First published online June 11, 2007
Development 134, 1304e (2007)
© The Company of Biologists Limited
Bifunctional chemokine signalling
Cell positioning and axon pathfinding establish neural circuits in the
developing nervous system. Previous fate-mapping studies in zebrafish have
revealed that olfactory sensory neuron (OSN) precursors along the anterior
neural plate converge - via the action of unknown factors - to form the
olfactory placode. Miyasaka et al. now report on
p. 2459 that, in
zebrafish, Cxcl12/Cxcr4 chemokine signalling mediates both the olfactory
placode assembly and the correct projection of differentiated OSN axons to the
olfactory bulb. In odysseus (ody) zebrafish mutants (in
which Cxcr4b receptor function is lost), olfactory placode assembly is
perturbed, olfactory neurons displace ventrally and OSN axons fail to exit the
placode, and instead accumulate near the placode-telencephalon border. The
misexpression of the Cxcl12 ligand (ubiquitously and in mosaics) in zebrafish
embryos also perturbs placode formation. The role of Cxcr4 signalling in
zebrafish has some similarities to its role in mice, where it regulates motor
axon projections. Perhaps, the authors suggest, Cxcl12/Cxcr4 chemokine
signalling creates a favourable environment for initial axonal trajectories in
vertebrates.

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Related articles in Development:
- Cxcl12/Cxcr4 chemokine signaling is required for placode assembly and sensory axon pathfinding in the zebrafish olfactory system
- Nobuhiko Miyasaka, Holger Knaut, and Yoshihiro Yoshihara
Development 2007 134: 2459-2468.
[Abstract]
[Full Text]