A dynamin 1-, dynamin 3- and clathrin-independent pathway of synaptic vesicle recycling mediated by bulk endocytosis
- Yale University School of Medicine, United States
- University of Colorado, United States
- Montreal Neurological Institute, McGill University, Canada
- Boston University School of Medicine, Canada
Abstract
The exocytosis of synaptic vesicles (SVs) elicited by potent stimulation is rapidly compensated by bulk endocytosis of SV membranes leading to large endocytic vacuoles ('bulk' endosomes). Subsequently, these vacuoles disappear in parallel with the reappearance of new SVs. We have used synapses of dynamin 1 and 3 double knock-out neurons, where clathrin-mediated endocytosis is dramatically impaired, to gain insight into the poorly understood mechanisms underlying this process. Massive formation of bulk endosomes was not defective, but rather enhanced, in the absence of dynamin 1 and 3. The subsequent conversion of bulk endosomes into SVs was not accompanied by the accumulation of clathrin coated buds on their surface and this process proceeded even after further clathrin knock-down, suggesting its independence of clathrin. These findings support the existence of a pathway for SV reformation that bypasses the requirement for clathrin and dynamin 1/3 and demonstrates the plasticity of the SV recycling process.
Article and author information
Author details
Reviewing Editor
- Reinhard Jahn, Max Planck Institute for Biophysical Chemistry, Germany
Ethics
Animal experimentation: the present study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All of the animals were handled according to approved institutional animal care and use committee (IACUC) protocols (#07422-2012) of Yale university. All animals were euthanized with CO2 and embryos were used for primary neuron culture.
Version history
- Received: October 1, 2013
- Accepted: June 24, 2014
- Accepted Manuscript published: June 24, 2014 (version 1)
- Accepted Manuscript updated: June 30, 2014 (version 2)
- Version of Record published: July 29, 2014 (version 3)
Copyright
© 2014, Wu et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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A dynamin 1-, dynamin 3- and clathrin-independent pathway of synaptic vesicle recycling mediated by bulk endocytosis
eLife 3:e01621.
https://doi.org/10.7554/eLife.01621
Further reading
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The cytosolic proteins synucleins and synapsins are thought to play cooperative roles in regulating synaptic vesicle (SV) recycling, but mechanistic insight is lacking. Here, we identify the synapsin E-domain as an essential functional binding-partner of α-synuclein (α-syn). Synapsin E-domain allows α-syn functionality, binds to α-syn, and is necessary and sufficient for enabling effects of α-syn at synapses of cultured mouse hippocampal neurons. Together with previous studies implicating the E-domain in clustering SVs, our experiments advocate a cooperative role for these two proteins in maintaining physiologic SV clusters.
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