Brefeldin A-mediated apoptosis requires the activation of caspases and is inhibited by Bcl-2.
Brefeldin A (BFA) has recently been shown to induce apoptosis in human tumor cells in a p53-independent fashion. In this study, BFA-induced apoptosis was analyzed in the human Jurkat T-cell line. Apoptosis occurred 8 h after treatment with BFA and at concentrations as low as 10 ng/ml and increased with the duration of BFA exposure. Forskolin, an inhibitor of BFA-induced deaggregation of the Golgi-microtubular complex in some cell lines, failed to reverse BFA-mediated apoptosis. Further study of the mechanism of BFA-induced apoptosis was conducted by using a series of peptide protease inhibitors. Complete inhibition of cell death was achieved with benzyloxycarbonyl-Val-Ala-Asp-fluromethylketone, a peptide inhibitor of the caspase protease family, and Z-Asp-Glu-Val-Asp-FMK, a specific inhibitor of caspase-3. Both Acetyl-Tyr-Val-Ala-Asp-chloromethylketone and Acetyl-Tyr-Val-Ala-Asp-aldehyde, selective caspase-1 (interleukin-1beta converting enzyme) inhibitors, exerted only partial protection of cells from apoptosis at higher concentrations. Z-Phe-Ala-FMK, a cysteine protease inhibitor lacking aspartate at the P1 position, did not have any impact on BFA-induced apoptosis. Furthermore, Jurkat cells transfected with the proto-oncoprotein Bcl-2, which is able to block various apoptotic conditions, showed remarkable resistance to the apoptotic effect of BFA. Thus, the data indicate that BFA-induced apoptosis requires caspase(s) activation, primarily the activation of caspase-3, and is inhibited by overexpression of Bcl-2.
Guo
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Department of Internal Medicine, Oregon Health Sciences University, Portland, Oregon, 97201, USA.
Tittle
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TV
Allen
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Maziarz
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RT
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis; D020126:Brefeldin A / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D019169:Jurkat Cells; D009842:Oligopeptides / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D014407:Tumor Cells, Cultured
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D009842:Oligopeptides; D019253:Proto-Oncogene Proteins c-bcl-2; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C096429:L 709049; D005576:Colforsin; D020126:Brefeldin A; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases