Voltage-gated calcium channels direct neuronal migration in Caenorhabditiselegans

Calcium signaling is known to be important for regulating the guidance of m igrating neurons, yet the molecular mechanisms underlying this process are not well understood. We have found that two different voltage-gated calcium channels are important for the accurate guidance of postembryonic neuronal migrations in the nematode Caenorhabditis elegans. In mutants carrying los s of function alleles of the calcium channel gene unc-2, the touch receptor neuron AVM and the interneuron SDQR often migrated inappropriately, leadin g to misplacement of their cell bodies. However, the AVM neurons in unc-2 m utant animals extended axons in a wild-type pattern, suggesting that the UN C-2 calcium channel specifically directs migration of the neuronal cell bod y and is not required for axonal pathfinding. In contrast, mutations in egl -19, which affect a different voltage-gated calcium channel, affected the m igration of the AVM and SDQR bodies, as well as the guidance of the AVM axo n. Thus, cell migration and axonal pathfinding in the AVM neurons appear to involve distinct calcium channel subtypes. Mutants defective in the unc-43 /CaM kinase gene showed a defect in SDQR and AVM positioning that resembled that of unc-2 mutants; thus, CaM kinase may function as an effector of the UNC-2-mediated calcium influx in guiding cell migration. (C) 2000 Academic Press.