scholarly journals Ultrafast endocytosis at Caenorhabditis elegans neuromuscular junctions

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Shigeki Watanabe ◽  
Qiang Liu ◽  
M Wayne Davis ◽  
Gunther Hollopeter ◽  
Nikita Thomas ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Motor Neurons ◽  
Synaptic Vesicles ◽  
Neuromuscular Junctions ◽  
Light Stimulus ◽  
Single Stimulus ◽  
Vesicle Recycling ◽  
Ultrastructural Studies ◽  
Millisecond Time Scale ◽  
Intense Stimulation

Synaptic vesicles can be released at extremely high rates, which places an extraordinary demand on the recycling machinery. Previous ultrastructural studies of vesicle recycling were conducted in dissected preparations using an intense stimulation to maximize the probability of release. Here, a single light stimulus was applied to motor neurons in intact Caenorhabditis elegans nematodes expressing channelrhodopsin, and the animals rapidly frozen. We found that docked vesicles fuse along a broad active zone in response to a single stimulus, and are replenished with a time constant of about 2 s. Endocytosis occurs within 50 ms adjacent to the dense projection and after 1 s adjacent to adherens junctions. These studies suggest that synaptic vesicle endocytosis may occur on a millisecond time scale following a single physiological stimulus in the intact nervous system and is unlikely to conform to current models of endocytosis.

scholarly journals μ2 adaptin facilitates but is not essential for synaptic vesicle recycling in Caenorhabditis elegans

2008 ◽  
Vol 183 (5) ◽  
pp. 881-892 ◽  
Author(s):  
Mingyu Gu ◽  
Kim Schuske ◽  
Shigeki Watanabe ◽  
Qiang Liu ◽  
Paul Baum ◽  
...  
Keyword(s):  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Evoked Responses ◽  
Nematode Caenorhabditis Elegans ◽  
Synaptic Vesicle Recycling ◽  
Specific Loss ◽  
Vesicle Recycling ◽  
Cargo Proteins

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.

scholarly journals Intermediate filament accumulation can stabilize microtubules in Caenorhabditis elegans motor neurons

2018 ◽  
Vol 115 (12) ◽  
pp. 3114-3119 ◽  
Author(s):  
Naina Kurup ◽  
Yunbo Li ◽  
Alexandr Goncharov ◽  
Yishi Jin
Keyword(s):  
Caenorhabditis Elegans ◽  
Motor Neurons ◽  
Synaptic Connections ◽  
Motor Neuron Diseases ◽  
Genetic Ablation ◽  
Ultrastructural Studies ◽  
Cellular Machinery ◽  
Human Motor ◽  
The Impact ◽  
Axonal Swellings

Neural circuits utilize a coordinated cellular machinery to form and eliminate synaptic connections, with the neuronal cytoskeleton playing a prominent role. During larval development of Caenorhabditis elegans, synapses of motor neurons are stereotypically rewired through a process facilitated by dynamic microtubules (MTs). Through a genetic suppressor screen on mutant animals that fail to rewire synapses, and in combination with live imaging and ultrastructural studies, we find that intermediate filaments (IFs) stabilize MTs to prevent synapse rewiring. Genetic ablation of IFs or pharmacological disruption of IF networks restores MT growth and rescues synapse rewiring defects in the mutant animals, indicating that IF accumulation directly alters MT stability. Our work sheds light on the impact of IFs on MT dynamics and axonal transport, which is relevant to the mechanistic understanding of several human motor neuron diseases characterized by IF accumulation in axonal swellings.

scholarly journals A new probe for super-resolution imaging of membranes elucidates trafficking pathways

2014 ◽  
Vol 205 (4) ◽  
pp. 591-606 ◽  
Author(s):  
Natalia H. Revelo ◽  
Dirk Kamin ◽  
Sven Truckenbrodt ◽  
Aaron B. Wong ◽  
Kirsten Reuter-Jessen ◽  
...  
Keyword(s):  
Synaptic Vesicles ◽  
Cultured Cells ◽  
Neuromuscular Junctions ◽  
Organ Of Corti ◽  
Super Resolution ◽  
Molecular Composition ◽  
Cultured Neurons ◽  
Vesicle Recycling ◽  
Resolution Imaging ◽  
Super Resolution Microscopy

The molecular composition of the organelles involved in membrane recycling is difficult to establish as a result of the absence of suitable labeling tools. We introduce in this paper a novel probe, named membrane-binding fluorophore-cysteine-lysine-palmitoyl group (mCLING), which labels the plasma membrane and is taken up during endocytosis. It remains attached to membranes after fixation and permeabilization and can therefore be used in combination with immunostaining and super-resolution microscopy. We applied mCLING to mammalian-cultured cells, yeast, bacteria, primary cultured neurons, Drosophila melanogaster larval neuromuscular junctions, and mammalian tissue. mCLING enabled us to study the molecular composition of different trafficking organelles. We used it to address several questions related to synaptic vesicle recycling in the auditory inner hair cells from the organ of Corti and to investigate molecular differences between synaptic vesicles that recycle actively or spontaneously in cultured neurons. We conclude that mCLING enables the investigation of trafficking membranes in a broad range of preparations.

scholarly journals Mutations in Synaptojanin Disrupt Synaptic Vesicle Recycling

2000 ◽  
Vol 150 (3) ◽  
pp. 589-600 ◽  
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.

The Circuit for Chemotaxis and Exploratory Behavior in Caenorhabditis Elegans

2017 ◽  
pp. 369-376
Author(s):  
Cornelia I. Bargmann
Keyword(s):  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Sensory Neurons ◽  
Motor Neurons ◽  
Neuromuscular Junctions ◽  
Wiring Diagram ◽  
C Elegans ◽  
Section Electron ◽  
Adult Hermaphrodite ◽  
Electrophysiological Characterization

A wiring diagram of the Caenorhabditis elegans nervous system was constructed from serial-section electron micrographs 30 years ago. This wiring diagram divides the 302 neurons in the nervous system of the adult hermaphrodite into three overall classes: sensory neurons, motor neurons that form neuromuscular junctions, and interneurons that connect sensory neurons with motor neurons. Most sensory neurons and interneurons belong to bilaterally symmetric pairs with similar connections and morphologies, while motor neurons belong to larger classes. The C. elegans nervous system presents an exceptional situation in which neuroanatomical connections are extremely well defined and reproducible among animals. These detailed anatomical studies and a parallel genetic attack have increasingly been joined by functional and electrophysiological characterization.

Co-Culture of ES Cell-Derived Motor Neurons and Myotubes Show the Formation of Neuromuscular Junctions and Changes in Gene Expression

2006 ◽  
Vol 22 (06) ◽  
Author(s):  
Aleid Ruijs ◽  
Tateki Kubo ◽  
Jae Song ◽  
Milan Ranka ◽  
Mark Randolph ◽  
...  
Keyword(s):  
Gene Expression ◽  
Motor Neurons ◽  
Neuromuscular Junctions ◽  
Es Cell

The Caenorhabditis elegans odr-2 Gene Encodes a Novel Ly-6-Related Protein Required for Olfaction

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 211-224 ◽  
Author(s):  
Joseph H Chou ◽  
Cornelia I Bargmann ◽  
Piali Sengupta
Keyword(s):  
Caenorhabditis Elegans ◽  
Motor Neurons ◽  
Amino Terminus ◽  
Signaling Proteins ◽  
Related Protein ◽  
Olfactory Neurons ◽  
Unique Role ◽  
C Elegans ◽  
Founding Member ◽  
High Concentrations

Abstract Caenorhabditis elegans odr-2 mutants are defective in the ability to chemotax to odorants that are recognized by the two AWC olfactory neurons. Like many other olfactory mutants, they retain responses to high concentrations of AWC-sensed odors; we show here that these residual responses are caused by the ability of other olfactory neurons (the AWA neurons) to be recruited at high odor concentrations. odr-2 encodes a membrane-associated protein related to the Ly-6 superfamily of GPI-linked signaling proteins and is the founding member of a C. elegans gene family with at least seven other members. Alternative splicing of odr-2 yields three predicted proteins that differ only at the extreme amino terminus. The three isoforms have different promoters, and one isoform may have a unique role in olfaction. An epitope-tagged ODR-2 protein is expressed at high levels in sensory neurons, motor neurons, and interneurons and is enriched in axons. The AWC neurons are superficially normal in their development and structure in odr-2 mutants, but their function is impaired. Our results suggest that ODR-2 may regulate AWC signaling within the neuronal network required for chemotaxis.

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