Bleomycin induces alveolar epithelial cell death through JNK-dependent activation of the mitochondrial death pathway

• Published in: American journal of physiology. Lung cellular and molecular physiology 2005-10, Vol.289 (4), p.L521-L528
• Main Authors: Lee, Vivian Y, Schroedl, Clara, Brunelle, Joslyn K, Buccellato, Leonard J, Akinci, Ozkan I, Kaneto, Hideaki, Snyder, Colleen, Eisenbart, James, Budinger, G. R. Scott, Chandel, Navdeep S
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adenovirus; Animals; Antibiotics, Antineoplastic - pharmacology; Apoptosis - drug effects; Apoptosis - physiology; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; bcl-X Protein; BH3 Interacting Domain Death Agonist Protein; Bleomycin - pharmacology; Carrier Proteins - genetics; Cells, Cultured; Fas-Associated Death Domain Protein; Gene Expression; JNK Mitogen-Activated Protein Kinases - genetics; JNK Mitogen-Activated Protein Kinases - metabolism; Membrane Proteins - genetics; Mice; Mice, Mutant Strains; Mitochondria - metabolism; Proto-Oncogene Proteins c-bcl-2 - genetics; Proto-Oncogene Proteins c-bcl-2 - metabolism; Pulmonary Alveoli - cytology; Pulmonary Alveoli - drug effects; Pulmonary Alveoli - enzymology; Rats; Respiratory Mucosa - cytology; Respiratory Mucosa - drug effects; Respiratory Mucosa - enzymology
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.00340.2004

1 Division of Pulmonary & Critical Care Medicine, Department of Medicine, Northwestern University, Chicago, Illinois; and 2 Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Osaka, Japan Submitted 14 September 2004 ; accepted in final form 27 April 2005 Exposure to bleomycin in rodents induces lung injury and fibrosis. Alveolar epithelial cell death has been hypothesized as an initiating mechanism underlying bleomycin-induced lung injury and fibrosis. In the present study we evaluated the contribution of mitochondrial and receptor-meditated death pathways in bleomycin-induced death of mouse alveolar epithelial cells (MLE-12 cells) and primary rat alveolar type II cells. Control MLE-12 cells and primary rat alveolar type II cells died after 48 h of exposure to bleomycin. Both MLE-12 cells and rat alveolar type II cells overexpressing Bcl-X L did not undergo cell death in response to bleomycin. Dominant negative Fas-associating protein with a death domain failed to prevent bleomycin-induced cell death in MLE-12 cells. Caspase-8 inhibitor CrmA did not prevent bleomycin-induced cell death in primary rat alveolar type II cells. Furthermore, fibroblast cells deficient in Bax and Bak, but not Bid, were resistant to bleomycin-induced cell death. To determine whether the stress kinase JNK was an upstream regulator of Bax activation, MLE-12 cells were exposed to bleomycin in the presence of an adenovirus encoding a dominant negative JNK. Bleomycin-induced Bax activation was prevented by the expression of a dominant negative JNK in MLE-12 cells. Dominant negative JNK prevented cell death in MLE-12 cells and in primary rat alveolar type II cells exposed to bleomycin. These data indicate that bleomycin induces cell death through a JNK-dependent mitochondrial death pathway in alveolar epithelial cells. Bax; c-Jun NH 2 -terminal kinase; apoptosis; lung; fibrosis Address for reprint requests and other correspondence: N. S. Chandel, Div. of Pulmonary & Critical Care, 240 E. Huron, 2nd Fl., Chicago, IL 60611 (e-mail: nav{at}northwestern.edu )