Determinants of GPCR Ciliary Localization and Effects on Signaling

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 它们曾经被认为是退化的，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本病的发病有关 许多人类发育障碍和疾病。然而，纤毛在大多数细胞上的功能尚不清楚。 对纤毛功能障碍和疾病的研究表明，初级纤毛的功能由 定位于纤毛膜的特定信号蛋白。这些研究还表明， 纤毛信号蛋白不能正确定位会导致疾病。然而，纤毛信号很少 蛋白质已被鉴定，调节其纤毛定位的机制尚不清楚。我们 已经发现与人类睫状肌疾病Bardet-Biedl综合征相关的基因缺陷 (Bbs)似乎通过破坏G蛋白偶联运输的机制来影响纤毛功能 纤毛上的受体(GPCRs)。重要的是，这一发现可能代表了 在看似不同的BBS表型的病理生理学基础上，包括肥胖、认知缺陷、 肾囊性疾病和视网膜变性。这项建议的中心假设是：1)睫状物GPCRs 包含介导其纤毛定位的独特序列，2)纤毛定位GPCRs需要 与BBS蛋白的相互作用，以及3)BBS中纤毛受体的错误定位改变信号和导联 对于疾病，本应用的目的是确定gpcr纤毛的分子内决定因素。 定位并使用这些信息来识别新的纤毛信号通路，定义分子间 纤毛定位的决定因素和BBS蛋白调节这一过程的机制(S)， 并确定睫状肌GPCR错位对信号的影响。这些研究将提供有价值的见解 对纤毛GPCRs的贩运进行研究，并将用于预测新的纤毛GPCRs。了解 纤毛定位的决定因素和机制以及纤毛定位缺失对信号的影响 对于阐明这些细胞器的功能并确定它们在发育和发育中的作用至关重要。 疾病。尽管众所周知，人体内几乎每个细胞都有一种重要的感觉和信号 附属物称为初级纤毛，纤毛在大多数细胞上的功能尚不清楚。这些因素的重要性 细胞器突出的事实是，初级纤毛的缺陷与发育有关 紊乱和疾病，包括肥胖、肾脏疾病、失明、神经系统异常、精神疾病 发育迟缓、肝脏疾病和肢体缺陷。从拟议研究中获得的结果将提供 对控制纤毛和纤毛的特定信号蛋白定位的机制的重要见解 这些机制中的中断如何影响信号传递。

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. 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.