title: Antagonism of botulinum toxin type A-induced cleavage of SNAP-25 in rat cerebral synaptosome by toosendanin.
abstract: Toosendanin (TSN), a triterpenoid derivative extracted from Chinese traditional medicine, has been demonstrated to be an effective cure for experimental botulism. This study is designed to explore its antibotulismic mechanism by Western blotting. The results showed that TSN incubation did not change the electrophoresis pattern and the amounts of synaptosomal-associated protein of 25 kDa (SNAP-25), syntaxin and synaptobrevin/vesicle-associated membrane protein in rat cerebral synaptosomes, but made the synaptosomes completely resistant to botulinum neurotoxin A (BoNT/A)-mediated cleavage of SNAP-25. After binding of BoNT/A to synaptosomes, TSN still partially antagonized the toxin-mediated cleavage of SNAP-25. However, TSN-incubated synaptosomal membrane fraction did not resist the cleavage of SNAP-25 by the light chain of BoNT/A. It is suggested that the antibotulismic effect of TSN results from blocking the toxin's approach to its enzymatic substrate.
authors.affiliation: Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, PR China.
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Zhou
authors.forename: Zhong-Feng
authors.initials: ZF
authors.lastname: Wang
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Ren
authors.forename: Mian-Zhi
authors.initials: MZ
authors.lastname: Tang
authors.forename: Yu-Liang
authors.initials: YL
authors.lastname: Shi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019274:Botulinum Toxins, Type A / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D008297:Male; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010084:Oxidation-Reduction; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D050600:SNARE Proteins; D050825:Synaptosomal-Associated Protein 25; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D033921:Vesicular Transport Proteins; D014315:Triterpenes
chemical_list: D019274:Botulinum Toxins, Type A; D004229:Dithiothreitol; D004365:Drugs, Chinese Herbal; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D050600:SNARE Proteins; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins; C494209:Snap25 protein, mouse; C494210:Snap25 protein, rat; C036454:toosendanin; D014315:Triterpenes