ZFIN ID: ZDB-PUB-070614-23
Cxcl12/Cxcr4 chemokine signaling is required for placode assembly and sensory axon pathfinding in the zebrafish olfactory system
Miyasaka, N., Knaut, H., and Yoshihara, Y.
Date: 2007
Source: Development (Cambridge, England)   134(13): 2459-2468 (Journal)
Registered Authors: Knaut, Holger, Miyasaka, Nobuhiko, Yoshihara, Yoshihiro
Keywords: Stromal cell-derived factor-1 (SDF-1), GPCR, Cell migration, Axon guidance, Pioneer axons, Zebrafish
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Axons/metabolism*
  • Chemokine CXCL12
  • Chemokines, CXC/genetics
  • Chemokines, CXC/metabolism*
  • Gene Expression Regulation, Developmental
  • Mutation/genetics
  • Neurons, Afferent/metabolism*
  • Olfactory Pathways/cytology
  • Olfactory Pathways/embryology
  • Olfactory Pathways/metabolism*
  • Phenotype
  • Receptors, CXCR4/genetics
  • Receptors, CXCR4/metabolism*
  • Signal Transduction*
  • Zebrafish/embryology
  • Zebrafish/genetics
  • Zebrafish/metabolism*
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism
PubMed: 17537794 Full text @ Development
Positioning neurons in the right places and wiring axons to the appropriate targets are essential events for establishment of neural circuits. In the zebrafish olfactory system, precursors of olfactory sensory neurons (OSNs) assemble into a compact cluster to form the olfactory placode. Subsequently, OSNs differentiate and extend their axons to the presumptive olfactory bulb with high precision. In this study, we aim to elucidate the molecular mechanism underlying these two developmental processes. cxcr4b, encoding a chemokine receptor, is expressed in the migrating olfactory placodal precursors, and cxcl12a (SDF-1a), encoding a ligand for Cxcr4b, is expressed in the abutting anterior neural plate. The expression of cxcr4b persists in the olfactory placode at the initial phase of OSN axon pathfinding. At this time, cxcl12a is expressed along the placode-telencephalon border and at the anterior tip of the telencephalon, prefiguring the route and target of OSN axons, respectively. Interfering with Cxcl12a/Cxcr4b signaling perturbs the assembly of the olfactory placode, resulting in the appearance of ventrally displaced olfactory neurons. Moreover, OSN axons frequently fail to exit the olfactory placode and accumulate near the placode-telencephalon border in the absence of Cxcr4b-mediated signaling. These data indicate that chemokine signaling contributes to both the olfactory placode assembly and the OSN axon pathfinding in zebrafish.