Molecular Genesis and Organization of Olfactory Transduction Components and Cilia

描述（由申请人提供）：哺乳动物嗅觉系统通过新的遗传机制、细胞特化和神经元回路对感觉信息的后续处理实现了显著的灵敏度。嗅觉纤毛是将气味信息转换为信号并传播到大脑的最早阶段。每个嗅觉神经元的十几个长的不动纤毛是感觉细胞暴露于外部环境的唯一部分和气味刺激的来源，它们的存在对于有效的气味检测是必不可少的。嗅觉神经元已经开发出有效但知之甚少的机制来富集纤毛中的嗅觉转导组分（气味受体（OR）、G蛋白（Golf）、腺苷酸环化酶（AC 3）和嗅觉环核苷酸通道）。包含AC 3酶的单一多肽在所有嗅觉神经元中的丰富表达使其特别适合于阐明负责纤毛定位和富集的途径和机制。在这项研究中，我们将使用分子和遗传学的方法来研究一个专门的，但广泛使用的机制和途径是负责AC 3本地化纤毛，这种本地化是至关重要的纤毛动力学和功能的假设。在具体目标1中，我们通过条件性遗传破坏方法靶向AC 3的纤毛定位信号，并确定AC 3重新定位到不同细胞区室中的后果。在具体目标2中，我们将利用robut表达系统来鉴定导致纤毛定位的AC 3易位/富集途径的组分，并检查AC 3在纤毛中的动力学和AC 3定位在纤毛长度调节中的作用。总之，这些实验将扩大我们对一类重要的蛋白质如何在纤毛中富集以及它们选择性定位于这个细胞器的重要性的理解。纤毛基本上存在于所有终末分化的哺乳动物细胞中，对生物体的发育至关重要。腺苷酸环化酶定位的途径和机制将对嗅觉，感觉交流以及广泛的人类健康和理解疾病产生重要影响。AC 3在嗅觉神经元中的丰富性使得它特别适合于详细的研究。AC 3酶在脑和肾的许多神经元纤毛中广泛表达和高度富集，在那里它可能介导神经内分泌/神经递质信号传导，并且它在这些细胞中的亚细胞定位似乎由类似的机制介导。对这一途径的调节会扰乱复杂的行为和代谢过程。此外，AC 3利用的纤毛定位途径可能与其他蛋白质共享，这些蛋白质在纤毛中的存在对细胞功能至关重要。阐明这些途径将提供深入了解对人类健康有广泛影响的细胞过程。

DESCRIPTION (provided by applicant): The mammalian olfactory system achieves remarkable sensitivity through novel genetic mechanisms, cellular specializations, and subsequent processing of sensory information by neuronal circuitry. The earliest steps in the transduction of odorant information into signals that are propagated to the brain occur in olfactory cilia. The dozen long immotile cilia of each olfactory neuron are the only part of the sensory cell exposed to the outside environment and the sources of odorant stimuli and their existence is essential for efficient odor detection. The olfactory neuron has developed efficient but poorly understood mechanisms for enriching the components of olfactory transduction (odorant receptor (OR), G protein (Golf), adenylyl cyclase (AC3) and olfactory cyclic nucleotide channel) in cilia. The abundant expression of the single polypeptide comprising the AC3 enzyme in all olfactory neurons makes it particularly amenable to elucidate the pathways and mechanisms responsible for cilia localization and enrichment. In this grant we will use molecular and genetic approaches to investigate the hypothesis that a specialized but broadly utilized mechanism and pathway is responsible for AC3 localization to cilia and that this localization is critical for cilia dynamics and function. In specific aim 1, we target the cilia localization signa of AC3 in vivo by a conditional genetic disruption approach and determine the consequences of re- localization of AC3 into different cellular compartments. In specific aim 2, we will utilize a robut expression system to identify components of the AC3 translocation/enrichment pathway leading to cilia localization and examine the dynamics of AC3 in cilia and role of AC3 localization in modulation of cilia length. Together, these experiments will expand our understanding of how an important class of proteins are enriched in cilia and the importance of their selective localizatio to this organelle. Cilia are present in essentially all terminally differentiated mammalian cells ad critical for the development of the organism. The pathways and mechanisms underlying adenylyl cyclase localization will have important consequences for olfaction, sensory communication and broadly for human health and understanding disease. The abundance of AC3 in olfactory neurons makes it particularly amenable for detailed studies. The AC3 enzyme is broadly expressed and highly enriched in many neuronal cilia of the brain and kidney where it likely mediates neuroendocrine/neurotransmitter signaling and its subcellular localization in these cells appear to be mediated by similar mechanisms. Modulation of this pathway should perturb complex behaviors and metabolic processes. Additionally, it is likely that the cilia localization pathway utilized by AC3 is shared by other proteins whose presence in cilia is critical for cellular function. Elucidation of these pathways will provide insight into cellular processes that have widespread consequences for human health.