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Inhibition of Bid-induced Apoptosis by Bcl-2
- Source :
- Journal of Biological Chemistry. 278:16992-16999
- Publication Year :
- 2003
- Publisher :
- Elsevier BV, 2003.
-
Abstract
- Bcl-2 family proteins are important regulators of apoptosis. They can be pro-apoptotic (e.g. Bid, Bax, and Bak) or anti-apoptotic (e.g. Bcl-2 and Bcl-xL). The current study examined Bid-induced apoptosis and its inhibition by Bcl-2. Transfection of Bid led to apoptosis in HeLa cells. In these cells, Bid was processed into active forms of truncated Bid or tBid. Following processing, tBid translocated to the membrane-bound organellar fraction. Bcl-2 co-transfection inhibited Bid-induced apoptosis but did not prevent Bid processing or tBid translocation. On the other hand, Bcl-2 blocked the release of mitochondrial cytochromec in Bid-transfected cells, suggesting actions at the mitochondrial level. Alkaline treatment stripped off tBid from the membrane-bound organellar fraction of Bid plus Bcl-2-co-transfected cells, but not from cells transfected with only Bid, suggesting inhibition of tBid insertion into mitochondrial membranes by Bcl-2. Bcl-2 also prevented Bid-induced Bax translocation from cytosol to the membrane-bound organellar fraction. Finally, Bcl-2 diminished Bid-induced oligomerization of Bax and Bak within the membrane-bound organellar fraction, shown by cross-linking experiments. In conclusion, Bcl-2 inhibited Bid-induced apoptosis at the mitochondrial level by blocking cytochrome c release, without suppressing Bid processing or activation. Critical steps blocked by Bcl-2 included tBid insertion, Bax translocation, and Bax/Bak oligomerization in the mitochondrial membranes.
- Subjects :
- Truncated BID
Cytochrome c
Chromosomal translocation
Cell Biology
Transfection
Mitochondrion
Biology
urologic and male genital diseases
biology.organism_classification
Biochemistry
Molecular biology
digestive system diseases
Cell biology
HeLa
Cytosol
Apoptosis
biology.protein
heterocyclic compounds
biological phenomena, cell phenomena, and immunity
neoplasms
Molecular Biology
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 278
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi...........90ada55d36d8980dab276be437f081ad