Endonuclease activation during apoptosis: The role of cytosolic Ca2+ and pH

Michael A. Barry, Alan Eastman

Research output: Contribution to journalArticlepeer-review

181 Scopus citations


An axiom of apoptosis is that increases in cytosolic Ca2+ activate a Ca2+ Mg2+-dependent endonuclease. However, when HL-60 human promyelocytic leukemia cells were incubated with the Ca2+ ionophore ionomycin in varied extracellular Ca2+, DNA digestion was independent of extracellular Ca2+. Under these conditions, intracellular Ca2+ concentrations did not correlate with the observed DNA digestion. In contrast, intracellular acidification correlated well with DNA digestion. These data indicate that increased intracellular Ca2+ is not the primary signal for endonuclease activation in all forms of apoptosis, but that intracellular acidification may be involved. The observed intracellular acidification is consistent with the involvement of deoxyribonuclease II in apoptosis.

Original languageEnglish (US)
Pages (from-to)782-789
Number of pages8
JournalBiochemical and Biophysical Research Communications
Issue number2
StatePublished - Jul 31 1992

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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