title: NQO1 activity in the main and the accessory olfactory systems correlates with the zonal topography of projection maps.
abstract: The mouse olfactory epithelium (OE) is divided into spatial zones, each containing neurons expressing zone-specific subsets of odorant receptor genes. Likewise, the vomeronasal (VN) organ is organized into apical and basal subpopulations of neurons expressing different VN receptor gene families. Axons projecting from the different OE zones and VN subpopulations form synapses within circumscribed regions in the glomerular layer of the olfactory bulb (OB) and accessory olfactory bulb (AOB), respectively. We here show that mature neurons in one defined zone selectively express NADPH:quinone oxidoreductase (NQO1), an enzyme that catalyses reduction of quinones. Immunohistochemistry and in situ hybridization analyses show non-overlapping expression of NQO1 and the Rb8 neural cell adhesion molecule (RNCAM/OCAM) in OE and axon terminals within glomeruli of the OB. In addition, NQO1 immunoreactivity reveals selective, zone-specific axon fasciculation in the olfactory nerve. VN subpopulations do not show complementary patterns of RNCAM and NQO1 immunoreactivity, instead both genes are co-expressed in apical VN neurons that project to the rostral AOB. These results indicate that one division of both the accessory and the main olfactory projection maps are composed of sensory neurons that are specialized to reduce environmental and/or endogenously produced quinones via an NQO1-dependent mechanism. The role of NQO1 in bioactivation of quinoidal drugs also points to a connection between zone-specific NQO1 expression and zone-specific toxicity of certain olfactory toxins.
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, SE901 87, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Gussing
authors.forename: Staffan
authors.initials: S
authors.lastname: Bohm
mesh_terms: D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D019922:GAP-43 Protein / Q000378:metabolism; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D051267:NF-E2-Related Factor 2; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D009474:Neurons / Q000201:enzymology*; D009830:Olfactory Bulb / Q000166:cytology / Q000201:enzymology*; D009831:Olfactory Mucosa / Q000166:cytology* / Q000201:enzymology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D019147:Vomeronasal Organ / Q000166:cytology / Q000201:enzymology
chemical_list: C491123:BACH2 protein, human; C102109:Bach2 protein, mouse; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D019922:GAP-43 Protein; D044385:GTP-Binding Protein alpha Subunits; D051267:NF-E2-Related Factor 2; C108768:Ncam2 protein, mouse; D019006:Neural Cell Adhesion Molecules; C495636:Nfe2l2 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D009249:NADP; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human