control of dendritic morphogenesis by trio in drosophila melanogaster三控制的树突形态发生的黑腹果蝇.pdf

Control of Dendritic Morphogenesis by Trio in Drosophila melanogaster Madhuri Shivalkar, Edward Giniger* 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 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. Citation: Shivalkar M, Giniger E (2012) Control of Dendritic Morphogenesis by Trio in Drosophila melanogaster. PLoS ONE 7(3): e33737. doi:10.1371/ journal.pone.0033737 Editor: Bassem A. Hassan, VIB and KU Leuven, Belgium Received November 8, 2011; Accepted February 16, 2012;