Menadione triggers cell death through ROS-dependent mechanisms involving PARP activation without requiring apoptosis

Low levels of reactive oxygen species (ROS) can function as redox active signaling messengers whereas high levels of ROS induce cellular damage Menadione generates ROS through redox cycling and high concentrations trigger cell death Previous work suggests that menadione triggers cytochrome c release from mitochondria whereas other studies implicate the activation of the mitochondrial permeability transition pore as the mediator of cell death We investigated menadione induced cell death in genetically modified cells lacking specific death-associated proteins In cardiomyocytes oxidant stress was assessed using the redox sensor RoGFP expressed in the cytosol or the mitochondria! matrix Menadione elicited rapid oxidation in both compartments whereas it decreased mitochondrial potential and triggered cytochrome c redistribution to the cytosol Cell death was attenuated by N-acetylcysteine and exogenous glutathione or by overexpression of cytosolic or mitochondria-targeted catalase By contrast no protection was observed in cells overexpressing Cu Zn SOD or Mn-SOD Overexpression of antiapoptotic Bcl-X-L protected against staurosporine induced cell death but it failed to confer protection against menadione Genetic deletion of Bax and Bak cytochrome c cyclophilin D or caspase 9 conferred no protection against menadione-induced cell death However cells lacking PARP-1 showed a significant decrease in menadione-induced cell death Thus menadione induces cell death through the generation of oxidant stress in multiple subcellular compartments yet cytochrome c Bax/Bak caspase-9 and cyclophilin D are dispensable for cell death in this model These studies suggest that multiple redundant cell death pathways are activated by menadione but that PARP plays an essential role in mediating each of them (C) 2010 Elsevier Inc All rights reserved