title: ROS-mediated PARP activity undermines mitochondrial function after permeability transition pore opening during myocardial ischemia-reperfusion.
abstract: BACKGROUND
  Ischemia-reperfusion (I/R) studies have implicated oxidant stress, the mitochondrial permeability transition pore (mPTP), and poly(ADP-ribose) polymerase (PARP) as contributing factors in myocardial cell death. However, the interdependence of these factors in the intact, blood-perfused heart is not known. We therefore wanted to determine whether oxidant stress, mPTP opening, and PARP activity contribute to the same death pathway after myocardial I/R.
  
  
  RESULTS
  A murine left anterior descending coronary artery (LAD) occlusion (30 minutes) and release (1 to 4 hours) model was employed. Experimental groups included controls and antioxidant-treated, mPTP-inhibited, or PARP-inhibited hearts. Antioxidant treatment prevented oxidative damage, mPTP opening, ATP depletion, and PARP activity, placing oxidant stress as the proximal death trigger. Genetic deletion of cyclophilin D (CypD(-/-)) prevented loss of total NAD(+) and PARP activity, and mPTP-mediated loss of mitochondrial function. Control hearts showed progressive mitochondrial depolarization and loss of ATP from 1.5 to 4 hours of reperfusion, but not outer mitochondrial membrane rupture. Neither genetic deletion of PARP-1 nor its pharmacological inhibition prevented the initial mPTP-mediated depolarization or loss of ATP, but PARP ablation did allow mitochondrial recovery by 4 hours of reperfusion.
  
  
  CONCLUSIONS
  These results indicate that oxidant stress, the mPTP, and PARP activity contribute to a single death pathway after I/R in the heart. PARP activation undermines cell survival by preventing mitochondrial recovery after mPTP opening early in reperfusion. This suggests that PARP-mediated prolongation of mitochondrial depolarization contributes significantly to cell death via an energetic crisis rather than by mitochondrial outer membrane rupture.
authors.affiliation: Division of Neonatology, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Schriewer
authors.forename: Clara Bien
authors.initials: CB
authors.lastname: Peek
authors.forename: Joseph
authors.initials: J
authors.lastname: Bass
authors.forename: Paul T
authors.initials: PT
authors.lastname: Schumacker
mesh_terms: D000818:Animals; D016923:Cell Death; D002470:Cell Survival; D021983:Cyclophilins / Q000235:genetics; D004195:Disease Models, Animal; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D008929:Mitochondria, Heart / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000502:physiology*; D051336:Mitochondrial Membranes / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D017202:Myocardial Ischemia / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D015428:Myocardial Reperfusion Injury / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D018384:Oxidative Stress / Q000502:physiology*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D017382:Reactive Oxygen Species; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D021983:Cyclophilins