Bcl-2, Bcl-XL and adenovirus protein E1B19kD are functionally equivalent in their ability to inhibit cell death.
Apoptosis is the physiological process by which unwanted cells in an organism are killed. Bcl-2, a membrane-bound cytoplasmic protein, is an effective inhibitor of apoptotic cell death induced by many cytotoxic agents. Survival-promoting homologues of Bcl-2 include its close relative, Bcl-xL and the 19 kD protein encoded by the E1B gene of adenoviruses. Whether these proteins are functionally equivalent and whether they can antagonise all or only some pathways to apoptosis is unresolved. We have carried out a systematic comparison of Bcl-2, Bcl-xL and adenovirus E1B19kD activity, using several cell lines and a range of cytotoxic conditions. High levels of expression of each of these proteins inhibited apoptosis induced by growth factor deprivation or treatment with gamma-radiation, glucocorticoid and various cytotoxic drugs. In contrast, none of them could effectively counter apoptosis induced via the TNF receptor or Fas/APO-1 (CD95). Biochemical analysis revealed that all three proteins can associate with Bax and Bak, members of the Bcl-2 protein subfamily that can facilitate apoptosis. The results provide evidence that Bcl-2, Bcl-xL and adenovirus protein E1B19kD are indistinguishable in their ability to regulate the cell death effector machinery.
Huang
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DC
The Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.
Cory
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Strasser
A
A
D017501:Adenovirus E1B Proteins / Q000096:biosynthesis*; D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival; D003513:Cycloheximide / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D005720:Gamma Rays; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D019169:Jurkat Cells; D007700:Kinetics; D051379:Mice; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000494:pharmacology; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D051020:bcl-X Protein
D017501:Adenovirus E1B Proteins; D000970:Antineoplastic Agents; C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D007377:Interleukin-3; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D051020:bcl-X Protein; D003907:Dexamethasone; D016572:Cyclosporine; D003513:Cycloheximide; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate