Bcl-2 antibodies induce hemoglobin release by red blood cells loaded with in vitro translated Bcl-2 and its cleaved fragment

Apoptosis induced by proteasome inhibitor in human THP-1 leukemia cells is associated with the cleavage of Bcl-2 into a shortened fragment, Bcl-2/Delta34. Both Bcl-2 and its cleaved fragment were located exclusively on the mitochondria of THP-1 cells. No translocation of Bcl-2 or Bcl-2/Delta34 to th...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2000-04, Vol.270 (3), p.816-820
Main Authors: Chen, C, Lin, H, Chen, B D
Format: Article
Language:English
Subjects:
Animals
Antibodies - pharmacology
Apoptosis
Caspase 3
Caspases - metabolism
Cytosol - metabolism
Enzyme Activation
Erythrocytes - physiology
Hemoglobins - metabolism
Humans
Leukemia
Mitochondria - metabolism
Protein Biosynthesis
Proto-Oncogene Proteins c-bcl-2 - genetics
Proto-Oncogene Proteins c-bcl-2 - immunology
Proto-Oncogene Proteins c-bcl-2 - metabolism
Sheep
Transcription, Genetic
Tumor Cells, Cultured
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Summary:Apoptosis induced by proteasome inhibitor in human THP-1 leukemia cells is associated with the cleavage of Bcl-2 into a shortened fragment, Bcl-2/Delta34. Both Bcl-2 and its cleaved fragment were located exclusively on the mitochondria of THP-1 cells. No translocation of Bcl-2 or Bcl-2/Delta34 to the cytosolic fraction was detected during apoptosis. Treatment of isolated mitochondria with recombinant caspase-3 induced the same cleavage of Bcl-2 in vitro and triggered the release of cytochrome c from the mitochondria. The ability of Bcl-2/Delta34 in regulating the opening of membrane "pores" was investigated using a sheep red blood cell (RBC) model with in vitro translated Bcl-2/Delta34 and Bcl-2 proteins. Bcl-2 and Bcl-2/Delta34 generated in vitro were relocated rapidly to sheep RBC but caused no hemoglobin release in either case. Addition of anti-Bcl-2 antibodies directly to the RBC that had been loaded with either Bcl-2 or Bcl-2/Delta34 resulted in a rapid release of hemoglobin from the blood cells. Treatment of the sheep RBC with anti-Bcl-2 or anti-sheep RBC antibodies alone did not trigger hemoglobin release from the RBC. Based on these findings, we proposed that, upon "enforced aggregation," both Bcl-2 and Bcl-2/Delta34 can form "pores" in membranes, which may contribute to the release of cytochrome c in apoptosis.
ISSN:0006-291X
DOI:10.1006/bbrc.2000.2520