Glutathione Levels and BAX Activation during Apoptosis Due to Oxidative Stress in Cells Expressing Wild-type and Mutant Cystic Fibrosis Transmembrane Conductance Regulator

• Published in: The Journal of biological chemistry Vol. 277; no. 31; pp. 27912 - 27918
• Main Authors: Jungas, Thomas, Motta, Iris, Duffieux, Francis, Fanen, Pascale, Stoven, Véronique, Ojcius, David M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02.08.2002; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Substitution; Apoptosis - drug effects; Apoptosis - physiology; bcl-2-Associated X Protein; Buthionine Sulfoximine - pharmacology; Cystic Fibrosis Transmembrane Conductance Regulator - genetics; Cystic Fibrosis Transmembrane Conductance Regulator - physiology; Glutathione - metabolism; HeLa Cells; Humans; Hydrogen Peroxide - pharmacology; Kinetics; Life Sciences; Mutagenesis; Oxidative Stress - drug effects; Oxidative Stress - physiology; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-bcl-2; Respiratory Mucosa - cytology; Respiratory Mucosa - physiology; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110288200

Cystic fibrosis is characterized by chronic inflammation and an imbalance in the concentrations of alveolar and lung oxidants and antioxidants, which result in cell damage. Modifications in lung glutathione concentrations are recognized as a salient feature of inflammatory lung diseases such as cystic fibrosis, and glutathione plays a major role in protection against oxidative stress and is important in modulation of apoptosis. The cystic fibrosis transmembrane conductance regulator (CFTR) is permeable to Cl−, larger organic ions, and reduced and oxidized forms of glutathione, and the ΔF508 CFTR mutation found in cystic fibrosis patients has been correlated with impaired glutathione transport in cystic fibrosis airway epithelia. Because intracellular glutathione protects against oxidative stress-induced apoptosis, we studied the susceptibility of epithelial cells (HeLa and IB3–1) expressing normal and mutant CFTR to apoptosis triggered by H2O2. We find that cells with normal CFTR are more sensitive to oxidative stress-induced apoptosis than cells expressing defective CFTR. In addition, sensitivity to apoptosis could be correlated with glutathione levels, because depletion of intracellular glutathione results in higher levels of apoptosis, and glutathione levels decreased faster in cells expressing normal CFTR than in cells with defective CFTR during incubation with H2O2. The pro-apoptotic BCL-2 family member, BAX, is also activated faster in cells expressing normal CFTR than in those with mutant CFTR under these conditions, and artificial glutathione depletion increases the extent of BAX activation. These results suggest that glutathione-dependent BAX activation in cells with normal CFTR represents an early step in oxidative stress-induced apoptosis of these cells.