title: Trpm5 expression in the olfactory epithelium.
abstract: The Ca2+-activated monovalent cation channel Trpm5 is a key element in chemotransduction of taste receptor cells of the tongue, but the extent to which Trpm5 channels are expressed in olfactory sensory neurons (OSNs) of the main olfactory epithelium (MOE) of adult mice as part of a specific pheromonal detection system is debated. Here, we used a novel Trpm5-IRES-Cre knockin strain to drive Cre recombinase expression, employed previously validated Trpm5 antibodies, performed in situ hybridization experiments to localize Trpm5 RNA, and searched extensively for Trpm5 splice variants in genetically-labeled, Trpm5-expressing MOE cells. In contrast to previous reports, we find no evidence for the existence in adult mouse OSNs of the classical Trpm5 channel known from taste cells. We show that Trpm5-expressing adult OSNs express a novel Trpm5 splice variant, Trpm5-9, that is unlikely to form a functional cation channel by itself. We also demonstrate that Trpm5 is transiently expressed in a subpopulation of mature OSNs in the embryonic olfactory epithelium, indicating that Trpm5 channels could play a specific role in utero during a narrow developmental time window. Ca2+imaging with GCaMP3 under the control of the Trpm5-IRES-Cre allele using a newly developed MOE wholemount preparation of the adult olfactory epithelium reveals that Trpm5-GCaMP3 OSNs comprise a heterogeneous group of sensory neurons many of which can detect general odorants. Together, these studies are essential for understanding the role of transient receptor potential channels in mammalian olfaction.
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Pyrski
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Eckstein
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schmid
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Bufe
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Weiss
authors.affiliation: Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Chubanov
authors.affiliation: Center for Molecular Signaling (PZMS), Saarland University, Homburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Boehm
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany. Electronic address: frank.zufall@uks.eu.
authors.forename: Frank
authors.initials: F
authors.lastname: Zufall
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D004622:Embryo, Mammalian; D019922:GAP-43 Protein / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008840:Microfilament Proteins / Q000378:metabolism; D051842:Olfactory Marker Protein / Q000235:genetics / Q000378:metabolism; D009831:Olfactory Mucosa / Q000166:cytology / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D018034:Olfactory Receptor Neurons / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism*; D019147:Vomeronasal Organ / Q000196:embryology / Q000254:growth & development / Q000378:metabolism
chemical_list: D019922:GAP-43 Protein; D008840:Microfilament Proteins; D051842:Olfactory Marker Protein; C497598:Omp protein, mouse; D012333:RNA, Messenger; D050053:TRPM Cation Channels; C498617:Trpm5 protein, mouse; C026615:villin; D049452:Green Fluorescent Proteins; D002118:Calcium
keywords: Odor detection; Olfactory system; Pheromonal sensing; TRP channel