title: Hierarchical axon targeting of Drosophila olfactory receptor neurons specified by the proneural transcription factors Atonal and Amos.
abstract: Sensory information is spatially represented in the brain to form a neural map. It has been suggested that axon-axon interactions are important for neural map formation; however, the underlying mechanisms are not fully understood. We used the Drosophila antennal lobe, the first olfactory center in the brain, as a model for studying neural map formation. Olfactory receptor neurons (ORNs) expressing the same odorant receptor target their axons to a single glomerulus out of approximately 50 glomeruli in the antennal lobe. Previous studies have showed that the axons of Atonal ORNs, specified by Atonal, a basic helix-loop-helix (bHLH) transcription factor, pioneer antennal lobe formation; however, the details remain to be elucidated. Here, we show that genetic ablation of Atonal ORNs affects antennal lobe structure and axon targeting of Amos ORNs, another type of ORN specified by the bHLH transcription factor Amos. During development, Atonal ORNs reach the antennal lobe and form the axon commissure before Amos ORNs. We also found that N-cadherin knockdown specifically in Atonal ORNs disrupts the glomerular boundary in the whole antennal lobe. Our results suggest that Atonal ORNs function as pioneer axons. Thus, correct axon targeting of Atonal ORNs is essential for formation of the whole antennal lobe.
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan.
authors.forename: Misako
authors.initials: M
authors.lastname: Okumura
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan.|Core Research for Evolutional Science and Technology, Japan Agency for Medical Research and Development, Tokyo, 100-0004, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miura
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan.|Core Research for Evolutional Science and Technology, Japan Agency for Medical Research and Development, Tokyo, 100-0004, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Chihara
mesh_terms: D000818:Animals; D057506:Arthropod Antennae / Q000378:metabolism; D001369:Axons / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D009414:Nerve Growth Factors / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D018034:Olfactory Receptor Neurons / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D015820:Cadherins; D029721:Drosophila Proteins; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D014157:Transcription Factors; C405512:Amos protein, Drosophila; C082142:ato protein, Drosophila