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.

目前已知的人类微管相关蛋白 tau 基因 (MAPT) 中的 53 种突变会导致额颞叶痴呆，其特征是行为障碍、认知障碍和帕金森症。这些突变被描述为与 17 号染色体相关的额颞叶痴呆和帕金森病 (FTDP-17)。显性突变对男性和女性的影响相同，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的环状 RNA，这是由外显子 12 反向剪接到外显子 7 或 10 引起的。 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 V337M 和 K317M 在 tau 12->10 circRNA 中引入起始密码子，该环状RNA在所有阅读框中都缺乏起始密码子。非常出乎意料的是，报告基因的转染实验表明环状RNA在HEK293细胞中被翻译。这表明 V337M 和 K317M 突变通过从 tau 12->10 环状 RNA 生成蛋白质来发挥作用。 12->10 circRNA 包含 288 nt，无终止密码子。由于 288 nt/3 = 96 个氨基酸，V337M 和 K317M 的存在导致滚环平移，产生 tau 聚合物。我们观察到一到三轮翻译，即两个突变体中预测的蛋白质有 96-288 个氨基酸。 tau circ12->7 RNA 表达较弱，但有自己的起始密码子，我们再次使用报告基因系统观察翻译。我们假设其他 FTDP-17 突变影响 tau circ12->7 RNA 及其蛋白质产物的可翻译性、稳定性和/或位置。我们将测试以下假设：FTDP-17 突变通过 tau 环状 RNA 产生肽，促进神经原纤维缠结 (NFT) 的形成，达到两个特定目标。首先，我们将 表征 FTDP-17 突变对 tau 12->10 和 12->7 circRNA 可翻译性的影响， 研究翻译起始和对 NFT 形成的可能贡献。在第二个目标中，我们将 研究含有 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。这些实验具有高度创新性，因为它们是天然环状 RNA 在滚环机制中翻译的首次演示之一。这种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，不应该翻译。这些发现意义重大，因为它们可以为 FTDP-17 中生成 tau 聚集体的分子机制。尽管 FTDP-17 突变很少见， 它们可以被视为“自然实验”，这将有助于理解更常见的 tau 病理学 阿尔茨海默病。