Genetic analysis of growth cone migrations in Caenorhabditis elegans.
Model organisms like Caenorhabditis elegans allow the study of growth cone motility and guidance in vivo. We are using circumferential axon guidance in C. elegans to study both the mechanisms of guidance and the interactions between different guidance systems in vivo. A genetic screen has identified suppressors of the specific axon guidance defects caused by ectopic expression of UNC-5, the repulsive receptor for the UNC-6/netrin guidance cue. These mutations identify eight genes whose products are required for the function of UNC-5 in these cells. In principle, the functions of some of these genes may involve unc-73, which encodes a multidomain, cytoplasmic protein that is an activator of the rac and rho GTPases. Loss of UNC-73 causes errors in axon guidance, and it is hypothesized that UNC-73 acts in multiple signaling pathways used by guidance receptors on the growth cone surface to regulate the underlying cytoskeleton. Here we summarize and discuss these recent developments that are advancing our understanding of growth cone signal transduction in vivo.
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, and Department of Medical and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Canada M5G 1X5.
D C
DC
Merz
J G
JG
Culotti
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D002465:Cell Movement / Q000235:genetics*; D020439:Growth Cones / Q000737:chemistry / Q000502:physiology*; D015801:Helminth Proteins / Q000235:genetics; D009154:Mutation / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics; D009474:Neurons / Q000737:chemistry / Q000648:ultrastructure
D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D009419:Nerve Tissue Proteins; C111263:UNC-73 protein, C elegans