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.

摘要 Tau聚集体(也称为神经原纤维缠结或NFT)是神经退行性变的标志 统称为tauopathy的疾病。这些疾病是一大类十几种或更多的痴呆症 包括额颞部痴呆、皮克氏病和慢性创伤性脑病。阿尔茨海默氏症 也是一种肌萎缩侧索硬化症，尽管这种疾病最著名的是淀粉样斑块的形成。在这种情况下， 胞外淀粉样斑块诱导细胞内tau聚集。Tau聚集体的形成是 在此之前，tau寡聚被认为是毒性的主要原因，最终诱导细胞 死亡。最近的几篇论文表明，tau寡聚体或聚集体抑制钙释放。 线粒体，然后通过开放线粒体通透性而引发细胞死亡 过渡孔(MPTP)。这种抑制的靶点是Na+/Ca2+交换器NCLX，它定位于 线粒体内膜。目前尚不清楚胞内tau寡聚体和聚集体是如何干扰NCLX的。 因为它们的蜂窝位置不同，所以它们的功能不同。本补充资料的家长拨款数据提供了 潜在的抑制机制。这些数据表明，线粒体内膜上的NCLX是 由外膜上的Mfn2控制。Mfn2是两种线粒体外膜融合蛋白之一， 但它也在线粒体与内质网的连接中发挥作用，内质网是钙交换的场所。 对调节线粒体功能很重要。家长赠款关注的是连接的效果 Mfn2和NCLX之间有一种周围神经病变(Charcot Marie Tooth病CMT2a)，以及 研究CMT2a的可能性是由于过度活跃的钙离子释放到胞浆中所致 NCLX。在这里，我们假设胞浆中的tau寡聚体或tau聚集体具有相反的效果，导致 NCLX功能丧失导致的细胞死亡，这种毒性是通过干扰Mfn2功能介导的。这个 线粒体中产生的钙超载可以通过打开MPTP而导致坏死。在此方案中，Mfn2 将在胞浆和NCLX之间提供一座桥梁，胞质是tau聚集体定位的地方，NCLX在 内膜。因此，这一补充的目的是确定tau低聚物或 聚集是由于线粒体中的钙超载，如果这种超载是由干扰Mfn2引起的 及其下游效应器NCLX。Tau寡聚体和聚集体对Mfn2/NCLX介导的钙离子的影响 释放和细胞死亡将首先使用现有的培养细胞模型进行研究(HEK293 传感器细胞)，然后与越来越复杂的系统(分化的神经元和斑马鱼)在 准备提交带有鼠标模型的R01。这一新的tau诱导途径的发现 毒性也为药物治疗提供了新的靶点(Mfn2和NCLX)。对几个项目进行了试点试验 候选分子将作为本补充的一部分进行，为大规模筛查做准备 随着这个项目的进展，还有其他的分子。