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Oligonucleosome DNA fragmentation of caspase 3 deficient MCF-7 cells in palmitate-induced apoptosis

D V Semenov1, P A Aronov, E V Kuligina

  • 1Novosibirsk Institute of Bioorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia. semenov@niboch.nsc.ru

Nucleosides, Nucleotides & Nucleic Acids
|November 25, 2004
PubMed

Insights

Palmitate induces DNA fragmentation in caspase-3 deficient cells, bypassing the usual apoptotic pathway. This suggests a caspase-7 dependent mechanism involving DFF40-like nucleases in apoptosis.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Oligonucleosomal DNA fragmentation is a key feature of apoptosis.
  • This process is typically mediated by DFF40/CAD DNase, activated by caspase-3.
  • Caspase-3 deficient cells usually do not exhibit DNA fragmentation.

Purpose of the Study:

  • To investigate the mechanism of palmitate-induced apoptosis in caspase-3 deficient MCF-7 cells.
  • To identify the nucleases involved in DNA fragmentation in this context.
  • To explore the role of caspases in palmitate-induced DNA fragmentation.

Main Methods:

  • SDS-DNA-PAGE assay to detect DNase activation.
  • Cell-free system using microsomes and human placental chromatin to assess nuclease activity.
  • Inhibition studies using caspase-3/7 inhibitor Ac-DEVD-CHO.

Main Results:

  • Palmitate induced nuclear apoptosis and DNA fragmentation in caspase-3 deficient MCF-7 cells.
  • 40-50 kDa DFF40-like DNases were activated and accumulated in nuclei and cytoplasm.
  • Microsomes from apoptotic cells fragmented chromatin in a cell-free system.
  • DNase activation and chromatin fragmentation were inhibited by Ac-DEVD-CHO.

Conclusions:

  • Palmitate can trigger oligonucleosomal DNA fragmentation independently of caspase-3.
  • Microsome-associated caspase-7 appears to be crucial for this process in caspase-3 deficient cells.
  • This suggests an alternative pathway for DNA fragmentation during apoptosis.

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