simulated I/R, ATP content increased in mtHSP70-infected NCM, compared with Adv(-) (P < 0.05). Apoptotic markers were decreased in mtHSP70-infected NCM compared with Adv(-) after simulated I/R (P < 0.05). These results indicate that overexpression of mtHSP70 protects the mitochondria against damage from simulated I/R that may be due to a decrease in reactive oxygen species leading to preservation of mitochondrial complex function activities and ATP formation.
authors.affiliation: West Virginia University School of Medicine, Division of Exercise Physiology, Center for Interdisciplinary Research in Cardiovascular Sciences, 1 Medical Center Drive, Morgantown, WV 26506, USA.
authors.forename: Courtney L
authors.initials: CL
authors.lastname: Williamson
authors.forename: Erinne R
authors.initials: ER
authors.lastname: Dabkowski
authors.forename: Wolfgang H
authors.initials: WH
authors.lastname: Dillmann
authors.forename: John M
authors.initials: JM
authors.lastname: Hollander
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D015153:Blotting, Western; D015687:Cell Hypoxia; D002470:Cell Survival; D002478:Cells, Cultured; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D005822:Genetic Vectors; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D015227:Lipid Peroxidation; D008929:Mitochondria, Heart / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation
chemical_list: D018840:HSP70 Heat-Shock Proteins; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III