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Heat Shock Protein 70 Inhibits Apoptosis Downstream of Cytochrome c Release and Upstream of Caspase-3 Activation
- Source :
- Journal of Biological Chemistry. 275:25665-25671
- Publication Year :
- 2000
- Publisher :
- Elsevier BV, 2000.
-
Abstract
- Heat shock protein 70 (HSP70) has been shown to act as an inhibitor of apoptosis. We have also observed an inhibitory effect of HSP70 on apoptotic cell death both in preheated U937 and stably transfected HSP70-overexpressing U937 (U937/HSP70) cells. However, the molecular mechanism whereby HSP70 prevents apoptosis still remains to be solved. To address this issue, we investigated the effect of HSP70 on apoptotic processes in an in vitro system. Caspase-3 cleavage and DNA fragmentation were detected in cytosolic fractions from normal cells upon addition of dATP, but not from preheated U937 or U937/hsp70 cells. Moreover, the addition of purified recombinant HSP70 to normal cytosolic fractions prevented caspase-3 cleavage and DNA fragmentation, suggesting that HSP70 prevents apoptosis upstream of caspase-3 processing. Because cytochrome c was still released from mitochondria into the cytosol by lethal heat shock despite prevention of caspase-3 activation and cell death in both preheated U937 and U937/hsp70 cells, it was evident that HSP70 acts downstream of cytochrome c release. Results obtained in vitro with purified deletion mutants of HSP70 showed that the carboxyl one-third region (from amino acids 438 to 641) including the peptide-binding domain and the carboxyl-terminal EEVD sequence was essential to prevent caspase-3 processing. From these results, we conclude that HSP70 acts as a strong suppressor of apoptosis acting downstream of cytochrome c release and upstream of caspase-3 activation.
- Subjects :
- Programmed cell death
Hot Temperature
Cell Survival
Apoptosis
Cytochrome c Group
Caspase 3
DNA Fragmentation
Biology
Transfection
Inhibitor of apoptosis
Biochemistry
Mice
Cytosol
Animals
Humans
HSP70 Heat-Shock Proteins
Molecular Biology
Cell Nucleus
Cytochrome c
U937 Cells
Cell Biology
Flow Cytometry
Molecular biology
Recombinant Proteins
Protein Structure, Tertiary
Hsp70
Enzyme Activation
Liver
Caspases
Mutagenesis, Site-Directed
biology.protein
DNA fragmentation
Electrophoresis, Polyacrylamide Gel
Apoptosome
Gene Deletion
Protein Binding
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 275
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....980d0e92f6110b5a151454478ff6f368