Olfactory Singaling, Cilia, and Sensory Disorders

描述(申请人提供)：嗅觉信号、纤毛和感觉障碍这项建议的长期目标是阐明气味信号蛋白进入哺乳动物嗅觉纤毛的潜在机制及其在纤毛相关疾病中的变化。嗅觉障碍在普通人群中很常见，仅在美国就有至少250万人受到影响。在至少20%的病例中，无法确定化学感觉障碍的病因。最近，我们是第一批证明嗅觉障碍是一种新兴的人类遗传性疾病的临床表现之一，这种疾病被称为纤毛疾病，涉及纤毛组装和/或蛋白质运输的缺陷。嗅觉感觉神经元(OSN)纤毛中信号蛋白的丰富对于气味检测是必不可少的，然而令人惊讶的是，对调节蛋白质进入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体的一部分，可能参与纤毛运输的重要步骤。第一个是CEP290，是一种定位于OSNs树突状结节的基底体蛋白。我们发现，这种蛋白的亚型突变选择性地抑制G蛋白向纤毛的运输，导致嗅觉功能严重受损。第二，视网膜色素变性GTPase调节子(RPGR)的剪接变异体RPGRORF15，与视网膜的感觉功能障碍有关。RPGRORF15定位于OSNs的节状和树突，该亚型的突变导致小鼠嗅觉功能障碍。第三个是KIF17，是一种激动素马达蛋白，我们已经证明在一个异源系统中，它是嗅觉CNG通道纤毛丰富所必需的，并且在天然OSN的纤毛中内源性表达。我们已经发现，这些成分中的每一个都与OSNs中的其他已知纤毛、基底体和微管运输蛋白相关，然而，它们在哺乳动物嗅觉系统中的确切作用尚不清楚。我们推测，在OSNs中，CEP290、RPGRORF15和KIF17是纤毛运输途径的组成部分，该途径通过在基底体/纤毛室组装多蛋白复合体来协调信号蛋白的运输。这些成分的突变会改变蛋白质的相互作用，导致信号分子的错位和嗅觉功能的丧失。因此，在特定的目标1中，我们将确定CEP290调节嗅觉G蛋白向纤毛运输的机制。在特定的目标2中，我们将阐明RPGRORF15在嗅觉功能和蛋白质转运到纤毛中的作用。在特定的目标3中，我们将确定KIF17在嗅觉信号蛋白定位到纤毛中的作用。我们建议的研究的成功完成将为了解OSN中纤毛运输的机制和感官调节提供新的见解，同时强调嗅觉障碍是睫状神经疾病的重要临床表现。在与公共健康相关的鼻子中，参与嗅觉的神经元有许多纤毛，毛发状的突起进入鼻腔，其中包含所有负责检测气味的蛋白质。这项建议的目标是了解嗅觉蛋白质是如何进入纤毛的，以及为什么这些纤毛蛋白质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.