title: Uncoupling protein-2 overexpression inhibits mitochondrial death pathway in cardiomyocytes.
abstract: Uncoupling proteins (UCPs) are located in the mitochondrial inner membrane and partially dissipate the transmembrane proton electrochemical gradient. UCP2 is expressed in various human and rodent tissues, including the heart, where its functional role is unknown. In the present study, we tested the hypothesis that UCP2 overexpression could protect cardiomyocytes from oxidative stress-induced cell death by reducing reactive oxygen species (ROS) production in mitochondria. Using an adenoviral vector containing human UCP2, we investigated the effects of UCP2 overexpression on the mitochondrial death pathway induced by oxidative stress (100 micromol/L H2O2) in cultured neonatal cardiomyocytes. UCP2 overexpression significantly suppressed markers of cell death, including TUNEL positivity, phosphatidylserine exposure, propidium iodide uptake, and caspase-3 cleavage. Furthermore, UCP2 remarkably prevented the catastrophic loss of mitochondrial inner membrane potential induced by H2O2, which is a critical early event in cell death. Ca2+ overload and the production of ROS in mitochondria, both of which contribute to mitochondrial inner membrane potential loss, were dramatically attenuated by UCP2 overexpression. Thus, overexpression of UCP2 attenuates ROS generation and prevents mitochondrial Ca2+ overload, revealing a novel mechanism of cardioprotection.
authors.affiliation: Institute of Molecular Cardiobiology, The Johns Hopkins University, Baltimore, Md 21205, USA.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Teshima
authors.forename: Masaharu
authors.initials: M
authors.lastname: Akao
authors.forename: Steven P
authors.initials: SP
authors.lastname: Jones
authors.forename: Eduardo
authors.initials: E
authors.lastname: Marbán
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D005456:Fluorescent Dyes / Q000378:metabolism; D015870:Gene Expression; D018014:Gene Transfer Techniques; D006801:Humans; D020287:In Situ Nick-End Labeling; D007473:Ion Channels; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D026901:Membrane Transport Proteins; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D024101:Mitochondrial Proteins; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D010718:Phosphatidylserines / Q000378:metabolism; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D000071246:Uncoupling Protein 2
chemical_list: D005456:Fluorescent Dyes; D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D016877:Oxidants; D010718:Phosphatidylserines; D011506:Proteins; D017382:Reactive Oxygen Species; C000604389:UCP2 protein, human; C000604391:Ucp2 protein, rat; D000071246:Uncoupling Protein 2; C505407:CASP3 protein, human; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases