Extrasynaptic acetylcholine signaling through a muscarinic receptor regulates cell migration.

Acetylcholine (ACh) promotes various cell migrations in vitro, but there are few investigations into this nonsynaptic role of ACh signaling in vivo. Here we investigate the function of a muscarinic receptor on an epithelial cell migration in Caenorhabditis elegans We show that the migratory gonad leader cell, the linker cell (LC), uses an M1/M3/M5-like muscarinic ACh receptor GAR-3 to receive extrasynaptic ACh signaling from cholinergic neurons for its migration. Either the loss of the GAR-3 receptor in the LC or the inhibition of ACh release from cholinergic neurons resulted in migratory path defects. The overactivation of the GAR-3 muscarinic receptor caused the LC to reverse its orientation through its downstream effectors Gαq/egl-30, PLCβ/egl-8, and TRIO/unc-73 This reversal response only occurred in the fourth larval stage, which corresponds to the developmental time when the GAR-3::yellow fluorescent protein receptor in the membrane relocalizes from a uniform to an asymmetric distribution. These findings suggest a role for the GAR-3 muscarinic receptor in determining the direction of LC migration.