Determinants of GPCR Ciliary Localization and Effects on Signaling

描述（由申请人提供）：初级纤毛是存在于几乎所有哺乳动物细胞上的孤立附属物。虽然初级纤毛曾经被认为是退化的，但它们现在被认为是重要的细胞感觉和信号细胞器。初级纤毛的形成或功能缺陷与许多人类发育障碍和疾病的发病机制有关。然而，纤毛在大多数细胞上的功能尚不清楚。纤毛功能障碍和疾病的研究表明，初级纤毛的功能是由定位于纤毛膜的特异性信号蛋白定义的。这些研究还表明，睫状体信号蛋白不能正确定位可能导致疾病。然而，很少有纤毛信号蛋白已被确定和调节其本地化纤毛的机制仍然未知。我们已经发现，与人类睫状体疾病Bardet-Biedl综合征（BBS）相关的遗传缺陷似乎通过破坏G蛋白偶联受体（GPCR）运输到纤毛上的机制影响纤毛功能。重要的是，这一发现可能代表了看似不同的BBS表型的病理生理学基础的基本机制，包括肥胖、认知缺陷、肾囊肿和视网膜变性。这一建议的主要假设是：1）纤毛GPCR含有介导其定位于纤毛的独特序列，2）GPCR的纤毛定位需要与BBS蛋白相互作用，和3）BBS中纤毛受体的错误定位改变了信号传导并导致疾病。本申请的目的是定义GPCR纤毛定位的分子内决定簇，并使用该信息来鉴定新的GPCR纤毛受体。纤毛信号传导途径，定义了GPCR纤毛定位的分子间决定因素和BBS蛋白调节该过程的机制，并确定了纤毛GPCR错误定位对信号传导的影响。这些研究将提供有价值的洞察睫状GPCR的贩运，并将用于预测新的睫状GPCR。了解纤毛定位的决定因素和机制以及缺乏纤毛定位对信号传导的影响对于阐明这些细胞器的功能并确定它们在发育和疾病中的作用至关重要。 公共卫生部门：虽然我们知道人体内几乎每个细胞都有一个重要的感觉和信号附属物，称为初级纤毛，但大多数细胞上纤毛的功能尚不清楚。这些细胞器的重要性是突出的事实，即在初级纤毛的缺陷已与发育障碍和疾病，包括：肥胖，肾脏疾病，失明，神经系统异常，精神发育迟滞，肝脏疾病和肢体缺陷。从拟议的研究中获得的结果将提供重要的见解，控制特定的信号蛋白的纤毛的本地化的机制，以及这些机制的中断如何影响信号。

DESCRIPTION (provided by applicant): Primary cilia are solitary appendages that are present on nearly all mammalian cells. Although primary cilia were once considered vestigial, they are now recognized as important cellular sensory and signaling organelles. Defects in the formation or function of primary cilia have been implicated in the pathogenesis of many human developmental disorders and diseases. Yet, the functions of cilia on most cells are unknown. Studies of cilia dysfunction and disease have revealed that the functions of primary cilia are defined by the specific signaling proteins that localize to the membrane of the cilium. These studies have also shown that failure of ciliary signaling proteins to properly localize can lead to disease. However, few ciliary signaling proteins have been identified and the mechanisms that regulate their localization to cilia remain unknown. We have discovered that the genetic defects associated with the human ciliary disorder Bardet-Biedl syndrome (BBS) appear to affect cilia function through a mechanism that disrupts trafficking of G protein-coupled receptors (GPCRs) onto the cilium. Importantly, this finding may represent the fundamental mechanism underlying the pathophysiology of the seemingly diverse BBS phenotypes, including obesity, cognitive deficits, renal cystic disease, and retinal degeneration. The central hypotheses of this proposal are; 1) Ciliary GPCRs contain unique sequences that mediate their localization to cilia, 2) Ciliary localization of GPCRs requires interactions with the BBS proteins, and 3) Mislocalization of ciliary receptors in BBS alters signaling and leads to disease The objectives of this application are to define the intramolecular determinants of GPCR ciliary localization and use this information to identify novel ciliary signaling pathways, define the intermolecular determinants of GPCR ciliary localization and the mechanism(s) by which BBS proteins regulate this process, and determine the effects of ciliary GPCR mislocalization on signaling. These studies will lend valuable insight into the trafficking of ciliary GPCRs and will be used to predict novel ciliary GPCRs. Understanding the determinants and mechanisms of ciliary localization and the effects of a lack of ciliary localization on signaling is essential to elucidating the functions of these organelles and determining their roles in development and disease. PUBLIC HEALTH REVELANCE: Although it is known that almost every cell in the human body possesses an important sensory and signaling appendage called a primary cilium, the functions of cilia on most cells are unknown. The importance of these organelles is highlighted by the fact that defects in primary cilia have been associated with developmental disorders and diseases, including; obesity, renal disease, blindness, nervous system abnormalities, mental retardation, liver disease, and limb defects. The results obtained from the proposed studies will provide important insights into the mechanisms that control the localization of specific signaling proteins to cilia and how disruptions in these mechanisms affect signaling.