Regulation of Nutrient Homeostasis by COMMD proteins

COMMD 蛋白对营养稳态的调节

• 批准号: 10394205
• 负责人: DANIEL D BILLADEAU
• 金额: $ 43.93万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10394205
• 关键词: AGFG1 gene; Actins; Affect; Alleles; Animals; Attention; Back; Binding; Biochemical; Cardiac; Cell Line; Cell membrane; Cell physiology; Cell surface; Complex; Copper; Data; Defect; Development; Elements; Endosomes; Excretory function; Family; Funding; GLUT-2 protein; Genes; Goals; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; Homeostasis; Insulin; Intestines; LDL Cholesterol Lipoproteins; Laboratories; Lipids; Liver; Location; Mediating; Membrane Proteins; Molecular; Movement; Mutation; Nutrient; Pathway interactions; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Physiological; Plasma; Play; Process; Proteins; Proteomics; Publishing; Recruitment Activity; Recycling; Regulation; Reporting; System; Testing; Wilson disease protein; Work; base; glucose tolerance; in vivo; member; mouse model; myotubularin; notch protein; nutrition; receptor; recruit; response; sorting nexins; trafficking

Plasma membrane proteins, including receptors and nutrient transporters, undergo internalization into the endosomal compartment, from where these proteins are recycled back to the plasma membrane. This endosomal recycling process is essential to cellular homeostasis. Our laboratories have discovered two interrelated complexes that play key roles in endosomal recycling known as CCC and retriever. Both of these assemblies work in concert with WASH, an endosomally-localized actin nucleating pentameric complex. Significantly, perturbations of these systems have far-reaching consequences, including developmental anomalies, altered copper and lipid handling, and defective glucose tolerance. These physiologic alterations can be traced to faulty trafficking of key receptors and transporters including Notch, ATP7A/ATP7B, LDLR and GLUT2. At its core, the CCC complex contains COMMD proteins, in association with two coiled-coil proteins, CCDC22 and CCDC93. We recently demonstrated that CCC regulates the WASH complex by limiting the amount of endosomal PI(3)P through an interaction with the PI(3)P phosphatase MTMR2. We also uncovered that the CCC complex recruits a cargo recognition complex, termed retriever, whose function is to identify proteins that need to be recycled. While we made great progress in dissecting the mechanistic underpinnings of these systems, our understanding is still rudimentary. The overall goal of this project is to provide a deep mechanistic picture of CCC-mediated regulation of WASH and retriever, focusing our attention on endosomal recycling of nutrient regulators. Based on new emerging data, this proposal will test the hypothesis that the CCC complex coordinates both PI(3)P levels and Rab21 activation to promote retriever-mediated recycling of surface proteins. This project will focus on the following specific aims: (1) Determine the mechanism by which CCC regulates MTMR actions on endosomes. In this aim we will examine how the CCC complex coordinates MTMR actions, particularly by MTMR5, together with activation of Rab21 and retriever recruitment. (2) Define the mechanism by which PI(3)P regulates the recruitment and activity of the WASH complex. In this aim, we will define the mechanisms by which PI(3)P-binding domains in FAM21 and WASH regulate the endosomal recruitment and activity of the WASH complex, and how these activities ultimately impact endosomal trafficking. (3) Examine retriever-dependent regulation of cargo proteins in vivo. In this aim we will utilize newly generated mouse models of retriever deficiency (conditional Vps35l, Vps26c alleles) to examine the contribution of this system to ATP7B and LDLR trafficking in the liver. Furthermore, we will utilize proteomics to define the breadth of plasma membrane proteins regulated by retriever, CCC, and WASH in the mammalian liver. Altogether, this project will elucidate important principles that govern the trafficking of a myriad of cargoes that traverse the endosomal system. Deregulation of these pathways have a broad impact on normal organismal/cellular physiology, thus its scientific impact will have far reaching implications for several biomedical fields.

质膜蛋白（包括受体和营养转运蛋白）将内部化到内体室中，从那里这些蛋白回收回到质膜。这种内体回收过程对于细胞稳态至关重要。我们的实验室发现了两个相互关联的复合物，这些复合物在被称为CCC和猎犬的内体回收中起关键作用。这两个组件都与WASH（一种内体积化的肌动蛋白成核配合物）一起合作。值得注意的是，这些系统的扰动具有深远的后果，包括发育异常，铜和脂质处理改变以及葡萄糖耐受性有缺陷。这些生理变化可以追溯到关键受体和转运蛋白的运输错误，包括Notch，ATP7A/ATP7B，LDLR和GLUT2。 CCC复合物在其核心上含有COMMD蛋白，与两个盘绕蛋白CCDC22和CCDC93相关。我们最近证明，CCC通过与PI（3）P磷酸酶MTMR2的相互作用来限制内体PI（3）P的量来调节洗涤复合物。我们还发现，CCC复合物募集了一种称为猎犬的货物识别配合物，其功能是识别需要回收的蛋白质。尽管我们在剖析这些系统的机械基础方面取得了重大进展，但我们的理解仍然是基本的。该项目的总体目标是提供CCC介导的洗涤和猎犬调节的深刻机械图，将我们的注意力集中在营养调节剂的内体回收上。基于新的新兴数据，该提案将检验以下假设：CCC复合物均协调PI（3）P水平和RAB21激活，以促进回猎犬介导的表面蛋白的回收。该项目将重点关注以下特定目的：（1）确定CCC调节MTMR对内体的机制。在此目标中，我们将研究CCC复合物如何协调MTMR的作用，尤其是MTMR5，以及RAB21和RETRIEVER募集的激活。 （2）定义PI（3）p调节Wash复合物的募集和活性的机制。在此目标中，我们将定义FAM21中的PI（3）P结合域并WASH调节WASH综合体的内体募集和活动的机制，以及这些活动最终如何影响内体运输。 （3）检查体内货物蛋白的检索依赖性调节。在此目的中，我们将利用新近生成的猎犬缺陷的小鼠模型（条件VPS35L，VPS26C等位基因）来检查该系统对肝脏中ATP7B和LDLR运输的贡献。此外，我们将利用蛋白质组学来定义哺乳动物肝脏调节的质膜蛋白的广度。总的来说，该项目将阐明重要的原则，这些原则管理着遍及内体系统的无数货物的贩运。对这些途径的放松管制对正常的有机体/细胞生理具有广泛的影响，因此其科学影响将对几个生物医学领域具有很大的影响。