Expression of BAX in cell nucleus after experimentally induced apoptosis revealed by immunogold and embedment-free electron microscopy

Cell Biol Int. 2001;25(8):725-33. doi: 10.1006/cbir.2001.0768.


The unique combination of immunocytochemistry with embedment-free electron microscopy was applied for precise and specific localisation of BAX in the human colon adenocarcinoma COLO 205 cell line stimulated to undergo apoptosis by camptothecin (DNA topoisomerase I inhibitor). Camptothecin-induced apoptosis was associated with redistribution of BAX from cytosol to organelle membranes: mitochondria, Golgi apparatus, endoplasmic reticulum and via nuclear envelope pores to the nucleus, occurring within 60-180 min of cell exposure to the drug. An increase in BAX immunoreactivity on fine filaments and the lamina-pore complex of the nuclear matrix was also observed. The increase in BAX expression in the nuclear area of camptothecin-treated COLO 205 cells was confirmed by quantitative analysis using laser scanning cytometry. The subcellular translocations of BAX preceded the appearance of any morphological symptoms of apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis* / drug effects
  • Camptothecin / pharmacology
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism*
  • Cell Nucleus / ultrastructure
  • Cytoplasm / metabolism
  • Cytoplasm / ultrastructure
  • Endoplasmic Reticulum / metabolism
  • Endoplasmic Reticulum / ultrastructure
  • Flow Cytometry / methods
  • Golgi Apparatus / metabolism
  • Golgi Apparatus / ultrastructure
  • Humans
  • Intracellular Membranes / metabolism
  • Intracellular Membranes / ultrastructure
  • Microscopy, Electron / methods
  • Microscopy, Immunoelectron
  • Mitochondria / metabolism
  • Mitochondria / ultrastructure
  • Nuclear Envelope / metabolism
  • Nuclear Envelope / ultrastructure
  • Proto-Oncogene Proteins / biosynthesis*
  • Proto-Oncogene Proteins c-bcl-2*
  • Topoisomerase I Inhibitors
  • Tumor Cells, Cultured
  • bcl-2-Associated X Protein


  • BAX protein, human
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Topoisomerase I Inhibitors
  • bcl-2-Associated X Protein
  • Camptothecin