Endophilin A and B Join Forces With Clathrin to Mediate Synaptic Vesicle Recycling in Caenorhabditis elegans

Synaptic vesicles must be recycled to sustain neurotransmission, in large part via clathrin-mediated endocytosis. Clathrin is recruited to endocytic sites on the plasma membrane by the AP2 adaptor complex. The medium subunit (μ2) of AP2 binds to cargo proteins and phosphatidylinositol-4,5-bisphosphate on the cell surface. Here, we characterize the apm-2 gene (also called dpy-23), which encodes the only μ2 subunit in the nematode Caenorhabditis elegans. APM-2 is highly expressed in the nervous system and is localized to synapses; yet specific loss of APM-2 in neurons does not affect locomotion. In apm-2 mutants, clathrin is mislocalized at synapses, and synaptic vesicle numbers and evoked responses are reduced to 60 and 65%, respectively. Collectively, these data suggest AP2 μ2 facilitates but is not essential for synaptic vesicle recycling.

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High-Throughput All-Optical Analysis of Synaptic Transmission and Synaptic Vesicle Recycling in Caenorhabditis elegans

PLoS ONE ◽

10.1371/journal.pone.0135584 ◽

2015 ◽

Vol 10 (8) ◽

pp. e0135584 ◽

Cited By ~ 9

Author(s):

Sebastian Wabnig ◽

Jana Fiona Liewald ◽

Szi-chieh Yu ◽

Alexander Gottschalk

Keyword(s):

Caenorhabditis Elegans ◽

Synaptic Transmission ◽

Synaptic Vesicle ◽

High Throughput ◽

Optical Analysis ◽

Synaptic Vesicle Recycling ◽

Vesicle Recycling ◽

All Optical

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Mutations in Synaptojanin Disrupt Synaptic Vesicle Recycling

The Journal of Cell Biology ◽

10.1083/jcb.150.3.589 ◽

2000 ◽

Vol 150 (3) ◽

pp. 589-600 ◽

Cited By ~ 179

Author(s):

Todd W. Harris ◽

Erika Hartwieg ◽

H. Robert Horvitz ◽

Erik M. Jorgensen

Keyword(s):

Plasma Membrane ◽

Caenorhabditis Elegans ◽

Synaptic Vesicle ◽

Synaptic Vesicles ◽

Vesicle Trafficking ◽

Synaptic Vesicle Recycling ◽

Vesicle Recycling ◽

Synaptojanin 1

Synaptojanin is a polyphosphoinositide phosphatase that is found at synapses and binds to proteins implicated in endocytosis. For these reasons, it has been proposed that synaptojanin is involved in the recycling of synaptic vesicles. Here, we demonstrate that the unc-26 gene encodes the Caenorhabditis elegans ortholog of synaptojanin. unc-26 mutants exhibit defects in vesicle trafficking in several tissues, but most defects are found at synaptic termini. Specifically, we observed defects in the budding of synaptic vesicles from the plasma membrane, in the uncoating of vesicles after fission, in the recovery of vesicles from endosomes, and in the tethering of vesicles to the cytoskeleton. Thus, these results confirm studies of the mouse synaptojanin 1 mutants, which exhibit defects in the uncoating of synaptic vesicles (Cremona, O., G. Di Paolo, M.R. Wenk, A. Luthi, W.T. Kim, K. Takei, L. Daniell, Y. Nemoto, S.B. Shears, R.A. Flavell, D.A. McCormick, and P. De Camilli. 1999. Cell. 99:179–188), and further demonstrate that synaptojanin facilitates multiple steps of synaptic vesicle recycling.

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Caenorhabditis elegans Intersectin: A Synaptic Protein Regulating Neurotransmission

Molecular Biology of the Cell ◽

10.1091/mbc.e07-05-0460 ◽

2007 ◽

Vol 18 (12) ◽

pp. 5091-5099 ◽

Cited By ~ 17

Author(s):

Simon Rose ◽

Maria Grazia Malabarba ◽

Claudia Krag ◽

Anna Schultz ◽

Hanako Tsushima ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Synaptic Vesicle ◽

Regulatory Role ◽

Actin Dynamics ◽

Synaptic Vesicle Recycling ◽

Multifunctional Protein ◽

C Elegans ◽

Vesicle Recycling ◽

Negative Regulatory Role

Intersectin is a multifunctional protein that interacts with components of the endocytic and exocytic pathways, and it is also involved in the control of actin dynamics. Drosophila intersectin is required for viability, synaptic development, and synaptic vesicle recycling. Here, we report the characterization of intersectin function in Caenorhabditis elegans. Nematode intersectin (ITSN-1) is expressed in the nervous system, and it is enriched in presynaptic regions. The C. elegans intersectin gene (itsn-1) is nonessential for viability. In addition, itsn-1-null worms do not display any evident phenotype, under physiological conditions. However, they display aldicarb-hypersensitivity, compatible with a negative regulatory role of ITSN-1 on neurotransmission. ITSN-1 physically interacts with dynamin and EHS-1, two proteins involved in synaptic vesicle recycling. We have previously shown that EHS-1 is a positive modulator of synaptic vesicle recycling in the nematode, likely through modulation of dynamin or dynamin-controlled pathways. Here, we show that ITSN-1 and EHS-1 have opposite effects on aldicarb sensitivity, and on dynamin-dependent phenotypes. Thus, the sum of our results identifies dynamin, or a dynamin-controlled pathway, as a potential target for the negative regulatory role of ITSN-1.

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