Cleavage of Rabaptin-5 blocks endosome fusion during apoptosis

Sabina C. Cosulich, Hisanori Horiuchi, Marino Zerial, Paul R. Clarke, Philip G. Woodman (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

70 Citations (Scopus)


Cells undergoing apoptosis exhibit striking changes in membrane organization, including plasma membrane blebbing and invagination, vacuolation and fragmentation of organelles, and alterations in the surface expression of receptors. The underlying mechanisms for these changes are unknown, though alterations in vesicular fusion are likely to play a role. Using a cell-free system based on Xenopus laevis egg extracts we have found that endosome fusion is blocked during apoptosis. Inhibition of fusion is prevented by Bcl-2 or Bcl-x(L), two negative regulators of apoptosis, or by specific inhibitors of members of the caspase family of apoptotic proteases. Selective cleavage of Rabaptin-5, an essential and rate-limiting component of endosome fusion, is responsible for the loss of fusion activity. Cleavage of Rabaptin-5 also occurs in cellular models for apoptosis. These results suggest that inactivation of Rabaptin-5 and inhibition of vesicle transport lead to fragmentation of endosomes and inhibition of the endocytic pathway during the execution phase of apoptosis. We propose that parallel changes to other membrane transport pathways would give rise to general membrane fragmentation in apoptotic cells. These changes are likely to play an important role in the generation of apoptotic bodies and their recognition by phagocytosing cells.

Original languageEnglish
Pages (from-to)6182-6191
Number of pages10
JournalEMBO Journal
Issue number20
Early online date15 Oct 1997
Publication statusPublished - 5 Nov 1997


  • Apoptosis
  • Bcl-2
  • Caspase
  • Fusion
  • Rabaptin-5

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • General Immunology and Microbiology
  • General Biochemistry,Genetics and Molecular Biology


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