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Minimum essential factors required for vesicle mobilization at hippocampal synapses
Marina G Mozhayeva1, Maria F Matos, Xinran Liu
1Center for Basic Neuroscience, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9111, USA.
Summary
Guanosine triphosphate (GTP) and calcium ions (Ca2+) are crucial for vesicle mobilization and replenishment in hippocampal synapses. This process does not require ATP-dependent priming or soluble NSF-attachment protein receptor (SNARE) recycling.
Area of Science:
- Neuroscience
- Cell Biology
- Synaptic Transmission
Background:
- Studying presynaptic terminal mechanisms is challenging due to synapse inaccessibility to soluble reagents.
- Developing methods to manipulate the presynaptic terminal interior is essential for understanding synaptic function.
Purpose of the Study:
- To investigate the role of GTP and ATP in vesicle mobilization and replenishment at hippocampal synapses.
- To elucidate the mechanisms underlying the formation and recycling of soluble NSF-attachment protein receptor (SNARE) complexes.
Main Methods:
- Permeabilization of cultured hippocampal synapses to allow manipulation of the interior.
- Monitoring vesicle mobilization using the styryl dye FM2-10.
- Analyzing vesicle depletion via electron microscopy.
Main Results:
- GTP or GTP-gamma-S, along with 1 µM Ca2+, mobilized ~90% of the recycling pool.
- GDP-beta-S dialysis followed by 1 µM Ca2+ mobilized ~30% of vesicles, likely the readily releasable pool.
- Vesicle replenishment was GTP-dependent, did not require ATP or N-ethylmaleimide-sensitive factor (NSF), but involved new SNARE complex formation.
Conclusions:
- GTP and Ca2+ are essential for vesicle mobilization and replenishment of the readily releasable pool in hippocampal synapses.
- ATP-dependent priming and SNARE recycling are not required for this process.
- The findings highlight a novel GTP-dependent pathway for synaptic vesicle cycling.