title: A G protein/cAMP signal cascade is required for axonal convergence into olfactory glomeruli.
abstract: The mammalian odorant receptors (ORs) comprise a large family of G protein-coupled receptors that are critical determinants of both the odorant response profile and the axonal identity of the olfactory sensory neurons in which they are expressed. Although the pathway by which ORs activate odor transduction is well established, the mechanism by which they direct axons into proper glomerular relationships remains unknown. We have developed a gain-of-function approach by using injection of retroviral vectors into the embryonic olfactory epithelium to study the ORs' contribution to axon guidance. By ectopically expressing ORs, we demonstrate that functional OR proteins induce axonal coalescence. Furthermore, ectopic expression of Galpha mutants reveals that activation of the signal transduction cascade is sufficient to cause axonal convergence into glomeruli. Analysis of Galpha subunit expression indicates that development and odorant transduction use separate transduction pathways. Last, we establish that the generation of cAMP through adenylyl cyclase 3 is necessary to establish proper axonal identity. Our data point to a model in which axonal sorting is accomplished by OR stimulation of cAMP production by coupling to Galphas.
authors.affiliation: Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027, USA
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Chesler
authors.forename: Dong-Jing
authors.initials: DJ
authors.lastname: Zou
authors.forename: Claire E
authors.initials: CE
authors.lastname: Le Pichon
authors.forename: Zita A
authors.initials: ZA
authors.lastname: Peterlin
authors.forename: Glennis A
authors.initials: GA
authors.lastname: Matthews
authors.forename: Xin
authors.initials: X
authors.lastname: Pei
authors.forename: Michael C
authors.initials: MC
authors.lastname: Miller
authors.forename: Stuart
authors.initials: S
authors.lastname: Firestein
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism*; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D051379:Mice; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism; D009830:Olfactory Bulb / Q000166:cytology* / Q000196:embryology / Q000378:metabolism*; D010641:Phenotype; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D015290:Second Messenger Systems
chemical_list: D043562:Receptors, G-Protein-Coupled; D000242:Cyclic AMP; D019204:GTP-Binding Proteins