Molecular Genesis and Organization of Olfactory Transduction Components and Cilia

描述(申请人提供)：哺乳动物嗅觉系统中气味检测的非凡敏感性和特异性来自高度专业化的细胞和分子成分。存在于嗅觉神经元纤毛中的GPCRs激活了一个转导级联反应，导致电活动和感觉信息传播到大脑。嗅觉受体(OR)基因大家族的发现为个体嗅觉神经元的差异敏感性提供了解释。异源系统中ORs的功能表达为确定气味识别的分子基础提供了机会，并在指导这些蛋白质的有效运输方面取得了一定的进展。然而，我们对天然感觉神经元产生高度专门化的感觉纤毛和定位关键成分的机制知之甚少，包括转导蛋白和气味受体到这些结构。我们最近证明，鞭毛内运输(IFT)系统各部分存在遗传缺陷的个体表现出严重的嗅觉缺陷，这在这种疾病的小鼠模型中得到了概括。这些观察结果为研究体内系统的一般转运过程和了解特殊的完整膜蛋白如何被转移到细胞内的特定位置提供了基础。我们建议定义感觉神经元中用来指导信号转导成分运输的分子装置。嗅觉受体的进化和结构保守使它们独特地服从于对分子分类和亚细胞定位的系统剖析。我们将利用分子和功能方法来可视化和阐明纤毛形成的动力学、OR分布和转导蛋白的定位。这些实验将通过提供关于本土背景下受体贩运的信息来补充那些来自体外分析的实验。这些实验为嗅觉感觉神经元的发育、组织特异性蛋白转移到感觉细胞器的途径以及神经元连接的建立提供了新的见解。蛋白质到特定细胞位置的运输和特殊纤毛的发育对哺乳动物的许多细胞类型都是至关重要的。我们的研究将为人类感觉和纤毛依赖细胞功能疾病的发病机制提供有价值的新信息。

DESCRIPTION (provided by applicant): The remarkable sensitivity and specificity of odorant detection in the mammalian olfactory system derives from highly specialized cellular and molecular components. GPCRs present in the cilia of the olfactory neurons activate a transduction cascade leading to electrical activity and the propagation of sensory information to the brain. The discovery of a large family of olfactory receptor (OR) genes provided an explanation for the differential sensitivity of individual olfactory neurons. Functional expression of ORs in heterologous systems represent an opportunity to define the molecular basis of odorant recognition and has led to modest progress in directing the efficient trafficking of these proteins. However, we know very little about the mechanisms utilized by native sensory neurons to create the highly specialized sensory cilia and localize critical components, including transduction proteins and odorant receptors to these structures. We recently demonstrated that individuals with genetic defects in components of the intraflagellar transport (IFT) system display profound olfactory deficits that are recapitulated in murine models of this disease. These observations provide a foundation for examining the general process of transport in an in vivo system and understanding how specialized integral membrane proteins are moved to specific locations within the cell. We propose to define the molecular apparatus used in sensory neurons to direct the trafficking of signal transduction components. The evolution and structural conservation of olfactory receptors make them uniquely amenable to a systematic dissection of molecular sorting and subcellular localization. We will utilize molecular and functional approaches to visualize and elucidate the dynamics of cilia formation, OR distribution and transduction protein localization. These experiments will complement those derived from in vitro analysis by providing information on receptor trafficking in a native context. These experiments afford new insights into the development of olfactory sensory neurons, pathways for the translocation of tissue-specific proteins to sensory organelles and the establishment of neuronal connectivity. The trafficking of proteins to specific cellular locations and the development of specialized cilia is critical to many cell types in mammals. Our studies should provide valuable new information regarding the pathogenesis of human diseases of sensory perception and cilia-dependent cellular function.