Nuclear events of apoptosis in vitro in cell-free mitotic extracts: a model system for analysis of the active phase of apoptosis.

We have developed a cell-free system that induces the morphological transformations characteristic of apoptosis in isolated nuclei

Y A Lazebnik; S Cole; C A Cooke; W G Nelson; W C Earnshaw

2004

Scholarcy highlights

  • We have developed a cell-free system that induces the morphological transformations characteristic of apoptosis in isolated nuclei
  • We report here the surprising result that the changes undergone by nuclei in those extracts correspond not to mitotic chromosome condensation, but instead to the nuclear changes that occur during the active phase of apoptosis
  • A number of dramatic correspondences between the changes undergone by isolated nuclei in S/M extracts and by nuclei in cells during apoptosis in vivo lead us to conclude that the in vitro process described here is a useful model for the active phase of apoptosis
  • Zn2+has been shown to inhibit apoptosis in murine thymocytes and to inhibit cellular nucleases thought to be involved in apoptosis. The terminal phase of the process undergone by nuclei in S/M extracts is an active fragmentation by blebbing apart into membrane-enclosed vesicles. This resembles the final structural changes seen during apoptosis in cultured cells and is completely unlike any effect on nuclear structure described to date in cell-free systems derived from mitotic or meiotic cells. The changes in structural organization undergone by nuclei in S/M extracts are accompanied by the disassembly of the nuclear lamina. This observation from the cell free system has been shown to apply to intact cells as well, and we have demonstrated here that ceils from mouse, human and chicken all disassemble their nuclear lamina during apoptosis in vivo
  • Several similarities between apoptosis and mitosis led to the suggestion that these two processes are somehow related. These included the dramatic condensation of the chromatin during apoptosis, the timing required for the active phase of apoptosis, the observation that the final cellular fragmentation in apoptosis, like cytokinesis, is an actin-dependent process, and the observation that the nuclear lamina is disassembled during cell killing by cytotoxic T lymphocytes
  • As we have argued, S/M extracts provide an accurate model system for the final active phase of apoptosis, the characterization of apoptosis promoting activity is clearly of great interest, since this activity causes a unique morphological transformation that culminates in nuclear disintegration
  • (a) The nucleolus does not disassemble during the initial stages of apoptosis, either in vivo, or in isolated nuclei added to cell-free extracts with apoptosis promoting activity activity

Need more features? Save interactive summary cards to your Scholarcy Library.