Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710.
Tokyo University of Agriculture and Technology, Tokyo 183-8538, Japan.
eNeuro. 2020 Apr 23;7(2). doi: 10.1523/ENEURO.0103-19.2019. Print 2020 Mar/Apr.
A fundamental challenge in studying principles of organization used by the olfactory system to encode odor concentration information has been identifying 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 this study, we characterized the mouse OR repertoires activated by the two odorants, acetophenone (ACT) and 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), 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 ACT. Using a mouse line that genetically labels Olfr923-positive axons, we provided evidence that ACT activates the Olfr923 glomeruli in the olfactory bulb. Through molecular dynamics stimulations, we identified amino acid residues in the Olfr923 binding cavity that facilitate ACT binding. This study sheds light on the active process by which unique OR repertoires may collectively facilitate the discrimination of odorant concentrations.
研究嗅觉系统用于编码气味浓度信息的组织原理的一个基本挑战是，在自由活动的动物体内，确定在广泛浓度范围内全面激活的气味受体 (OR) 集合。在哺乳动物中，最近使用基于高通量测序的方法使得这一点变得可行，这些方法可以识别激活的 OR 群体。在这项研究中，我们使用磷酸化核糖体蛋白 S6 捕获 followed by RNA-Seq 的方法，从 0.01%到 100%（v/v）的起始浓度，表征了两种气味剂丙酮 (ACT) 和 2,5-二氢-2,4,5-三甲基噻唑啉 (TMT) 激活的小鼠 OR 基因库。我们发现 Olfr923 是对 ACT 富集的最敏感的 OR 之一。使用一种遗传标记 Olfr923 阳性轴突的小鼠系，我们提供了 ACT 激活嗅球中 Olfr923 神经小球的证据。通过分子动力学刺激，我们确定了 Olfr923 结合腔内促进 ACT 结合的氨基酸残基。这项研究揭示了独特的 OR 基因库可能共同促进气味浓度识别的活跃过程。
