Bleomycin induces alveolar epithelial cell death through JNK-dependent activation of the mitochondrial death pathway.
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.
Lee
Vivian Y
VY
Div. of Pulmonary & Critical Care, Northwestern University, Chicago, IL 60611, USA.
Schroedl
Clara
C
Brunelle
Joslyn K
JK
Buccellato
Leonard J
LJ
Akinci
Ozkan I
OI
Kaneto
Hideaki
H
Snyder
Colleen
C
Eisenbart
James
J
Budinger
G R Scott
GR
Chandel
Navdeep S
NS
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051023:BH3 Interacting Domain Death Agonist Protein; D001761:Bleomycin / Q000494:pharmacology*; D002352:Carrier Proteins / Q000235:genetics; D002478:Cells, Cultured; D053200:Fas-Associated Death Domain Protein; D015870:Gene Expression; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D008817:Mice, Mutant Strains; D008928:Mitochondria / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D020545:Respiratory Mucosa / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
D048868:Adaptor Proteins, Signal Transducing; D000903:Antibiotics, Antineoplastic; D051023:BH3 Interacting Domain Death Agonist Protein; C494773:Bak1 protein, mouse; C494774:Bak1 protein, rat; C494827:Bax protein, mouse; C494828:Bax protein, rat; C494812:Bcl2l1 protein, mouse; C494813:Bcl2l1 protein, rat; C494815:Bid protein, mouse; C494816:Bid protein, rat; D002352:Carrier Proteins; C505534:Fadd protein, mouse; C505535:Fadd protein, rat; D053200:Fas-Associated Death Domain Protein; D008565:Membrane Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D001761:Bleomycin; D048031:JNK Mitogen-Activated Protein Kinases