title: Glial and neuronal Semaphorin signaling instruct the development of a functional myotopic map for Drosophila walking.
abstract: Motoneurons developmentally acquire appropriate cellular architectures that ensure connections with postsynaptic muscles and presynaptic neurons. In Drosophila, leg motoneurons are organized as a myotopic map, where their dendritic domains represent the muscle field. Here, we investigate mechanisms underlying development of aspects of this myotopic map, required for walking. A behavioral screen identified roles for Semaphorins (Sema) and Plexins (Plex) in walking behavior. Deciphering this phenotype, we show that PlexA/Sema1a mediates motoneuron axon branching in ways that differ in the proximal femur and distal tibia, based on motoneuronal birth order. Importantly, we show a novel role for glia in positioning dendrites of specific motoneurons; PlexB/Sema2a is required for dendritic positioning of late-born motoneurons but not early-born motoneurons. These findings indicate that communication within motoneurons and between glia and motoneurons, mediated by the combined action of different Plexin/Semaphorin signaling systems, are required for the formation of a functional myotopic map.
authors.affiliation: National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
authors.forename: Durafshan Sakeena
authors.initials: DS
authors.lastname: Syed
authors.affiliation: National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.|Manipal University, Manipal, India.
authors.forename: Swetha B M
authors.initials: SB
authors.lastname: Gowda
authors.affiliation: National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
authors.forename: O Venkateswara
authors.initials: OV
authors.lastname: Reddy
authors.affiliation: Biozentrum, University of Basel, Basel, Switzerland.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Reichert
authors.affiliation: National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
authors.forename: K
authors.identifier: http://orcid.org/0000-0002-4705-5629
authors.initials: K
authors.lastname: VijayRaghavan
mesh_terms: D000818:Animals; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins / Q000378:metabolism; D009046:Motor Neurons / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009457:Neuroglia / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D039961:Semaphorins / Q000378:metabolism*; D015398:Signal Transduction; D016138:Walking
chemical_list: D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface; D039961:Semaphorins; C116483:plexA protein, Drosophila; C477531:semaphorin 1a, Drosophila
keywords: <i>d. melanogaster</i>; developmental biology; glia; motor neurons; myotopic map; neuron targeting; neuroscience; semaphorin; stem cells