Extent and limitation of the control of nuclear apoptosis by DNA-fragmenting factor

Biochem Biophys Res Commun. 1999 Jan 27;254(3):552-8. doi: 10.1006/bbrc.1998.9982.


During apoptosis, changes to the nucleus of the dying cell include DNA degradation and structural collapse. These changes are accomplished by caspase-mediated cleavage of DNA-fragmenting factor DFF45, an inhibitor of the effector molecule DFF40. DFF45 and, more efficiently, a mutant lacking one caspase-cleavage site (DFF45m) inhibited nuclear changes in a cell-free system when apoptosis was initiated by adding caspase-3 to cell extracts. In primary tissues from several mammalian species, human caspase-3 activated and human DFF45m blocked nuclear apoptosis demonstrating evolutionary conservation of this step. However, DFF45m did not significantly inhibit DNA-fragmenting activity in extracts from staurosporine-treated cells from the human cell line Jurkat. In extracts from normal Jurkat cells, DFF45m blocked caspase-triggered DNA cleavage efficiently only if added within a short time of the addition of the caspase. At later time points, this inhibition by DFF45m was strongly reduced in efficiency while Zn2+ still completely blocked DNA fragmentation. These results demonstrate the evolutionary conservation of a linear pathway in apoptosis and suggest the existence of more complex events as final effector machinery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Caspase 3
  • Caspases / metabolism
  • Cell Nucleus / metabolism*
  • DNA / metabolism
  • Enzyme Activation
  • Humans
  • Hydrolysis
  • Proteins / metabolism*
  • Tumor Cells, Cultured


  • Proteins
  • caspase-activated DNase inhibitor
  • DNA
  • CASP3 protein, human
  • Caspase 3
  • Caspases