BIG-2 mediates olfactory axon convergence to target glomeruli.
Olfactory sensory neurons expressing a given odorant receptor converge axons onto a few topographically fixed glomeruli in the olfactory bulb, leading to establishment of the odor map. Here, we report that BIG-2/contactin-4, an axonal glycoprotein belonging to the immunoglobulin superfamily, is expressed in a subpopulation of mouse olfactory sensory neurons. A mosaic pattern of glomerular arrangement is observed with strongly BIG-2-positive, weakly positive, and negative axon terminals in the olfactory bulb, which is overlapping but not identical with those of Kirrel2 and ephrin-A5. There is a close correlation between the BIG-2 expression level and the odorant receptor choice in individual sensory neurons. In BIG-2-deficient mice, olfactory sensory neurons expressing a given odorant receptor frequently innervate multiple glomeruli at ectopic locations. These results suggest that BIG-2 is one of the axon guidance molecules crucial for the formation and maintenance of functional odor map in the olfactory bulb.
Kaneko-Goto
Tomomi
T
Laboratory for Neurobiology of Synapse, RIKEN Brain Science Institute, Saitama 351-0198, Japan.
Yoshihara
Sei-Ichi
S
Miyazaki
Haruko
H
Yoshihara
Yoshihiro
Y
D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000502:physiology*; D015816:Cell Adhesion Molecules, Neuronal / Q000172:deficiency / Q000502:physiology*; D058966:Contactins; D036386:Ephrin-A5 / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D016296:Mutagenesis / Q000502:physiology; D009415:Nerve Net / Q000502:physiology; D009830:Olfactory Bulb / Q000166:cytology*; D051842:Olfactory Marker Protein / Q000235:genetics / Q000378:metabolism; D009832:Olfactory Nerve / Q000378:metabolism; D061219:Olfactory Nerve Injuries; D018034:Olfactory Receptor Neurons / Q000166:cytology* / Q000378:metabolism*
D015816:Cell Adhesion Molecules, Neuronal; C484359:Cntn4 protein, mouse; D058966:Contactins; D036386:Ephrin-A5; D008565:Membrane Proteins; D051842:Olfactory Marker Protein