Role of Rab27b in synucleinopathies

Rab27b 在突触核蛋白病中的作用

• 批准号: 10204274
• 负责人: Talene Alene Yacoubian
• 金额: $ 43.07万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10204274
• 关键词: AGFG1 gene; Affect; Age; Alzheimer' s Disease; Autophagocytosis; Autophagosome; Autopsy; Axonal Transport; Biological Assay; Brain; Cell Line; Cell membrane; Cells; Data; Disease; Disease Progression; Doxycycline; Dystonia; Endocytosis; Exposure to; Functional disorder; Goals; Human; Image; Impaired cognition; Impairment; In Vitro; Knock-out; Lead; Lewy Bodies; Lewy Body Dementia; Link; Mediating; Microfluidic Microchips; Modeling; Monomeric GTP-Binding Proteins; Motor; Nerve Degeneration; Neurodegenerative Disorders; Neuroglia; Neurons; Parkinson Disease; Parkinson' s Dementia; Parkinsonian Disorders; Pathogenesis; Pathologic; Pathway interactions; Play; Protein Isoforms; Protein Secretion; Proteins; Risk Factors; Role; Structure; Syndrome; Testing; Therapeutic; Toxic effect; Variant; alpha synuclein; base; cell type; cognitive disability; cognitive function; extracellular; improved; in vivo; knock-down; motor behavior; neuron loss; new therapeutic target; paracrine; prevent; protein degradation; protein misfolding cyclic amplification; protein transport; synucleinopathy; therapeutic target; trafficking; transmission process; uptake

The goal of this project is to examine the role of Rab27 in synucleinopathies, including Parkinson's disease and Dementia with Lewy Bodies. Misfolding and cell-to-cell propagation of αsyn are hypothesized to play a major role in the pathogenesis of Parkinson's Disease and Dementia with Lewy Bodies. Key steps implicated in α-syn spread include active release, uptake, and misfolding, yet the key mechanisms that regulate the spread of α-syn are poorly understood. Rab proteins are small GTPase proteins that interact with Rab effector proteins to control protein trafficking and degradation and have been implicated in αsyn pathogenesis. We recently identified a potential role for Rab27b in synucleinopathies. Rab27b, which is highly enriched in neurons, plays a role in protein secretion in multiple cell types including neurons, but has also been linked to autophagy and endocytosis. Alterations in Rab27b are associated with Alzheimer's disease, Dementia with Lewy Bodies, and X-linked dystonia parkinsonism syndrome. We recently found a dramatic increase in Rab27b in human PD postmortem brains and in an inducible αsyn cell line (isyn). Rab 27b knockdown (KD) in isyn cells reduces αsyn release and impairs autophagic clearance, consequently promoting αsyn toxicity. In contrast, Rab27a/b double knockout (DKO) leads to a dramatic reduction in αsyn aggregation in neurons exposed to extracellular αsyn protofibrils (PFFs) in vitro and in vivo, most likely due to reduced uptake. Based on these data, we hypothesize that Rab27b plays two independent roles that affect αsyn handling: 1) it regulates entry of extracellular αsyn via endocytosis; and 2) it promotes clearance of intracellular αsyn via secretion and autophagy. In disease, fibrillar αsyn co-opts cell entry pathways via Rab27b and thus indirectly disrupts Rab27b's clearance of intracellular αsyn. We propose that differential effects of Rab27b on autophagy, secretion, and uptake are mediated by different Rab27 effector pathways. In Aim 1, we will test the ability of Rab27b to mediate αsyn entry into neurons and the relevant Rab27 effectors that mediate uptake. In Aim 2, we will focus on the impact of Rab27b on clearance of intracellular α-syn by active secretion and autophagy, determine the relevant Rab27 effectors that mediate these effects on autophagy and secretion, and test whether fibrillar αsyn induces a redistribution of Rab27b away from endolysosomal structures to interfere with clearance activities. In Aim 3, we will test the consequences of Rab27b and relevant effectors on cognitive function, αsyn inclusion formation, and neuronal loss in the in vivo α-syn PFF model. Further understanding of the mechanisms by which Rab27b affects αsyn trafficking is critical to understand its role in disease and its therapeutic potential.

该项目的目的是检查RAB27在棘突病中的作用，包括帕金森氏病和 痴呆症有刘易的身体。假设αSyn的错误折叠和细胞间传播可以发挥作用 在帕金森氏病和痴呆症的发病机理中的作用。与α-Syn有关的关键步骤 传播包括主动释放，摄取和错误折叠，但是调节α-Syn扩散的关键机制 知之甚少。 Rab蛋白是与Rab效应蛋白相互作用以控制的小GTPase蛋白 蛋白质运输和降解已在αSyn发病机理中暗示。我们最近确定了 RAB27B在突触核苷中的潜在作用。在神经元中高度丰富的Rab27b在 包括神经元在内的多种细胞类型中的蛋白质分泌，但也与自噬和内吞作用有关。 Rab27b的改变与阿尔茨海默氏病，痴呆症与Lewy身体和X连锁有关 肌张力障碍帕金森氏症综合症。我们最近发现人类PD术后Rab27b的急剧增加 大脑和诱导的αSyn细胞系（ISON）。 ISYN细胞中的Rab 27b敲低（KD）降低了αSyn释放和 损害自噬清除率，从而促进αSyn毒性。相比之下，Rab27a/b双淘汰赛 （dko）导致暴露于细胞外αSyn原纤维的神经元中αSyn聚集的急剧降低 （PFF）体外和体内，很可能是由于摄取减少所致。基于这些数据，我们假设RAB27B 扮演两个影响αSyn处理的独立角色：1）它通过内吞作用调节细胞外αSyn的进入； 2）它通过分泌和自噬促进了细胞内αSyn的清除。在疾病中，纤维αSyn共同OPT 通过RAB27B的细胞进入途径，因此间接破坏了Rab27b的细胞内αSyn的清除。我们建议Rab27b对自噬，分泌和摄取的差异作用是由不同的RAB27效应器途径介导的。在AIM 1中，我们将测试RAB27B介导αSyn进入神经元的能力以及培养基吸收的相关RAB27效应。在AIM 2中，我们将重点介绍RAB27B对通过主动分泌和自噬清除细胞内α-Syn的影响，确定相关的RAB27效果，这些效应介导这些对这些影响的影响 自噬和分泌，并测试Fibrillarα-Syn是否诱导Rab27b从内溶性结构中重新分布，从而干扰清除活性。在AIM 3中，我们将测试RAB27B的后果以及对体内α-Syn PFF模型中认知功能，α-Syn包含形成和神经元丧失的相关作用。对RAB27B影响α-Syn运输的机制的进一步理解对于了解其在疾病中的作用及其治疗潜力至关重要。