Latrotoxin receptor signaling engages the UNC-13-dependent vesicle-priming pathway in C. elegans.
alpha-latrotoxin (LTX), a 120 kDa protein in black widow spider venom, triggers massive neurotransmitter exocytosis. Previous studies have highlighted a role for both intrinsic pore-forming activity and receptor binding in the action of this toxin. Intriguingly, activation of a presynaptic G protein-coupled receptor, latrophilin, may trigger release independent of pore-formation. Here we have utilized a previously identified ligand of nematode latrophilin, emodepside, to define a latrophilin-dependent pathway for neurotransmitter release in C. elegans. In the pharyngeal nervous system of this animal, emodepside (100 nM) stimulates exocytosis and elicits pharyngeal paralysis. The pharynxes of animals with latrophilin (lat-1) gene knockouts are resistant to emodepside, indicating that emodepside exerts its high-affinity paralytic effect through LAT-1. The expression pattern of lat-1 supports the hypothesis that emodepside exerts its effect on the pharynx primarily via neuronal latrophilin. We build on these observations to show that pharynxes from animals with either reduction or loss of function mutations in Gq, phospholipaseC-beta, and UNC-13 are resistant to emodepside. The latter is a key priming molecule essential for synaptic vesicle-mediated release of neurotransmitter. We conclude that the small molecule ligand emodepside triggers latrophilin-mediated exocytosis via a pathway that engages UNC-13-dependent vesicle priming.
Neurosciences Research Group, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, United Kingdom.
James
J
Willson
Kiran
K
Amliwala
Andrew
A
Davis
Alan
A
Cook
Matthew F
MF
Cuttle
Neline
N
Kriek
Neil A
NA
Hopper
Vincent
V
O'Connor
Achim
A
Harder
Robert J
RJ
Walker
Lindy
L
Holden-Dye
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D002352:Carrier Proteins; D017931:DNA Primers; D047630:Depsipeptides; D005089:Exocytosis / Q000502:physiology*; D017353:Gene Deletion; D015870:Gene Expression; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D008969:Molecular Sequence Data; D018377:Neurotransmitter Agents / Q000378:metabolism; D010456:Peptides, Cyclic / Q000737:chemistry / Q000378:metabolism*; D034622:RNA Interference; D018000:Receptors, Peptide / Q000235:genetics* / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000502:physiology*; D013111:Spider Venoms / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D017931:DNA Primers; D047630:Depsipeptides; D008164:Luminescent Proteins; D018377:Neurotransmitter Agents; D010456:Peptides, Cyclic; D018000:Receptors, Peptide; D013111:Spider Venoms; C034800:alpha-latrotoxin receptor; C083141:phorbol ester binding protein; D049452:Green Fluorescent Proteins; C468987:emodepside