Evidence that tumor necrosis factor triggers apoptosis in human endothelial cells by interleukin-1-converting enzyme-like protease-dependent and -independent pathways.
Cultured human endothelial cells (EC) resist tumor necrosis factor (TNF)-mediated apoptosis. However, the combination of TNF and the protein synthesis inhibitor cycloheximide (CHX) induces apoptosis in up to 50% of EC within 24 hours. TNF + CHX killing is effectively blocked by transfected CrmA protein or treatment with Z-VAD.fmk peptide-both inhibitors of interleukin-1-converting enzyme-like proteases-but not by transfected antiapoptotic proteins Bcl-2, Bcl-XL, or A1. C6-ceramide (cer) can also sensitize EC to TNF-induced apoptosis. TNF + cer killing, which can affect more than 50% of EC, is not effectively inhibited by CrmA or Z-VAD frank, but can be readily blocked by Bcl-2, Bcl-XL, or A1. Both TNF + CHX and TNF+ cer killing are induced by a TNF mutein that only interacts with the type 1 TNF receptor, and both responses can be inhibited by the antiapoptotic protein A20. These data suggest that TNF activates two biochemically separable pathways of EC injury.
Slowik
M R
MR
Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536-0812, USA.
Min
W
W
Ardito
T
T
Karsan
A
A
Kashgarian
M
M
Pober
J S
JS
D017209:Apoptosis / Q000502:physiology*; D020170:Caspase 1; D002478:Cells, Cultured; D002518:Ceramides / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000502:physiology*; D004351:Drug Resistance; D010450:Endopeptidases / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D008854:Microscopy, Electron; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002518:Ceramides; D011500:Protein Synthesis Inhibitors; D014409:Tumor Necrosis Factor-alpha; D003513:Cycloheximide; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D020170:Caspase 1