| Abstract No.: | A-A1003 |
| Country: | Canada |
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| Title: | REQUIREMENT OF SLITS AND ROBO-2 IN THE SEGREGATION OF BASAL VOMERONASAL NEURON AXONS TO THE ACCESSORY OLFACTORY BULB |
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| Authors/Affiliations: | 1 Janet Prince*; 1 Jean-François Cloutier;
1 Montreal Neurological Institute, McGill University; Montreal, QC, Canada
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| Content: | The establishment of proper connectivity in the nervous system is essential for its function. In sensory systems, neurons in the periphery must project axons into exact locations in the CNS so that sensory stimuli can be translated into neural information. The olfactory systems play a critical role in the survival and mating behavior of most terrestrial vertebrates. While the main olfactory system is involved in the detection of odorants, the accessory olfactory system (AOS) detects pheromones and dictates innate actions. In both systems, axons of chemosensory neurons form stereotypic connections with higher-order neurons in the CNS. The formation of these connections is essential for olfactory function and relies on axon guidance molecules to direct pathfinding axons to
their correct targets.
The mechanisms involved in directing the formation of precise connections between sensory neurons in the vomeronasal organ (VNO) and their target field, the accessory olfactory bulb (AOB), are not yet fully understood. We have previously shown that the secreted semaphorin receptor, Npn-2, can regulate the targeting of apical vomeronasal neuron axons to the anterior part of the AOB. We are interested in defining the axon guidance cues that can promote the targeting of basal VNO neuron axons to the posterior AOB. We have examined the pattern of expression of Slit family members and their receptors, Robos, in the AOS. We have shown that Robo-2 expression is restricted to basal vomeronasal neurons and that Slits are expressed in the AOB. To evaluate the role of Slits and Robos in this system, we have analyzed vomeronasal projections in mice lacking Slit family members or Robo-2. We have shown that ablating expression of Robo-2 in vivo in vomeronasal neurons leads to mistargeting of a sub-population of vomeronasal neuron axons to the anterior region of the AOB. Similar defects are observed in Slit mutant mice demonstrating that Slit-Robo-2 interactions are required for the accurate segregation of vomeronasal projections within two specific regions of the AOB.
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