Cell-cycle-dependent resistance to Bacillus thuringiensis Cry1C toxin in Sf9 cells

Dror Avisar, Michal Segal, Baruch Sneh, Aviah Zilberstein*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The Sf9 cell line, derived from the moth Spodoptera frugiperda, is highly and specifically sensitive to the Bacillus thuringiensis Cry1C toxin. Upon exposure to Cry1C, ionic pores are formed in the plasma membrane leading to cell swelling and death. Here, we describe a unique transient tolerance to Cry1C of dividing cells, which allowed completion of the division process in the presence of Cry1C. Correlatively, arresting the cells at G2-M phase by nocodazole treatment rendered them insensitive to Cry1C. When the arresting agent was removed, the cells completed their division and gradually regained Cry1C sensitivity. In comparison to normal cells with 1-2% cell-division frequency, the M-phase arrested cells bound less toxin in binding assays. Moreover, no lipid rafts could be isolated from the membranes of M-phase arrested cells. Caveolin-1, identified here for the first time in insect cells, was immunodetected as a lipid raft component of normal cells, but was only present in the membrane-soluble fraction of G2-M-arrested cells. Thus M-phase-linked changes in lipid raft organization may account for diminished Cry1C binding and toxicity. Furthermore, considering the pivotal role of lipid rafts in different cell functions of many cell types, the lack of organized lipid rafts in dividing cells may transiently affect cell susceptibility to pathogens, toxins and other lipid raft-linked functions.

Original languageEnglish
Pages (from-to)3163-3171
Number of pages9
JournalJournal of Cell Science
Issue number14
StatePublished - 15 Jul 2005


  • Bacillus thuringiensis
  • Caveolin
  • Cell cycle
  • Cry1C
  • Lipid rafts
  • Resistance


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