Persistence of botulinum neurotoxin action in cultured spinal cord cells

FEBS Lett. 1999 Jul 30;456(1):137-42. doi: 10.1016/s0014-5793(99)00948-5.


Primary dissociated fetal mouse spinal cord cultures were used to study the mechanisms underlying the differences in persistence of botulinum neurotoxin A (BoNT/A) and botulinum neurotoxin/E (BoNT/E) activities. Spinal cord cultures were exposed to BoNT/A (0.4 pM) for 2-3 days, which converted approximately half of the SNAP-25 to an altered form lacking the final nine C-terminal residues. The distribution of toxin-damaged to control SNAP-25 remained relatively unchanged for up to 80 days thereafter. Application of a high concentration of BoNT/E (250 pM) either 25 or 60 days following initial intoxication with BoNT/A converted both normal and BoNT/A-truncated SNAP-25 into a single population lacking the final 26 C-terminal residues. Excess BoNT/E was removed by washout, and recovery of intact SNAP-25 was monitored by Western blot analysis. The BoNT/E-truncated species gradually diminished during the ensuing 18 days, accompanied by the reappearance of both normal and BoNT/A-truncated SNAP-25. Return of BoNT/A-truncated SNAP-25 was observed in spite of the absence of BoNT/A in the culture medium during all but the first 3 days of exposure. These results indicate that proteolytic activity associated with the BoNT/A light chain persists inside cells for > 11 weeks, while recovery from BoNT/E is complete in < 3 weeks. This longer duration of enzymatic activity appears to account for the persistence of serotype A action.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Botulinum Toxins / metabolism*
  • Botulinum Toxins / pharmacology
  • Botulinum Toxins, Type A / metabolism*
  • Botulinum Toxins, Type A / pharmacology
  • Cells, Cultured / metabolism
  • Female
  • Membrane Proteins*
  • Mice
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Nerve Tissue Proteins / metabolism
  • Peptide Hydrolases / metabolism
  • Spinal Cord / cytology
  • Spinal Cord / drug effects
  • Spinal Cord / embryology
  • Spinal Cord / metabolism*
  • Synaptosomal-Associated Protein 25


  • Membrane Proteins
  • Nerve Tissue Proteins
  • Snap25 protein, mouse
  • Synaptosomal-Associated Protein 25
  • Peptide Hydrolases
  • Botulinum Toxins
  • Botulinum Toxins, Type A
  • botulinum toxin type E