Abstract
In the presence of cycloheximide, tumor necrosis factor or interleukin-1 initiates caspase activation, loss of mitochondrial membrane potential (Δψ), DNA degradation, and nuclear condensation and fragmentation characteristic of apoptotic cell death in human vascular endothelial cells (EC). Inhibition of phosphatidylinositol 3-kinase (PI3K) by LY294002, but not inhibition of Akt by dominant-negative mutation, also sensitizes EC to cytokine-initiated apoptosis. Cytokine-initiated caspase activation is slower and comparatively less with LY294002 than with cycloheximide. Cycloheximide but not LY294002 decreases expression of c-FLIP (cellular FLICE inhibitory protein), an inhibitor of caspase-8 activation. The caspase inhibitor zVADfmk completely blocks caspase activation, DNA degradation, and nuclear fragmentation in both cases but only prevents loss of Δψ and cell death for cytokine plus cycloheximide treatment. In contrast, overexpression of Bcl-2 protects EC treated with cytokine plus LY294002 but not EC treated with cytokine plus cycloheximide. The cathepsin B inhibitor CA-074-Me prevents loss of Δψ, caspase activation, and cell death for EC treated with cytokine plus LY294002 but has no effect on EC treated with cytokine plus cycloheximide. Cathepsin B translocates from lysosomes to cytosol following treatment with LY294002 prior to the activation of caspases. These results suggest that inhibition of PI3K allows cytokines to activate a cathepsin-dependent, mitochondrial death pathway in which caspase activation is secondary, is not inhibited by c-FLIP, and is not essential for cell death.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 21295-21306 |
| Number of pages | 12 |
| Journal | Journal of Biological Chemistry |
| Volume | 278 |
| Issue number | 23 |
| DOIs | |
| State | Published - Jun 6 2003 |
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ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology
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Inhibition of phosphatidylinositol 3-kinase sensitizes vascular endothelial cells to cytokine-initiated cathepsin-dependent apoptosis. / Madge, Lisa A.; Li, Jie Hui; Choi, Jaehyuk; Pober, Jordan S.
In: Journal of Biological Chemistry, Vol. 278, No. 23, 06.06.2003, p. 21295-21306.Research output: Contribution to journal › Article
TY - JOUR
T1 - Inhibition of phosphatidylinositol 3-kinase sensitizes vascular endothelial cells to cytokine-initiated cathepsin-dependent apoptosis
AU - Madge, Lisa A.
AU - Li, Jie Hui
AU - Choi, Jaehyuk
AU - Pober, Jordan S.
PY - 2003/6/6
Y1 - 2003/6/6
N2 - In the presence of cycloheximide, tumor necrosis factor or interleukin-1 initiates caspase activation, loss of mitochondrial membrane potential (Δψ), DNA degradation, and nuclear condensation and fragmentation characteristic of apoptotic cell death in human vascular endothelial cells (EC). Inhibition of phosphatidylinositol 3-kinase (PI3K) by LY294002, but not inhibition of Akt by dominant-negative mutation, also sensitizes EC to cytokine-initiated apoptosis. Cytokine-initiated caspase activation is slower and comparatively less with LY294002 than with cycloheximide. Cycloheximide but not LY294002 decreases expression of c-FLIP (cellular FLICE inhibitory protein), an inhibitor of caspase-8 activation. The caspase inhibitor zVADfmk completely blocks caspase activation, DNA degradation, and nuclear fragmentation in both cases but only prevents loss of Δψ and cell death for cytokine plus cycloheximide treatment. In contrast, overexpression of Bcl-2 protects EC treated with cytokine plus LY294002 but not EC treated with cytokine plus cycloheximide. The cathepsin B inhibitor CA-074-Me prevents loss of Δψ, caspase activation, and cell death for EC treated with cytokine plus LY294002 but has no effect on EC treated with cytokine plus cycloheximide. Cathepsin B translocates from lysosomes to cytosol following treatment with LY294002 prior to the activation of caspases. These results suggest that inhibition of PI3K allows cytokines to activate a cathepsin-dependent, mitochondrial death pathway in which caspase activation is secondary, is not inhibited by c-FLIP, and is not essential for cell death.
AB - In the presence of cycloheximide, tumor necrosis factor or interleukin-1 initiates caspase activation, loss of mitochondrial membrane potential (Δψ), DNA degradation, and nuclear condensation and fragmentation characteristic of apoptotic cell death in human vascular endothelial cells (EC). Inhibition of phosphatidylinositol 3-kinase (PI3K) by LY294002, but not inhibition of Akt by dominant-negative mutation, also sensitizes EC to cytokine-initiated apoptosis. Cytokine-initiated caspase activation is slower and comparatively less with LY294002 than with cycloheximide. Cycloheximide but not LY294002 decreases expression of c-FLIP (cellular FLICE inhibitory protein), an inhibitor of caspase-8 activation. The caspase inhibitor zVADfmk completely blocks caspase activation, DNA degradation, and nuclear fragmentation in both cases but only prevents loss of Δψ and cell death for cytokine plus cycloheximide treatment. In contrast, overexpression of Bcl-2 protects EC treated with cytokine plus LY294002 but not EC treated with cytokine plus cycloheximide. The cathepsin B inhibitor CA-074-Me prevents loss of Δψ, caspase activation, and cell death for EC treated with cytokine plus LY294002 but has no effect on EC treated with cytokine plus cycloheximide. Cathepsin B translocates from lysosomes to cytosol following treatment with LY294002 prior to the activation of caspases. These results suggest that inhibition of PI3K allows cytokines to activate a cathepsin-dependent, mitochondrial death pathway in which caspase activation is secondary, is not inhibited by c-FLIP, and is not essential for cell death.
UR - http://www.scopus.com/inward/record.url?scp=0037742249&partnerID=8YFLogxK
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U2 - 10.1074/jbc.M212837200
DO - 10.1074/jbc.M212837200
M3 - Article
C2 - 12663669
AN - SCOPUS:0037742249
VL - 278
SP - 21295
EP - 21306
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 23
ER -