Mitochondrial calcium overload and necrosis in tauopathies caused by inhibition of Mfn2 and NCLX

抑制 Mfn2 和 NCLX 引起的 tau蛋白病中线粒体钙超载和坏死

• 批准号: 10714837
• 负责人: Carla M Koehler
• 金额: $ 39万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10714837
• 关键词: Alzheimer' s Disease; Calcium; Cell Death; Cell Death Induction; Cell model; Cells; Charcot-Marie-Tooth Disease; Chimeric Proteins; Complex; Cultured Cells; Cytosol; Data; Dementia; Disease; Endoplasmic Reticulum; Frontotemporal Dementia; Goals; Growth; Inner mitochondrial membrane; Location; Mediating; Membrane; Mitochondria; Necrosis; Neurodegenerative Disorders; Neurofibrillary Tangles; Neuronal Differentiation; Neurons; Outer Mitochondrial Membrane; Paper; Pathway interactions; Peripheral Nervous System Diseases; Pick Disease of the Brain; Preparation; Process; Proteins; Role; Senile Plaques; System; Tauopathies; Toxic effect; Zebrafish; amyloid formation; chronic traumatic encephalopathy; experimental study; extracellular; mitochondrial permeability transition pore; mouse model; new therapeutic target; novel; parent grant; protein aggregation; sensor; targeted treatment; tau Proteins; tau aggregation

Abstract Tau aggregates (also known as neurofibrillary tangles or NFTs) are hallmarks of the neurodegenerative diseases collectively known as tauopathies. These diseases are a broad class of a dozen or more dementias that include the frontotemporal dementias, Pick’s disease, and chronic traumatic encephalopathy. Alzheimer’s is also a tauopathy, even though this disease is best known for the formation of amyloid plaques. In this case, the extracellular amyloid plaques induce intracellular tau aggregation. The formation of tau aggregates is preceded by tau oligomerization, which is considered the primary cause of toxicity, ultimately inducing cell death. Several recent papers suggest that tau oligomers or aggregates inhibit calcium release from mitochondria, which then triggers cell death through necrosis by opening of the mitochondrial permeability transition pore (MPTP). The target of this inhibition is the Na+/Ca2+ exchanger NCLX, which is localized to the mitochondrial inner membrane. It is unclear how cytosolic tau oligomers and aggregates interfere with NCLX function because of their different cellular locations. Data from the parent grant of this supplement provides a potential mechanism for inhibition. These data show that NCLX on the mitochondrial inner membrane is controlled by Mfn2 on the outer membrane. Mfn2 is one of two mitochondrial outer membrane fusion proteins, but it also plays a role in tethering of mitochondria to the endoplasmic reticulum where calcium exchange is important for regulating mitochondrial functions. The parent grant focuses on the effects that the connection between Mfn2 and NCLX have on a peripheral neuropathy (the Charcot Marie Tooth disease CMT2A), and investigates the possibility that CMT2A is caused by excessive Ca2+ release into the cytosol through overactive NCLX. Here, we hypothesize that cytosolic tau oligomers or tau aggregates have the opposite effect, causing cell death by loss of NCLX function, and that this toxicity is mediated by interference with Mfn2 function. The resulting Ca2+ overload in mitochondria can then cause necrosis by opening MPTP. In this scenario, Mfn2 would provide a bridge between the cytosol, which is where tau aggregates are localized, and NCLX on the inner membrane. The aim of this supplement is therefore to determine whether the toxicity of tau oligomers or aggregates is due to calcium overload in mitochondria and if this overload is caused by interference with Mfn2 and its downstream effector NCLX. The effects of tau oligomers and aggregates on Mfn2/NCLX-mediated Ca2+ release and cell death will first be investigated using an existing cultured cell model for tauopathies (HEK293 sensor cells) and then with increasingly more complex systems (differentiated neurons and Zebrafish) in preparation for submitting an R01 with mouse models. The discovery of this novel pathway for tau-induced toxicity also provides new targets for drug treatment (Mfn2 and NCLX). Pilot experiments with several candidate molecules will be conducted as part of this supplement in preparation for large scale screens for other molecules as this project progresses.

抽象的 tau聚集体（也称为神经纤维缠结或NFTS）是神经退行性的标志 疾病统称为auopathies。这些疾病是十几个或更多痴呆症的广泛类 其中包括额叶痴呆症，Pick的疾病和慢性创伤性脑病。阿尔茨海默氏症 尽管这种疾病以淀粉样蛋白斑的形成而闻名，但也是一种tauopathy。在这种情况下， 细胞外淀粉样斑块诱导细胞内TAU聚集。 tau聚集体的形成是 在被认为是毒性的主要原因的tau寡聚之前，最终诱导了细胞 死亡。最近的几篇论文表明，tau低聚物或聚集体抑制了钙的释放 线粒体，然后通过打开线粒体渗透性触发细胞死亡 过渡孔（MPTP）。这种抑制的目标是Na+/Ca2+交换器NCLX，该NCLX位于 线粒体内膜。目前尚不清楚胞质tau低聚物如何和汇总干扰NCLX 由于其不同的细胞位置而起作用。父母授予此补充的数据提供了 抑制的潜在机制。这些数据表明，线粒体内膜上的NCLX是 由MFN2在外膜上控制。 MFN2是两个线粒体外膜融合蛋白之一， 但这也在将钙交换的线粒体绑定到内质网中起作用 对于控制线粒体功能很重要。父母赠款专注于连接的影响 在MFN2和NCLX之间具有外周神经病（Charcot Marie牙齿疾病CMT2A），并且 研究CMT2A是由于过度活跃到细胞质中的过量Ca2+引起的可能性 NCLX。在这里，我们假设胞质Tau低聚物或Tau聚集体具有相反的效果，从而导致 细胞死亡通过NCLX功能的丧失而死亡，并且这种毒性是通过干扰MFN2功能介导的。这 线粒体中所得的Ca2+过载可以通过打开MPTP引起坏死。在这种情况下，MFN2 将在tau聚集物所在的地方提供一座桥，而NCLX在 内膜。因此，该补充的目的是确定tau低聚物或 聚集体是由于线粒体中的钙过载，如果此超负荷是由对MFN2的干扰引起的 及其下游效应子NCLX。 Tau低聚物和聚集体对MFN2/NCLX介导的Ca2+的影响 释放和细胞死亡将首先使用现有培养的细胞模型研究（HEK293） 传感器单元），然后在越来越复杂的系统（分化神经元和斑马鱼）中 准备使用鼠标模型提交R01。发现这一新颖的tau引起的途径 毒性还为药物治疗（MFN2和NCLX）提供了新的靶标。多个试验实验 候选分子将作为该补充剂的一部分进行，以准备大规模筛选 随着该项目的进展，其他分子。