Mitochondrial localization and function of heme oxygenase-1 in cigarette smoke-induced cell death

Am J Respir Cell Mol Biol. 2007 Apr;36(4):409-17. doi: 10.1165/rcmb.2006-0214OC. Epub 2006 Nov 1.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / deficiency
  • Animals
  • Cell Death
  • Cell Line
  • Epithelial Cells / drug effects
  • Gene Expression Regulation, Enzymologic*
  • Heme Oxygenase-1 / metabolism*
  • Heme Oxygenase-1 / physiology
  • Humans
  • Lung / cytology
  • Lung / drug effects*
  • Male
  • Membrane Potential, Mitochondrial
  • Mice
  • Mice, Inbred AKR
  • Mitochondria / drug effects
  • Mitochondria / enzymology*
  • Respiratory Mucosa / cytology
  • Respiratory Mucosa / enzymology
  • Respiratory Mucosa / ultrastructure
  • Smoke / adverse effects*
  • Transfection
  • Up-Regulation

Substances

  • Smoke
  • Adenosine Triphosphate
  • Heme Oxygenase-1