Robos and slits control the pathfinding and targeting of mouse olfactory sensory axons.
Odorants are detected by olfactory receptor neurons (ORNs) located in the olfactory epithelium. In mice, ORNs expressing the same odorant receptor (OR) project to a single glomerulus out of 1800 in the olfactory bulb (OB). It has been proposed that OR-derived cAMP signals guide ORN axons to their glomeruli rather than OR themselves. Recently, it has also been shown that the axon guidance molecule Slit1 and its receptor Robo2 control the dorsoventral segregation of ORN axons as they are projecting to the OB. We have analyzed the development of olfactory projections in Slit1/Slit2 and Robo1/Robo2 single and double mutants. We show that in Robo1-/-;Robo2-/- mice, most ORN axons fail to enter the OB and instead project caudally into the diencephalon. Moreover, in these mice, ORN axons expressing the same OR project to several glomeruli at ectopic positions. Thus, Slit1, Slit2, Robo1, and Robo2 cooperate to control the convergence of ORN axons to the OB and the precise targeting of ORN axons to specific glomeruli.
Nguyen-Ba-Charvet
Kim T
KT
Université Pierre et Marie Curie and Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7102, F-75005 Paris, France.
Di Meglio
Thomas
T
Fouquet
Coralie
C
Chédotal
Alain
A
D000818:Animals; D001369:Axons / Q000502:physiology; D005260:Female; D036341:Intercellular Signaling Peptides and Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D009830:Olfactory Bulb / Q000196:embryology / Q000502:physiology; D009833:Olfactory Pathways / Q000196:embryology / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000196:embryology / Q000502:physiology*; D011247:Pregnancy; D011971:Receptors, Immunologic / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein
D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein; C498888:Robo2 protein, mouse; C120010:Slit1 protein, mouse