Project description:A fundamental challenge in studying principles of organization used by the olfactory system to encode odor concentration information has been to identify comprehensive sets of activated odorant receptors (ORs) across a broad concentration range inside freely behaving animals. In mammals, this has recently become feasible with high-throughput sequencing-based methods that identify populations of activated ORs in vivo. In this study, we characterized the mouse OR repertoires activated by the two odorants, acetophenone and 2,5-dihydro-2,4,5-trimethylthiazoline, from 0.01% to 100% (v/v) as starting concentrations using phosphorylated ribosomal protein S6 capture followed by RNA-Seq. We found Olfr923 to be one of the most sensitive ORs that is enriched by acetophenone. Using a mouse line that genetically labels Olfr923-positive axons, we provided evidence that acetophenone activates the Olfr923 glomeruli in the olfactory bulb. Through molecular dynamics stimulations, we identified amino acid residues in the Olfr923 binding cavity that facilitates acetophenone binding. This study sheds light on the active process by which unique OR repertoires may collectively facilitate the discrimination of odorant concentrations.
Project description:Odorants are thought to activate sets of odorant receptors in vivo, but capturing sets of responsive receptors in vivo has never been accomplished. GeneChip microarrays were used to identify the odorant receptor mRNAs enriched in samples from activated olfactory neurons
Project description:We present a high-throughput in vivo method to identify odorant receptors responding to odorants, using phosphorylated ribosome immunoprecipitation of mRNA from olfactory epithelium of odor-stimulated mice followed by RNA-Seq. pS6-IP RNA-Seq in odor stimulated vs control mice olfactory epithelium
Project description:We present a high-throughput in vivo method to identify odorant receptors responding to odorants, using phosphorylated ribosome immunoprecipitation of mRNA from olfactory epithelium of odor-stimulated mice followed by RNA-Seq.
Project description:Olfactory sensory neurons express just one out of a possible ~1000 odorant receptor genes, reflecting an exquisite mode of gene regulation. In one model, once an odorant receptor is chosen for expression, other receptor genes are suppressed by a negative feedback mechanism, ensuring a stable functional identity of the sensory neuron for the lifetime of the cell. The signal transduction mechanism subserving odorant receptor gene silencing remains obscure, however. Here we demonstrate in the zebrafish that odorant receptor gene silencing is dependent on receptor activity. Moreover, we show that signaling through G protein M-NM-2M-NM-3 subunits is both necessary and sufficient to suppress the expression of odorant receptor genes, and likely acts through histone methylation to maintain the silenced odorant receptor genes in transcriptionally inactive heterochromatin. These results provide new insights linking receptor activity with the epigenetic mechanisms responsible for ensuring the expression of one odorant receptor per olfactory sensory neuron. Total 6 samples were analyzed-3 controls & 3 samples