Mitochondrial localization and function of heme oxygenase-1 in cigarette smoke-induced cell death.
Cigarette smoke-induced apoptosis and necrosis contribute to the pathogenesis of chronic obstructive pulmonary disease. The induction of heme oxygenase-1 provides cytoprotection against oxidative stress, and may protect in smoking-related disease. Since mitochondria regulate cellular death, we examined the functional expression and mitochondrial localization of heme oxygenase-1 in pulmonary epithelial cells exposed to cigarette smoke extract (CSE), and its role in modulating cell death. Heme oxygenase-1 expression increased dramatically in cytosolic and mitochondrial fractions of human alveolar (A549), or bronchial epithelial cells (Beas-2b) exposed to either hemin, lipopolysaccharide, or CSE. Mitochondrial localization of heme oxygenase-1 was also observed in a primary culture of human small airway epithelial cells. Furthermore, heme oxygenase activity increased dramatically in mitochondrial fractions, and in whole cell extracts of Beas-2b after exposure to hemin and CSE. The mitochondrial localization of heme oxygenase-1 in Beas-2b was confirmed using immunogold-electron microscopy and immunofluorescence labeling on confocal laser microscopy. CSE caused loss of cellular ATP and rapid depolarization of mitochondrial membrane potential. Apoptosis occurred in Beas-2b at low concentrations of cigarette smoke extract, whereas necrosis occurred at high concentrations. Overexpression of heme oxygenase-1 inhibited CSE-induced Beas-2b cell death and preserved cellular ATP levels. Finally, heme oxygenase-1 mRNA expression was elevated in the lungs of mice chronically exposed to cigarette smoke. We demonstrate the functional compartmentalization of heme oxygenase-1 in the mitochondria of lung epithelial cells, and its potential role in defense against mitochondria-mediated cell death during CSE exposure.
Slebos
Dirk-Jan
DJ
Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, MUH 628NW, 3459 Fifth Ave., Pittsburgh, PA 15213, USA.
Ryter
Stefan W
SW
van der Toorn
Marco
M
Liu
Fang
F
Guo
Fengli
F
Baty
Catherine J
CJ
Karlsson
Jenny M
JM
Watkins
Simon C
SC
Kim
Hong Pyo
HP
Wang
Xue
X
Lee
Janet S
JS
Postma
Dirkje S
DS
Kauffman
Henk F
HF
Choi
Augustine M K
AM
D000255:Adenosine Triphosphate / Q000172:deficiency; D000818:Animals; D016923:Cell Death; D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic; D051547:Heme Oxygenase-1 / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D008168:Lung / Q000166:cytology / Q000187:drug effects*; D008297:Male; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D008806:Mice, Inbred AKR; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D020545:Respiratory Mucosa / Q000166:cytology / Q000201:enzymology / Q000648:ultrastructure; D012906:Smoke / Q000009:adverse effects*; D014162:Transfection; D015854:Up-Regulation
D012906:Smoke; D000255:Adenosine Triphosphate; D051547:Heme Oxygenase-1