The intrinsic apoptotic pathway is required for lipopolysaccharide-induced lung endothelial cell death.
LPS has been implicated in the pathogenesis of endothelial cell death associated with Gram-negative bacterial sepsis. The binding of LPS to the TLR-4 on the surface of endothelial cells initiates the formation of a death-inducing signaling complex at the cell surface. The subsequent signaling pathways that result in apoptotic cell death remain unclear and may differ among endothelial cells in different organs. We sought to determine whether LPS and cycloheximide-induced cell death in human lung microvascular endothelial cells (HmVECs) was dependent upon activation of the intrinsic apoptotic pathway and the generation of reactive oxygen species. We found that cells overexpressing the anti-apoptotic protein Bcl-X(L) were resistant to LPS and cycloheximide-induced death and that the proapoptotic Bcl-2 protein Bid was cleaved following treatment with LPS. The importance of Bid was confirmed by protection of Bid-deficient (bid(-/-)) mice from LPS-induced lung injury. Neither HmVECs treated with the combined superoxide dismutase/catalase mimetic EUK-134 nor HmVECs depleted of mitochondrial DNA (rho(0) cells) were protected against LPS and cycloheximide-induced death. We conclude that LPS and cycloheximide-induced death in HmVECs requires the intrinsic cell death pathway, but not the generation of reactive oxygen species.
Wang
Helena L
HL
Division of Pulmonary and Critical Care Medicine, Loyola University, Maywood, Illinois 60153, USA.
Akinci
I Ozkan
IO
Baker
Christina M
CM
Urich
Daniela
D
Bellmeyer
Amy
A
Jain
Manu
M
Chandel
Navdeep S
NS
Mutlu
Gökhan M
GM
Budinger
G R Scott
GR
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004338:Drug Combinations; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D008168:Lung / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000276:immunology*
D051023:BH3 Interacting Domain Death Agonist Protein; C494815:Bid protein, mouse; D004338:Drug Combinations; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D003513:Cycloheximide