Olfactory Singaling, Cilia, and Sensory Disorders

描述（由申请人提供）：嗅觉信号，纤毛和感觉障碍本提案的长期目标是阐明嗅觉信号蛋白进入哺乳动物嗅纤毛的运输机制及其在纤毛相关疾病中的改变。嗅觉功能障碍在普通人群中很常见，仅在美国就影响了至少250万人。在至少20%的病例中，化学感觉障碍的病因无法确定。最近，我们率先证明嗅觉功能障碍是一种新兴的人类遗传疾病的临床表现，称为纤毛病，它涉及纤毛组装和/或蛋白质运输的缺陷。嗅觉感觉神经元（OSNs）纤毛中信号蛋白的富集对气味检测至关重要，然而令人惊讶的是，关于调节蛋白质转运到嗅觉纤毛的机制知之甚少。我们最近发现了3种新的调节蛋白，它们是嗅觉系统中多蛋白复合物的一部分，可能参与了纤毛运输的重要步骤。第一种是CEP290，是一种定位于osn树突结节的基础体蛋白。我们发现该蛋白的亚形态突变选择性地抑制g蛋白向纤毛的运输，导致嗅觉功能严重受损。第二种是色素性视网膜炎GTPase调节剂（RPGR）的剪接变体rpgorf15，与视网膜感觉功能障碍有关。RPGRORF15定位于osn的结节和树突上，该异构体的突变会导致小鼠嗅觉功能障碍。第三种，KIF17，是一种运动蛋白，我们已经证明，在异源系统中，它是嗅觉CNG通道纤毛富集所必需的，并且在天然osn的纤毛中内源性表达。我们发现这些成分都与其他已知的纤毛、基底体和微管转运蛋白有关，然而，它们在哺乳动物嗅觉系统中的确切作用尚不清楚。我们假设，在nos中，CEP290、RPGRORF15和KIF17是纤毛运输途径的组成部分，该途径通过基底体/纤毛室中多蛋白复合物的组装来协调信号蛋白的运输。这些成分的突变改变了蛋白质的相互作用，导致信号分子的错误定位和嗅觉功能的丧失。因此，在Specific Aim 1中，我们将定义CEP290调节嗅觉g蛋白向纤毛运输的机制。在Specific Aim 2中，我们将阐明RPGRORF15在嗅觉功能和蛋白质运输到纤毛中的功能。在特异性目标3中，我们将确定KIF17在嗅觉信号蛋白定位到纤毛中的作用。我们所提出的研究的成功完成将为尚不为人所知的纤毛转运机制和感觉知觉的调节提供新的见解，同时强调嗅觉功能障碍是纤毛疾病的重要临床表现。在鼻子中，与嗅觉有关的神经元有许多纤毛，这些毛发状的突起延伸到鼻腔，其中包含了所有负责探测气味的蛋白质。这项提议的目的是了解嗅觉蛋白是如何到达纤毛的，以及为什么这些纤毛蛋白的基因突变会导致嗅觉丧失。

DESCRIPTION (provided by applicant): Olfactory Signaling, Cilia, and Sensory Disorders The long-range goal of this proposal is to elucidate the mechanisms underlying the transport of odorant signaling proteins into mammalian olfactory cilia and their alterations in cilia-related disorders. Olfactory dysfunction in the general population is frequent, affecting at least 2.5 million people in the U.S. alone. In at least 20% of the cases the etiology of the chemosensory disturbance cannot be identified. Recently, we were one of the first to demonstrate olfactory dysfunction as a clinical manifestation of an emerging class of human genetic disorders, termed ciliopathies, which involve defects in ciliary assembly and/or protein transport. The enrichment of signaling proteins in the cilia of olfactory sensory neurons (OSNs) is essential for odor detection, however surprisingly little is known regarding the mechanisms regulating protein trafficking into olfactory cilia. We have recently identified 3 novel regulatory proteins as part of a multiprotein complexe in the olfactory system that likely participates in important steps of ciliary transport. The first, CEP290, is a basal body protein localized to dendritic knobs of OSNs. We have discovered that hypomorphic mutations in this protein selectively inhibit G-protein trafficking to cilia resulting in severe impairment of olfactory function. The second, a splice variant of Retinitis Pigmentosa GTPase Regulator (RPGR), RPGRORF15, is associated with sensory dysfunction in the retina. RPGRORF15 is localized to the knobs and dendrites of OSNs and a mutation of this isoform results in olfactory dysfunction in mice. The third, KIF17, is a kinesin motor protein that we have shown, in a heterologous system, to be required for ciliary enrichment of the olfactory CNG channel and is endogenously expressed in the cilia of native OSNs. We have found that each of these components is associated with other known ciliary, basal body, and microtubule transport proteins in OSNs however, their precise role in the mammalian olfactory system is unclear. We hypothesize that, in OSNs, CEP290, RPGRORF15, and KIF17 are components of the ciliary transport pathway which orchestrate the trafficking of signaling proteins by assembly of multiprotein complexes in the basal body/cilia compartment. Mutations in these components alter protein interactions leading to the mislocalization of signaling molecules and a loss of olfactory function. Therefore, in Specific Aim 1 we will define the mechanism by which CEP290 regulates trafficking of olfactory G-proteins to cilia. In Specific Aim 2, we will elucidate the function of RPGRORF15 in olfactory function and protein trafficking to cilia. In Specific Aim 3, we will determine the role of KIF17 in olfactory signaling protein localization to cilia. Successful completion of our proposed studies will afford new insights into the poorly understood mechanisms of ciliary trafficking in OSNs and the regulation of sensory perception while emphasizing that olfactory dysfunction represents an important clinical manifestation of ciliary disease. PUBLIC HEALTH RELEVANCE In the nose, neurons involved in smell have many cilia, hair-like projections into the nasal cavity, which contain all of the proteins responsible for detecting odors. The goal of this proposal is to understand how olfactory proteins get to the cilia and why genetic mutations in proteins of these cilia result in the loss of smell.