title: Ectopic expression in the giant fiber system of Drosophila reveals distinct roles for roundabout (Robo), Robo2, and Robo3 in dendritic guidance and synaptic connectivity.
abstract: The Roundabout (Robo) receptors have been intensively studied for their role in regulating axon guidance in the embryonic nervous system, whereas a role in dendritic guidance has not been explored. In the adult giant fiber system of Drosophila, we have revealed that ectopic Robo expression can regulate the growth and guidance of specific motor neuron dendrites, whereas Robo2 and Robo3 have no effect. We also show that the effect of Robo on dendritic guidance can be suppressed by Commissureless coexpression. Although we confirmed a role for all three Robo receptors in giant fiber axon guidance, the strong axon guidance alterations caused by overexpression of Robo2 or Robo3 have no effect on synaptic connectivity. In contrast, Robo overexpression in the giant fiber seems to directly interfere with synaptic function. We conclude that axon guidance, dendritic guidance, and synaptogenesis are separable processes and that the different Robo family members affect them distinctly.
authors.affiliation: Department of Biology, Morrill Science Center, University of Massachusetts, Amherst, Massachusetts 01003, USA.
authors.forename: Tanja A
authors.initials: TA
authors.lastname: Godenschwege
authors.forename: Julie H
authors.initials: JH
authors.lastname: Simpson
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Shan
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Bashaw
authors.forename: Corey S
authors.initials: CS
authors.lastname: Goodman
authors.forename: Rodney K
authors.initials: RK
authors.lastname: Murphey
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000502:physiology; D003712:Dendrites / Q000502:physiology*; D004330:Drosophila; D029721:Drosophila Proteins; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D015870:Gene Expression; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D009046:Motor Neurons / Q000378:metabolism; D009412:Nerve Fibers / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D010641:Phenotype; D011679:Pupa / Q000378:metabolism; D011930:Reaction Time / Q000502:physiology; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000235:genetics; D013569:Synapses / Q000502:physiology*; D000097905:Roundabout Proteins
chemical_list: D029721:Drosophila Proteins; D019476:Insect Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; C421243:Robo2 protein, Drosophila; C110665:comm protein, Drosophila; C421244:robo3 protein, Drosophila; C066819:sli protein, Drosophila