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53种人类微管相关蛋白tau基因（MAPT）突变可导致额颞叶痴呆，其特征是行为障碍、认知障碍和帕金森病。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。我们最近报道了人类MAPT产生两种人类特异性环状rna，这是由外显子12与外显子7或10的反剪接引起的。