Understanding the influence of FTDP-17 mutation on human tau circular RNA formation and function to develop treatment options

了解 FTDP-17 突变对人类 tau 环状 RNA 形成和功能的影响，以制定治疗方案

• 批准号: 9975470
• 负责人: Stefan Stamm
• 金额: $ 42.08万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2023-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9975470
• 关键词: Affect; Affinity Chromatography; Age-Years; Alzheimer' s Disease; Amino Acid Sequence; Amino Acids; Back; Behavior; Behavioral; Binding; Brain; Budgets; Cells; Cessation of life; Chromosome 17; Complex; Data; Drug Targeting; Exons; FTD with parkinsonism; Fishes; Frontotemporal Dementia; Genes; Genetic Diseases; Guanosine; Human; Impaired cognition; Initiator Codon; Internal Ribosome Entry Site; Investigation; K-18 conjugate; Knowledge; Link; Location; MAPT gene; Maps; Mass Spectrum Analysis; Mediating; Microtubules; Modeling; Molecular; Mutation; Nature; Neurofibrillary Tangles; Neurons; Nucleotides; Oligonucleotides; Open Reading Frames; Parkinsonian Disorders; Pathology; Peptides; Personality; Physiological; Polymers; Proteins; RNA; RNA Splicing; Reading Frames; Reporter Genes; Reporting; Sampling; Seeds; Site; Structure; Subgroup; Symptoms; Syndrome; System; Tauopathies; Temporal Lobe; Terminator Codon; Testing; Textbooks; Transfection; Translating; Translations; Woman; Zebrafish; circular RNA; drug testing; experimental study; frontal lobe; induced pluripotent stem cell; innovation; knock-down; mRNA Precursor; men; molecular modeling; mutant; neurofibrillary tangle formation; neuron loss; overexpression; polypeptide; prevent; tau Proteins; tau aggregation; tau mutation

53 currently known mutations in the human microtubule associated protein tau gene (MAPT) cause frontotemporal dementia, characterized by behavioral disturbances, cognitive impairment and parkinsonism. These mutations have been described as frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). The dominant mutations affect men and woman equally and have an average onset of 49 years of age. We recently reported that human MAPT generates two human-specific circular RNAs, caused by back-splicing of exon 12 to either exon 7 or 10. Intriguingly, 46 of the 53 known FTDP-17 mutations are located in these circular RNAs. The FTDP-17 mutations V337M and K317M introduce a start codon in tau 12->10 circRNA, which lacks a start codon in all reading frames. Highly unexpectedly, transfection experiments with reporter genes showed that the circular RNAs are translated in HEK293 cells. This suggests that the V337M and K317M mutations act by generating a protein from the tau 12->10 circular RNA. The 12->10 circRNA contains 288 nt and no stop codon. Since 288 nt/3 = 96 amino acids, the presence of V337M and K317M leads to a rolling circle translation creating tau polymers. We observed one to three rounds of translation, i.e. a protein predicted of 96-288 amino acids in both mutants. The tau circ12->7 RNA is weakly expressed but has its own start codon and again we observe translation using reporter gene systems. We postulate that other FTDP-17 mutations influence translatability, stability and/or location of the tau circ12->7 RNA and its protein products. We will test the hypothesis that FTDP-17 mutations act through tau circular RNAs by generating peptides that promote the formation of neurofibrillary tangles (NFT) in two specific aims. First, we will characterize the influence of FTDP-17 mutation on translatability of the tau 12->10 and 12->7 circRNAs, investigate the translational initiation and possible contributions to NFT formation. In the second Aim, we will Investigate the influence of tau circular RNAs harboring FTDP-17 mutations on neurons and zebrafish and explore treatment options. These experiments are highly innovative as they are one of the first demonstration of a translation of a natural circular RNA in a rolling circle mechanism. The translation is completely unexpected, as the circular RNAs lack a trimethyl guanosine cap and a known ribosomal entry site and thus according to current `textbook knowledge, should not be translated. The findings are significant, as they could provide a new model for the molecular mechanism that generates tau aggregates in FTDP-17. Although the FTDP-17 mutations are rare, they can be considered `experiments of nature', which will help understand the more frequent tau pathology in Alzheimer's disease.

53目前已知的人微管相关蛋白tau基因（MAPT）突变导致额颞叶痴呆，其特征在于行为障碍、认知障碍和帕金森综合征。这些突变被描述为与17号染色体（FTDP-17）相关的额颞叶痴呆和帕金森综合征。显性突变同样影响男性和女性，平均发病年龄为49岁。我们最近报道，人类MAPT产生两个人类特异性环状RNA，由外显子12反向剪接到外显子7或10引起。 有趣的是，53个已知的FTDP-17突变中有46个位于这些环状RNA中。FTDP-17突变V337 M和K317 M在tau 12->10 circRNA中引入起始密码子，其在所有阅读框中缺乏起始密码子。非常出乎意料的是，用报告基因进行的转染实验显示，环状RNA在HEK 293细胞中被翻译。这表明V337 M和K317 M突变通过从tau 12->10环状RNA产生蛋白质起作用。12->10 circRNA含有288个核苷酸，无终止密码子。由于288 nt/3 = 96个氨基酸，V337 M和K317 M的存在导致滚环翻译产生tau聚合物。我们观察到一到三轮翻译，即在两种突变体中预测的96-288个氨基酸的蛋白质。tau circ 12->7 RNA弱表达，但具有其自身的起始密码子，并且我们再次使用报告基因系统观察到翻译。我们假设其他FTDP-17突变影响Tau circ 12->7 RNA及其蛋白产物的可翻译性、稳定性和/或位置。我们将测试FTDP-17突变通过tau环状RNA产生促进神经元缠结（NFT）形成的肽的假设。一是 表征FTDP-17突变对tau 12->10和12->7 circRNA的可翻译性的影响， 研究翻译起始和NFT形成的可能贡献。在第二个目标中，我们将 研究携带FTDP-17突变的tau环状RNA对神经元和斑马鱼的影响， 探索治疗方案。这些实验是高度创新的，因为它们是在滚环机制中翻译天然环状RNA的第一个证明之一。翻译是完全出乎意料的，因为环状RNA缺乏三甲基鸟苷帽和已知的核糖体进入位点，因此根据当前的“教科书 知识不应该被翻译。这些发现是重要的，因为它们可以为人类提供一个新的模型。 在FTDP-17中产生tau聚集体的分子机制。虽然FTDP-17突变很罕见， 它们可以被认为是“自然实验”，这将有助于理解在人类中更常见的tau病理学。 老年痴呆症