Events in apoptosis. Acidification is downstream of protease activation and BCL-2 protection

J Biol Chem. 1996 Jul 5;271(27):16260-2. doi: 10.1074/jbc.271.27.16260.

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Chloromethyl Ketones / pharmacology
  • Apoptosis*
  • Benzopyrans
  • Caenorhabditis elegans Proteins
  • Caspase 1
  • Caspases*
  • Cell Line
  • Cysteine Endopeptidases / metabolism*
  • Cysteine Proteinase Inhibitors / pharmacology
  • Cytoplasm / metabolism
  • Enzyme Activation
  • Fluorescent Dyes
  • Helminth Proteins / metabolism*
  • Humans
  • Hydrogen-Ion Concentration
  • Naphthols / pharmacology
  • Oligopeptides / metabolism
  • Protease Inhibitors / pharmacology
  • Protein-Tyrosine Kinases / biosynthesis
  • Proto-Oncogene Proteins / biosynthesis*
  • Proto-Oncogene Proteins c-bcl-2
  • Recombinant Proteins / metabolism
  • Rhodamines / pharmacology
  • Transfection

Substances

  • Amino Acid Chloromethyl Ketones
  • Benzopyrans
  • Caenorhabditis elegans Proteins
  • Cysteine Proteinase Inhibitors
  • Fluorescent Dyes
  • Helminth Proteins
  • Naphthols
  • Oligopeptides
  • Protease Inhibitors
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Recombinant Proteins
  • Rhodamines
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • seminaphthorhodaminefluoride
  • Protein-Tyrosine Kinases
  • Caspases
  • Cysteine Endopeptidases
  • ced-3 protein, C elegans
  • Caspase 1