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气味信号蛋白转运到哺乳动物嗅觉纤毛中的潜在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。至少20%的病例无法确定化学感觉障碍的病因。最近，我们是第一个证明嗅觉功能障碍作为一类新兴的人类遗传性疾病的临床表现之一，称为纤毛病，涉及纤毛组装和/或蛋白质转运的缺陷。嗅觉感觉神经元（OSNs）纤毛中信号蛋白的富集对于气味检测是必不可少的，然而令人惊讶的是，关于调节蛋白运输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，它们是嗅觉系统中可能参与纤毛运输重要步骤的多蛋白酶的一部分。第一个，CEP 290，是定位于树突状突起的OSN的基体蛋白。我们已经发现，这种蛋白质的亚型突变选择性地抑制G蛋白运输到纤毛，导致嗅觉功能严重受损。第二种是视网膜色素变性GT3调节因子（RPGR）的剪接变体RPGRORF 15，与视网膜中的感觉功能障碍有关。RPGRORF 15定位于OSN的突起和树突，并且该同种型的突变导致小鼠的嗅觉功能障碍。第三个，KIF 17，是一个驱动蛋白马达蛋白，我们已经表明，在异源系统中，需要纤毛富集的嗅觉CNG通道和内源性表达在纤毛的天然OSN。我们已经发现，这些组件中的每一个都与其他已知的纤毛，基体和微管转运蛋白在OSN中，然而，它们在哺乳动物嗅觉系统中的确切作用还不清楚。我们假设，在OSN中，CEP 290，RPGRORF 15和KIF 17是纤毛运输途径的组成部分，其通过在基体/纤毛室中组装多蛋白复合物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，在具体目标1中，我们将定义CEP 290调节嗅觉G蛋白向纤毛运输的机制。在具体目标2中，我们将阐明RPGRORF 15在嗅觉功能和蛋白质运输到纤毛中的功能。在特定目标3中，我们将确定KIF 17在嗅觉信号蛋白定位于纤毛中的作用。我们提出的研究的成功完成将提供新的见解OSN的纤毛贩运和感官知觉的调节机制知之甚少，同时强调，嗅觉功能障碍是一个重要的临床表现的睫状体疾病。在鼻子中，与嗅觉有关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。这项研究的目的是了解嗅觉蛋白如何到达纤毛，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.