title: Events in apoptosis. Acidification is downstream of protease activation and BCL-2 protection.
abstract: Cytoplasmic acidification is now recognized as a feature of apoptosis in a variety of systems. However, its relation to other events in the process of apoptosis is not yet characterized. In this work, we examined the effect of BCL-2 overexpression on acidification mediated by cycloheximide treatment or Fas ligation in Jurkat T-lymphoblasts. We find that BCL-2 overexpression attenuates cytoplasmic acidification and apoptosis detected by annexin V labeling. Acidification and phosphatidylserine externalization were found to occur concurrently. We also examined the requirement for protease activation for cytoplasmic acidification to occur and found that inhibition of interleukin-1beta converting enzyme/CED-3 family proteases (using carbobenzoxy-Val-Ala-Asp-fluoromethylketone, an inhibitor of these proteases) prevents acidification and apoptosis mediated by Fas ligation. These studies suggest that BCL-2 acts at a point upstream of acidification and that protease activation is also upstream of acidification.
authors.affiliation: Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: G W
authors.initials: GW
authors.lastname: Meisenholder
authors.forename: S J
authors.initials: SJ
authors.lastname: Martin
authors.forename: D R
authors.initials: DR
authors.lastname: Green
authors.forename: J
authors.initials: J
authors.lastname: Nordberg
authors.forename: B M
authors.initials: BM
authors.lastname: Babior
authors.forename: R A
authors.initials: RA
authors.lastname: Gottlieb
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis; D001578:Benzopyrans; D029742:Caenorhabditis elegans Proteins; D020170:Caspase 1; D020169:Caspases; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004789:Enzyme Activation; D005456:Fluorescent Dyes; D015801:Helminth Proteins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009284:Naphthols / Q000494:pharmacology; D009842:Oligopeptides / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins / Q000378:metabolism; D012235:Rhodamines / Q000494:pharmacology; D014162:Transfection
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D001578:Benzopyrans; D029742:Caenorhabditis elegans Proteins; D015853:Cysteine Proteinase Inhibitors; D005456:Fluorescent Dyes; D015801:Helminth Proteins; D009284:Naphthols; D009842:Oligopeptides; D011480:Protease Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D012235:Rhodamines; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C091666:seminaphthorhodaminefluoride; D011505:Protein-Tyrosine Kinases; D020169:Caspases; D003546:Cysteine Endopeptidases; C089223:ced-3 protein, C elegans; D020170:Caspase 1