Incorporation of synaptotagmin II to the axolemma of botulinum type-A poisoned mouse motor endings during enhanced quantal acetylcholine release.
The involvement of terminal sprouts in neurotransmitter release by in vivo botulinum type-A toxin poisoned motor endings was investigated 15 to 40 days after a single injection of the toxin onto the levator auris longus muscle of the mouse. Enhanced quantal acetylcholine release was induced by alpha-latrotoxin or La3+ in conditions that prevent endocytosis, and an antibody directed against the lumenal domain of synaptotagmin II (Syt II) was used in the presence or absence of Triton X-100. We showed that, under resting conditions, the intravesicular domain of Syt II requires Triton X-100 to be labelled, whereas it becomes exposed to the outside of the axolemma of both the original terminal arborization and the newly formed sprouts during enhanced exocytosis. These data were taken to indicate that, when sprouting is prominent, the whole modified terminal arborization, including the original branches and the sprouts, possesses the machinery for Ca2+-independent exocytosis.
Laboratoire de Neurobiologie Cellulaire et Moléculaire, CNRS, 91198 Gif-sur-Yvette Cedex, France. angaut@cnrs-gif.fr
D
D
Angaut-Petit
J
J
Molgó
L
L
Faille
P
P
Juzans
M
M
Takahashi
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D019274:Botulinum Toxins, Type A / Q000506:poisoning*; D005089:Exocytosis / Q000502:physiology; D005260:Female; D007811:Lanthanum / Q000494:pharmacology; D051379:Mice; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism*; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D013111:Spider Venoms / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D050861:Synaptotagmin II
D009419:Nerve Tissue Proteins; D013111:Spider Venoms; D050861:Synaptotagmin II; C494263:Syt2 protein, mouse; C020763:alpha-latrotoxin; D007811:Lanthanum; D019274:Botulinum Toxins, Type A; D000109:Acetylcholine