A RHO GTPase-mediated pathway is required during P cell migration in Caenorhabditis elegans

The Rho family of guanine triphosphate hydrolases controls various cellular processes, including cell migration. We describe here the demonstration of a role for a RhoA GTPase homologue during cell migration in Caenorhabditis elegans. We show that eliminating or reducing rho-1 gene function by using a dominant-negative transgene or dsRNA interference results in a severe de fect in migration of hypodermal P cells to a ventral position. Biochemical and genetic data also suggest that unc-73, which encodes a Trio-like guanin e nucleotide exchange factor, may act as an activator of rho-1 in the migra tion process. Mutations in let-502 ROCK, a homologue of a RhoA effector in mammals, also cause defects in P cell migration, suggesting that it may be one of several effectors acting downstream of rho-1 during P cell migration . Finally, we provide evidence to support the idea that other small Rac sub family small GTPases act redundantly and in parallel to RHO-1 in this speci fic cell migration event.