Sustaining rapid vesicular release at active zones: potential roles for vesicle tethering

• Published in: Trends in neurosciences (Regular ed.) Vol. 36; no. 3; pp. 185 - 194
• Main Authors: Hallermann, Stefan, Silver, R. Angus
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2013; Elsevier Sequoia S.A
• Subjects: Action Potentials; active zone; Animals; Brain; Caenorhabditis elegans Proteins - physiology; Cell Communication - physiology; Cell Membrane - ultrastructure; Cytoskeletal Proteins - physiology; Drosophila Proteins - physiology; high-frequency signaling; Humans; Information processing; Kinetics; Membrane Fusion; Microscopy, Electron; Nerve Tissue Proteins - physiology; Nervous system; Neurology; Neuromuscular Junction - physiology; Neuromuscular Junction - ultrastructure; Neurons - metabolism; Neurons - ultrastructure; Neurosciences; Neurotransmitter Agents - metabolism; Proteins; SNARE Proteins - physiology; Species Specificity; synapse; Synaptic Transmission - physiology; Synaptic Vesicles - physiology; Synaptic Vesicles - ultrastructure; vesicle tethering; vesicle tethering; synapse; high-frequency signaling; active zone
• ISSN: 0166-2236; 1878-108X
• DOI: 10.1016/j.tins.2012.10.001

Rapid information processing in our nervous system relies on high-frequency fusion of transmitter-filled vesicles at chemical synapses. Some sensory synapses possess prominent electron-dense ribbon structures that provide a scaffold for tethering synaptic vesicles at the active zone (AZ), enabling sustained vesicular release. Here, we review functional data indicating that some central and neuromuscular synapses can also sustain vesicle-fusion rates that are comparable to those of ribbon-type sensory synapses. Comparison of the ultrastructure across these different types of synapses, together with recent work showing that cytomatrix proteins can tether vesicles and speed vesicle reloading, suggests that filamentous structures may play a key role in vesicle supply. We discuss potential mechanisms by which vesicle tethering could contribute to sustained high rates of vesicle fusion across ribbon-type, central, and neuromuscular synapses.