title: Control of dendritic morphogenesis by Trio in Drosophila melanogaster.
abstract: Abl tyrosine kinase and its effectors among the Rho family of GTPases each act to control dendritic morphogenesis in Drosophila. It has not been established, however, which of the many GTPase regulators in the cell link these signaling molecules in the dendrite. In axons, the bifunctional guanine exchange factor, Trio, is an essential link between the Abl tyrosine kinase signaling pathway and Rho GTPases, particularly Rac, allowing these systems to act coordinately to control actin organization. In dendritic morphogenesis, however, Abl and Rac have contrary rather than reinforcing effects, raising the question of whether Trio is involved, and if so, whether it acts through Rac, Rho or both. We now find that Trio is expressed in sensory neurons of the Drosophila embryo and regulates their dendritic arborization. trio mutants display a reduction in dendritic branching and increase in average branch length, whereas over-expression of trio has the opposite effect. We further show that it is the Rac GEF domain of Trio, and not its Rho GEF domain that is primarily responsible for the dendritic function of Trio. Thus, Trio shapes the complexity of dendritic arbors and does so in a way that mimics the effects of its target, Rac.
authors.affiliation: Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Madhuri
authors.initials: M
authors.lastname: Shivalkar
authors.forename: Edward
authors.initials: E
authors.lastname: Giniger
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D003712:Dendrites / Q000378:metabolism* / Q000648:ultrastructure; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D009154:Mutation; D055495:Neurogenesis / Q000235:genetics / Q000502:physiology; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011984:Sensory Receptor Cells / Q000145:classification / Q000378:metabolism / Q000648:ultrastructure; D015398:Signal Transduction; D020744:rac GTP-Binding Proteins / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D020662:Guanine Nucleotide Exchange Factors; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; C490974:trio protein, Drosophila; D020744:rac GTP-Binding Proteins