Olfactory marker protein (OMP) gene deletion causes altered physiological activity of olfactory sensory neurons.

Abstract

Olfactory marker protein (OMP) is an abundant, phylogenetically conserved, cytoplasmic protein of unknown function expressed almost exclusively in mature olfactory sensory neurons. To address its function, we generated OMP-deficient mice by gene targeting in embryonic stem cells. We report that these OMP-null mice are compromised in their ability to respond to odor stimuli, providing insight to OMP function. The maximal electroolfactogram response of the olfactory neuroepithelium to several odorants was 20-40% smaller in the mutants compared with controls. In addition, the onset and recovery kinetics following isoamyl acetate stimulation are prolonged in the null mice. Furthermore, the ability of the mutants to respond to the second odor pulse of a pair is impaired, over a range of concentrations, compared with controls. These results imply that neural activity directed toward the olfactory bulb is also reduced. The bulbar phenotype observed in the OMP-null mouse is consistent with this hypothesis. Bulbar activity of tyrosine hydroxylase, the rate limiting enzyme of catecholamine biosynthesis, and content of the neuropeptide cholecystokinin are reduced by 65% and 50%, respectively. This similarity to postsynaptic changes in gene expression induced by peripheral olfactory deafferentation or naris blockade confirms that functional neural activity is reduced in both the olfactory neuroepithelium and the olfactory nerve projection to the bulb in the OMP-null mouse. These observations provide strong support for the conclusion that OMP is a novel modulatory component of the odor detection/signal transduction cascade.

The olfactory bulb as an independent developmental domain

“…26 In general, deprivation commenced in postnatal/adult animals, when all the connections between the OE and the OB have already been established. Nevertheless, similar changes have been observed when odor-evoked signaling was genetically eliminated, before connections are established, for example in mice lacking either functional olfactory cyclic nucleotidegated channels 54 (Table 1), G (olf) , the major G protein a subunit in olfactory receptors 55 or OMP, the olfactory marker protein, which takes part in odor perception 56 (Table 1). Furthermore, some peripheral olfactory projections are affected in mice deficient for a cyclic nucleotidegated channel subunit, suggesting that the pathfinding of these axons is in part influenced by odorant-dependent activity.…”

Deletion of voltage‐gated channel affects glomerular refinement and odorant receptor expression in the mouse olfactory system

“…Although OMP is not classified as a signal transduction protein per se, loss of OMP in OSNs causes an overshooting of sensory axons into the external plexiform layer, which persists in mice up to 8 months of age (St. John and Key, 2005). Because mice with gene-targeted deletion of OMP have altered OSN electrophysiological function and an altered behavioral response to odorant stimulation (Buiakova et al, 1996;Youngentob and Margolis, 1999;Youngentob et al, 2001), it is an interesting parallel that Kv1.3-null animals (altered OB electrophysiological function and enhanced behavioral discrimination of odorants) also demonstrate fixed (up to 2 years) synaptic mistargeting in the form of supernumerary glomerular connections.How might mitral cell activity modulate the refinement of presynaptic OSNs? In other sensory systems, synapse formation is initially achieved by genetically determined cues, but subsequent refinement requires spontaneous neural activity and sensory experience (Katz and Shatz, 1996).…”

Identification of an olfactory imprinting-related gene in the lacustrine sockeye salmon, Oncorhynchus nerka

“…OMP is expressed almost exclusive in mature olfactory receptor cells and used as a molecular marker for recognizing theses cells in mammals (Johnson et al, 1993;Levai and Strotmann, 2003). Electrophysiological studies using OMP knockout mice suggest that OMP contributes to olfactory sensitivity (Buiakova et al, 1996;Ivic et al, 2000;Youngentob et al, 2001). In teleost, olfactory receptor cells of rainbow trout showed immunoreactivities of the OMP using anti-mammalian OMP sera (Riddle and Oakley, 1992).…”