title: The Odorant Receptor-Dependent Role of Olfactory Marker Protein in Olfactory Receptor Neurons.
abstract: Olfactory receptor neurons (ORNs) in the nasal cavity detect and transduce odorants into action potentials to be conveyed to the olfactory bulb. Odorants are delivered to ORNs via the inhaled air at breathing frequencies that can vary from 2 to 10 Hz in the mouse. Thus olfactory transduction should occur at sufficient speed such that it can accommodate repetitive and frequent stimulation. Activation of odorant receptors (ORs) leads to adenylyl cyclase III activation, cAMP increase, and opening of cyclic nucleotide-gated channels. This makes the kinetic regulation of cAMP one of the important determinants for the response time course. We addressed the dynamic regulation of cAMP during the odorant response and examined how basal levels of cAMP are controlled. The latter is particularly relevant as basal cAMP depends on the basal activity of the expressed OR and thus varies across ORNs. We found that olfactory marker protein (OMP), a protein expressed in mature ORNs, controls both basal and odorant-induced cAMP levels in an OR-dependent manner. Lack of OMP increases basal cAMP, thus abolishing differences in basal cAMP levels between ORNs expressing different ORs. Moreover, OMP speeds up signal transduction for ORNs to better synchronize their output with high-frequency stimulation and to perceive brief stimuli. Last, OMP also steepens the dose-response relation to improve concentration coding although at the cost of losing responses to weak stimuli. We conclude that OMP plays a key regulatory role in ORN physiology by controlling multiple facets of the odorant response.
authors.affiliation: Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104-3308.
authors.forename: Michele
authors.initials: M
authors.lastname: Dibattista
authors.affiliation: Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104-3308 jreisert@monell.org.
authors.forename: Johannes
authors.initials: J
authors.lastname: Reisert
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D009544:Niflumic Acid / Q000494:pharmacology; D009812:Odorants; D051842:Olfactory Marker Protein / Q000235:genetics / Q000378:metabolism; D009831:Olfactory Mucosa / Q000166:cytology; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology
chemical_list: D000276:Adjuvants, Immunologic; D016861:Cyclooxygenase Inhibitors; D051842:Olfactory Marker Protein; C497598:Omp protein, mouse; D010726:Phosphodiesterase Inhibitors; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D005576:Colforsin; D009544:Niflumic Acid; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine
keywords: olfactory; olfactory receptor neurons; olfactory signal transduction