Quality control of the primary cilium proteome

项目摘要 初级纤毛组织信号通路，如视觉，嗅觉和刺猬信号。的 信号受体进入纤毛、进入纤毛和离开纤毛的运动对于正确调节这些信号受体是至关重要的。 途径，但我们的理解的基本机制，通过纤毛信号受体贩运 仍然支离破碎。实验室过去的工作鉴定并表征了BBSome，这是一种蛋白质复合物， 将信号受体从纤毛中运送出来。BBSome与人类健康和疾病的相关性是证据 BBSome功能障碍导致Bardet-Biedl综合征（BBS），这是一种遗传性疾病， 肥胖、视网膜退化、多指畸形和肾脏畸形。 该提案的主要目标是确定BBSome如何选择信号受体进行移除 cilia的。在这一资助期间的重点将是调查泛素在标记膜的作用， 去除纤毛的蛋白质。初步数据表明存在一种纤毛机制， 激活GPCR，使它们泛素化，并将泛素化的GPCR从纤毛中分离出来。我们将描述 分子在这些步骤中的每一个使用信号依赖性GPCR退出的定量测定。的 分子齿轮和杠杆的等级排序，这些齿轮和杠杆在需要退出的蛋白质上附着和读取泛素 纤毛有望揭示一个多步骤的途径，让人想起ESCRT机制， 退化排序最后，将通过单分子成像跟踪退出纤毛的GPCR的命运， 确定内吞作用是否与纤毛出口偶联，或者GPCR是否反而扩散到血浆中 离开纤毛后的膜。 这项研究将为纤毛蛋白质丰度的调节提供新的思路，并打开纤毛蛋白质的表达途径。 一个门的睫状体质量控制的机制调查。

PROJECT SUMMARY Primary cilia organize signaling pathways such as vision, olfaction and Hedgehog signaling. The movements of signaling receptors into, inside and out of cilium are critical for the correct regulation of these pathways, yet our understanding of the basic mechanisms governing signaling receptor trafficking through cilia remains fragmentary. Past work from the lab identified and characterized the BBSome, a protein complex that ferries signaling receptors out of cilia. The relevance of the BBSome to human health and disease is evidence by the fact that BBSome dysfunction causes Bardet-Biedl Syndrome (BBS), a hereditary disease characterized by obesity, retinal degeneration, polydactyly and kidney malformations. The major goal of this proposal is to determine how the BBSome selects signaling receptors for removal from cilia. The emphasis in this funding period will be on investigating the role of ubiquitin in tagging membrane proteins for removal from cilia. Preliminary data indicate the existence of a ciliary machinery that recognizes activated GPCRs, ubiquitinates them and sorts ubiquitinated GPCRs out of cilia. We will characterize the molecules acting at each of these steps using quantitative assays for signal-dependent GPCR exit. The hierarchical ordering of the molecular cogs and levers that affix and read ubiquitin on proteins that need to exit cilia promises to uncover a multi-step pathway reminiscent of the ESCRT machinery responsible for degradative sorting. Finally, the fate of GPCRs that exit cilia will be tracked by single-molecule imaging to determine whether endocytosis is coupled to ciliary exit or whether GPCRs instead diffuse into the plasma membrane after exiting cilia. The proposed studies will cast new light on how the ciliary abundance of proteins is regulated and open the door to a mechanistic investigation of ciliary quality control.