Mechanisms of Endocytic Recycling

内吞回收机制

• 批准号: 9322098
• 负责人: VICTOR W HSU
• 金额: $ 9万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9322098
• 关键词: ADP-ribosylation factor 6; Ankyrin Repeat; Binding; Capsid Proteins; Carrier Proteins; Cell division; Cell membrane; Cell surface; Cell-Cell Adhesion; Cells; Clathrin; Complex; Coupled; Critical Pathways; Cryoelectron Microscopy; Crystallography; Data; Disease; Endosomes; Ensure; Environment; Event; GTPase-Activating Proteins; Guanine Nucleotide Exchange Factors; Health; Integrins; Intracellular Transport; Mediating; Membrane; Monomeric GTP-Binding Proteins; Nutrient; PH Domain; Pathway interactions; Phosphatidylinositols; Phosphorylation; Phosphotransferases; Physiological; Play; Process; Proteins; Recruitment Activity; Recycling; Regulation; Resolution; Role; Seminal; Signal Transduction; Sorting - Cell Movement; Structure; Surface; Uncertainty; amphiphysin; cell growth; cell motility; human disease; innovation; insight; novel; particle; protein structure; receptor; uptake

 DESCRIPTION (provided by applicant): Endocytic recycling is critical for many physiologic events, including nutrient uptake, cell signaling, polarity, and cell adhesion and migration. In recent years, we have advanced a fundamental understanding of endocytic recycling by identifying the first coat complex to act in this process. This complex is composed of clathrin coupled to a novel adaptor, known as ACAP1 (Arfgap with Coil-coil, Ankyrin repeat and PH domain 1). We have also identified ARF6 (ADP-Ribosylation Factor 6) to regulate this coat complex, with Grp1 (General receptor for 3-phosphoinositides 1) acting as the guanine nucleotide exchange factor (GEF). More recently, our studies on these factors have uncovered significant new insights, which we propose to pursue in further detail. First, we have recently pursued a cutting-edge approach that combines single-particle cryo-electron microscopy with protein crystallography. This approach has shed unexpected new insight into how ACAP1 bends membrane. Thus, we propose to apply this combined approach to study how ARF6 bends membrane, and also examine how ARF6 cooperates with ACAP1 to impart membrane curvature. Second, we have also uncovered that Akt promotes endocytic recycling through a non-kinase function. Thus, we will examine three possibilities for this novel role: i) acting as a cargo adaptor to promote cargo binding by ACAP1, ii) regulating the GTPase activating protein (GAP) activity of ACAP1, or iii) modulating the ability of ACAP1 to bend membrane. Third, we have also uncovered new insights into the regulation of Grp1, which involves the phosphorylation of a key residue in its PH (Pleckstrin Homology) domain, resulting in Grp1 being targeted to the recycling endosome rather than the plasma membrane. We have also identified additional factors that promote this switch. Thus, we will elucidate how these different targeting mechanisms may be coordinated, and thereby contributing to a better understanding of how ARF GEFs are regulated in complex ways to ensure that a transport pathway is properly initiated. As endocytic recycling underlies many key physiologic events, we anticipate that our studies will not only advance a basic understanding of transport mechanisms, but also shed insights into how endocytic recycling is critical for both health and disease states.

 描述（由适用提供）：内吞回收对于许多生理事件至关重要，包括养分吸收，细胞信号传导，极性以及细胞粘合剂和迁移。近年来，我们通过确定在此过程中采取行动的第一个涂层配合物来提出对内吞回收的基本理解。该复合物由耦合到新型适配器的网格蛋白（称为ACAP1）（带有线圈线圈，Ankyrin Report和pH结构域1）组成。我们还确定了ARF6（ADP-核糖基化因子6）以调节这种涂层复合物，GRP1（3-磷酸固醇的一般受体1）充当鸟嘌呤核丁基交换因子（GEF）。最近，我们对这些因素的研究发现了重大的新见解，我们建议这进一步追求。首先，我们最近采用了一种尖端方法，该方法将单粒子冷冻电子显微镜与蛋白质晶体学结合在一起。这种方法对ACAP1如何弯曲膜产生了出乎意料的新见解。这是我们建议采用这种联合方法来研究ARF6如何弯曲膜，还研究ARF6如何与ACAP1合作以散发膜曲率。其次，我们还发现AKT通过非激酶功能促进内吞回收。这是我们将研究这一新作用的三种可能性：i）充当货物适配器，以促进ACAP1促进货物结合，ii）控制ACAP1或III的GTPase激活蛋白（GAP）活性调节ACAP1弯曲膜的能力。第三，我们还发现了对GRP1的调节的新见解，GRP1的调节涉及其pH（Pleckstrin同源性）结构域中关键居住区的磷酸化，从而导致GRP1靶向回收内体，而不是质膜膜。我们还确定了促进此转换的其他因素。那，我们将阐明这些不同 靶向机制可以协调，从而更好地了解如何以复杂的方式调节ARF GEF，以确保正确启动运输途径。随着内吞回收是许多关键生理事件的基础，我们预计我们的研究不仅会进步对运输机制的基本理解，而且还深入了解了内吞回收对健康和疾病状态至关重要。