Kang NaNa, Kim Hyerin, Jae YoonGyu, Lee NaHye, Ku Cheol Ryong, Margolis Frank, Lee Eun Jig, Bahk Young Yil, Kim Min-Soo, Koo JaeHyung
Department of Brain Science, DGIST, Daegu, Korea.
Department of Information and Communication Engineering, DGIST, Daegu, Korea.
PLoS One. 2015 Jan 30;10(1):e0116097. doi: 10.1371/journal.pone.0116097. eCollection 2015.
Olfactory receptor (OR)-associated events are mediated by well-conserved components in the olfactory epithelium, including olfactory G-protein (Golf), adenylate cyclase III (ACIII), and olfactory marker protein (OMP). The expression of ORs has recently been observed in non-olfactory tissues where they are involved in monitoring extracellular chemical cues. The large number of OR genes and their sequence similarities illustrate the need to find an effective and simple way to detect non-olfactory OR-associated events. In addition, expression profiles and physiological functions of ORs in non-olfactory tissues are largely unknown. To overcome limitations associated with using OR as a target protein, this study used OMP with Golf and ACIII as targets to screen for potential OR-mediated sensing systems in non-olfactory tissues. Here, we show using western blotting, real-time PCR, and single as well as double immunoassays that ORs and OR-associated proteins are co-expressed in diverse tissues. The results of immunohistochemical analyses showed OMP (+) cells in mouse heart and in the following cells using the corresponding marker proteins c-kit, keratin 14, calcitonin, and GFAP in mouse tissues: interstitial cells of Cajal of the bladder, medullary thymic epithelial cells of the thymus, parafollicular cells of the thyroid, and Leydig cells of the testis. The expression of ORs in OMP (+) tissues was analyzed using a refined microarray analysis and validated with RT-PCR and real-time PCR. Three ORs (olfr544, olfr558, and olfr1386) were expressed in the OMP (+) cells of the bladder and thyroid as shown using a co-immunostaining method. Together, these results suggest that OMP is involved in the OR-mediated signal transduction cascade with olfactory canonical signaling components between the nervous and endocrine systems. The results further demonstrate that OMP immunohistochemical analysis is a useful tool for identifying expression of ORs, suggesting OMP expression is an indicator of potential OR-mediated chemoreception in non-olfactory systems.
嗅觉受体（OR）相关事件由嗅觉上皮中保守性良好的成分介导，包括嗅觉G蛋白（Golf）、腺苷酸环化酶III（ACIII）和嗅觉标记蛋白（OMP）。最近在非嗅觉组织中观察到OR的表达，它们在这些组织中参与监测细胞外化学信号。大量的OR基因及其序列相似性表明需要找到一种有效且简单的方法来检测非嗅觉OR相关事件。此外，OR在非嗅觉组织中的表达谱和生理功能在很大程度上尚不清楚。为了克服将OR用作靶蛋白的相关局限性，本研究以OMP、Golf和ACIII为靶标，筛选非嗅觉组织中潜在的OR介导的传感系统。在此，我们通过蛋白质印迹法、实时PCR以及单免疫和双免疫分析表明，OR和OR相关蛋白在多种组织中共表达。免疫组织化学分析结果显示，在小鼠心脏中存在OMP（+）细胞，在小鼠组织中使用相应的标记蛋白c-kit、角蛋白14、降钙素和GFAP在以下细胞中也存在OMP（+）细胞：膀胱的Cajal间质细胞、胸腺的髓质胸腺上皮细胞、甲状腺的滤泡旁细胞以及睾丸的Leydig细胞。使用精细的微阵列分析对OMP（+）组织中OR的表达进行了分析，并用RT-PCR和实时PCR进行了验证。使用共免疫染色方法显示，三种OR（olfr544、olfr558和olfr1386）在膀胱和甲状腺的OMP（+）细胞中表达。总之，这些结果表明OMP参与了OR介导的信号转导级联反应，该反应涉及神经和内分泌系统之间的嗅觉经典信号成分。结果进一步证明，OMP免疫组织化学分析是鉴定OR表达的有用工具，表明OMP表达是在非嗅觉系统中潜在的OR介导的化学感受的指标。
