Efficient stimulus-secretion coupling at ribbon synapses requires RIM-binding protein tethering of L-type Ca2+ channels.
Proc Natl Acad Sci U S A
; 114(38): E8081-E8090, 2017 09 19.
Article
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| MEDLINE
| ID: mdl-28874522
ABSTRACT
Fast neurotransmitter release from ribbon synapses via Ca2+-triggered exocytosis requires tight coupling of L-type Ca2+ channels to release-ready synaptic vesicles at the presynaptic active zone, which is localized at the base of the ribbon. Here, we used genetic, electrophysiological, and ultrastructural analyses to probe the architecture of ribbon synapses by perturbing the function of RIM-binding proteins (RBPs) as central active-zone scaffolding molecules. We found that genetic deletion of RBP1 and RBP2 did not impair synapse ultrastructure of ribbon-type synapses formed between rod bipolar cells (RBCs) and amacrine type-2 (AII) cells in the mouse retina but dramatically reduced the density of presynaptic Ca2+ channels, decreased and desynchronized evoked neurotransmitter release, and rendered evoked and spontaneous neurotransmitter release sensitive to the slow Ca2+ buffer EGTA. These findings suggest that RBPs tether L-type Ca2+ channels to the active zones of ribbon synapses, thereby synchronizing vesicle exocytosis and promoting high-fidelity information transfer in retinal circuits.
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Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Sinapsis
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Células Fotorreceptoras Retinianas Bastones
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Canales de Calcio Tipo L
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Células Amacrinas
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Células Bipolares de la Retina
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Proteínas Celulares de Unión al Retinol
Límite:
Animals
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2017
Tipo del documento:
Article