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Genetic ablation of the t-SNARE SNAP-25 distinguishes mechanisms of neuroexocytosis

Abstract

Axon outgrowth during development and neurotransmitter release depends on exocytotic mechanisms, although what protein machinery is common to or differentiates these processes remains unclear. Here we show that the neural t-SNARE (target-membrane-associated–soluble N-ethylmaleimide fusion protein attachment protein (SNAP) receptor) SNAP-25 is not required for nerve growth or stimulus-independent neurotransmitter release, but is essential for evoked synaptic transmission at neuromuscular junctions and central synapses. These results demonstrate that the development of neurotransmission requires the recruitment of a specialized SNARE core complex to meet the demands of regulated exocytosis.

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Figure 1: The Snap25 mutation abolishes expression of SNAP-25 protein.
Figure 2: Brain structure and synaptic protein levels appear normal in Snap25−/− mice.
Figure 3: Histopathological examination of SNAP-25-deficient fetuses.
Figure 4: The NMJ is formed in Snap25 mutants, but does not show ACh release.
Figure 5: Snap25−/− central neurons exhibit normal synaptic morphology both in culture and in vivo.
Figure 6: Spontaneous, AP-independent neurotransmission, constitutive exo-/endocytosis, but not evoked neuroexocytosis in Snap25−/− neurons.

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Acknowledgements

We thank J. Plomp for advice and help in embryonic neuromuscular electrophysiology, S. Nixon for technical assistance, E. Padilla at the UNM-HSC Animal Resource Facility for maintaining the mouse colony and G. Adamson at the UC Davis EM Pathology lab for help with electron microscopy. We also thank P. De Camilli and A. Klip for antisera, and B. Shuttleworth and L. Anna Cunningham for discussions and for reading the manuscript. The work was supported by NIH MH 4-8989 (M.C.W.).

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Correspondence to Michael C. Wilson.

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Washbourne, P., Thompson, P., Carta, M. et al. Genetic ablation of the t-SNARE SNAP-25 distinguishes mechanisms of neuroexocytosis. Nat Neurosci 5, 19–26 (2002). https://doi.org/10.1038/nn783

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