Submitted on July 13, 2005
Accepted on December 21, 2005
Mitochondrial Localization of Catalase Provides Optimal Protection from H2O2-Induced Cell Death in Lung Epithelial Cells
Yuko Arita1, S. Hella Harkness2, Jeffrey A Kazzaz1, Hshi-chi Koo2, Ansamma Joseph3, J. Andres Melendez4, Jonathan M Davis2, A Chander5, and Yuchi Li3*
1 CardioPulmonary Research Institute, Winthrop-University Hospital; SUNY Stony Brook School of Medicine, Mineola, NY, USA; Department of Medicine, Winthrop-University Hospital; SUNY Stony Brook School of Medicine, Mineola, NY, USA
2 CardioPulmonary Research Institute, Winthrop-University Hospital; SUNY Stony Brook School of Medicine, Mineola, NY, USA; Department of Pediatrics, Winthrop-University Hospital; SUNY Stony Brook School of Medicine, Mineola, NY, USA
3 CardioPulmonary Research Institute, Winthrop-University Hospital; SUNY Stony Brook School of Medicine, Mineola, NY, USA; Thorocic-Cardiovascular Surgery, Winthrop-University Hospital; SUNY Stony Brook School of Medicine, Mineola, NY, USA
4 Center for Immunology & Microbial Disease, Albany Medical College, Albany, NY, USA
5 Department of Pediatrics, SUNY, University Hospital, Stony Brook, NY, USA
* To whom correspondence should be addressed. E-mail: yli{at}pulmonary.winthrop.org.
Reactive oxygen species (ROS) can cause cell injury and death via mitochondrial dependent pathways and supplementation with antioxidants has been shown to ameliorate these processes. c-Jun N-terminal kinase (JNK) pathway has been shown to play a critical role in ROS-induced cell death. To determine if targeting catalase (CAT) to the mitochondria provides better protection than cytosolic expression against H2O2-induced injury, two approaches were taken: 1) adenoviral mediated transduction was performed using cytosolic (CCAT) or mitochondrial (MCAT) CAT cDNAs; 2) stable cell lines were generated overexpressing CAT in mitochondria (n=3). Cells were exposed to 250 µM H2O2 and cell survival, mitochondrial function, cytochrome c (cyt c) release, and JNK activity were analyzed. Although all viral transduced cells had a transient 2-fold increase in CAT activity, MCAT cells had significantly higher survival rates, the best mitochondrial function and lowest JNK activity compared to CCAT and LacZ controls. The improved protection with MCAT was observed in primary type II lung epithelial cells as well as in transformed lung epithelial cells. In the three stable cell lines, cell survival directly correlated with extent of mitochondrial localization (r= 0.60572, P<0.05) and not overall CAT activity (r= -0.45501, P<0.05). Data indicate that targeting of antioxidants directly to the mitochondria is more effective in protecting lung epithelial cells against ROS-induced injury. This has important implications in antioxidant supplementation trials to prevent ROS-induced lung injury in critically ill patients.
