A Neuronal Identity Code for the Odorant Receptor-Specific and Activity-Dependent Axon Sorting

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2006.10.031 Byline: Shou Serizawa (1)(2), Kazunari Miyamichi (1)(2), Haruki Takeuchi (1)(2), Yuya Yamagishi (1), Misao Suzuki (3), Hitoshi Sakano (1)(2) Abstract: In the mouse, olfactory sensory neurons (OSNs) expressing the same odorant receptor (OR) converge their axons to a specific set of glomeruli in the olfactory bulb. To study how OR-instructed axonal fasciculation is controlled, we searched for genes whose expression profiles are correlated with the expressed ORs. Using the transgenic mouse in which the majority of OSNs express a particular OR, we identified such genes coding for the homophilic adhesive molecules Kirrel2/Kirrel3 and repulsive molecules ephrin-A5/EphA5. In the CNGA2 knockout mouse, where the odor-evoked cation influx is disrupted, Kirrel2 and EphA5 were downregulated, while Kirrel3 and ephrin-A5 were upregulated, indicating that these genes are transcribed in an activity-dependent manner. Mosaic analysis demonstrated that gain of function of these genes generates duplicated glomeruli. We propose that a specific set of adhesive/repulsive molecules, whose expression levels are determined by OR molecules, regulate the axonal fasciculation of OSNs during the process of glomerular map formation. Author Affiliation: (1) Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan (2) CREST Program of Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan (3) Center for Animal Resources and Development, Kumamoto University, Kumamoto 862-0976, Japan Article History: Received 4 August 2006; Revised 14 September 2006; Accepted 18 October 2006 Article Note: (miscellaneous) Published: November 30, 2006