The tRNA pool in C9-ALS/FTD

C9-ALS/FTD 中的 tRNA 池

• 批准号: 10662716
• 负责人: Ya-Ming Hou
• 金额: $ 24.92万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10662716
• 关键词: ALS patients; Address; Adult; Affect; Aging; Amino Acids; Amyotrophic Lateral Sclerosis; Animal Model; Anticodon; Award; Base Sequence; Biological Models; Biology; Brain; C9ORF72; Cell model; Cells; Charge; Chemicals; Chimeric Proteins; Codon Nucleotides; Cognitive; Data; Development; Dipeptides; Disease; Disease Outcome; Foundations; Frontotemporal Dementia; Genes; Genetic; Genetic Transcription; Initiator Codon; Introns; Length; Link; Mediating; Medical; Messenger RNA; Modeling; Modification; Neurodegenerative Disorders; Neuronal Differentiation; Nucleosides; Nucleotides; Onset of illness; Pathogenesis; Pathology; Patients; Positioning Attribute; Protein Biosynthesis; Proteins; RNA; Reading Frames; Regulation; Reporter; Research; Ribosomal Frameshifting; Ribosomal Proteins; Ribosomes; Role; Running; Sampling; Secure; Temporal Lobe; Testing; Therapeutic; Therapeutic Intervention; Time; Tissues; Transfer RNA; Transfer RNA Aminoacylation; Translating; Translation Initiation; Translations; United States National Institutes of Health; Work; bench to bedside; curative treatments; design; frontal lobe; frontier; frontotemporal lobar dementia amyotrophic lateral sclerosis; genome-wide analysis; improved; induced pluripotent stem cell; insight; interest; loss of function; methyl group; motor neuron degeneration; novel; novel therapeutics; posttranscriptional; programs

PROJECT SUMMARY The C9orf72-mediated ALS (amyotrophic lateral sclerosis) and FTD (frontotemporal dementia) (C9- ALS/FTD) are two fatal neurodegenerative diseases with no curative treatment. We aim to address a new mechanism at the core of C9-ALS/FTD to improve the therapeutic potential. While ALS is an adult-onset disease with progressive degeneration of motor neurons, and while FTD is characterized with progressive decline of the frontal and temporal lobes of the brain, the two share a common genetic cause – repeat expansion of the nucleotide sequence G4C2 in the first intron of the C9orf72 gene. Of the proposed causes of C9-ALS/FTD, the most significant is the synthesis of dipeptide repeat (DPR) proteins from ribosome translation of the expanded repeats. These DPRs are consistently observed in patient tissues and in various model systems. While the initiation of DPR synthesis is non-canonical, the elongation of protein synthesis is by the classical ribosome machinery that translates each codon using a set of tRNA species with the matching anticodon, which is provided by the cellular tRNA pool. Notably, translation of repeated sequences is highly challenging, requiring repeated use of the tRNAs for the same codon, where each species must be efficiently charged and post-transcriptionally modified and matured. This challenge is further intensified in patient cells, where the repeat length can run up to thousands, raising the question of how the cellular tRNA pool responds to such an unusual demand. This is an unexplored, but critical, question in C9-ALS/FTD, because the deficiency of quality tRNAs can shift the ribosome translational reading-frame, leading to frameshifting and synthesis of chimeric DPRs that would alter the disease pathology. Here we will address this question, based on our extensive expertise in tRNA and in tRNA-associated ribosome frameshifting. In Aim 1, we will determine changes of the tRNA pool in C9 patient-derived cells relative to an isogenic control, using our improved tRNA-seq. We will also decipher changes of the ribosome-mediated global protein synthesis that underlie the disease. We will determine changes both in the iPSC (induced pluripotent stem cell) state and in the differentiated neuron (iPSN) state, due to their fundamental differences in regulation of protein synthesis, and due to the potential to produce new insight into the disease during differentiation. In Aim 2, we will test the hypothesis that the course of DPR synthesis can be induced to undergo a desired frameshifting to produce less toxic proteins that can reduce the disease pathology. We will test how changes of the abundance and charging levels of the tRNAs required for DPR synthesis can induce the desired frameshifting. This work will serve as the foundation for understanding the therapeutic implications of tRNA and ribosome protein synthesis in the development of C9-ALS/FTD, providing a template that is generalizable to other aging and neurodegenerative diseases associated with nucleotide repeat expansions.

项目摘要 C9 orf 72介导的ALS（肌萎缩侧索硬化）和FTD（额颞叶痴呆）（C9- ALS/FTD）是两种致命的神经退行性疾病，目前尚无治愈方法。我们的目标是解决一个新的 C9-ALS/FTD的核心机制，以提高治疗潜力。虽然ALS是一种成人发病的疾病， 伴随运动神经元的进行性变性，而FTD的特征是运动神经元的 大脑的额叶和颞叶，两者有一个共同的遗传原因--重复扩张 C9 orf 72基因的第一内含子中的核苷酸序列G4 C2。在C9-ALS/FTD的拟定病因中， 最重要的是从扩增的核糖体翻译合成二肽重复序列（DPR）蛋白。 重复。在患者组织和各种模型系统中始终观察到这些DPR。而 DPR合成的起始是非典型的，蛋白质合成的延伸是通过经典的核糖体 使用一组具有匹配反密码子的tRNA种类翻译每个密码子的机器， 细胞内的tRNA库。值得注意的是，重复序列的翻译是高度挑战性的，需要重复翻译。 使用相同密码子的tRNA，其中每个物种必须有效地带电并在转录后 修改和成熟。这种挑战在患者细胞中进一步加剧，其中重复长度可高达 这就提出了一个问题，即细胞中的tRNA库如何应对这种不寻常的需求。这是一 C9-ALS/FTD中一个尚未探索但至关重要的问题，因为缺乏优质tRNA会使核糖体移位， 翻译阅读框，导致移码和嵌合DPR的合成，这将改变疾病 病理在这里，我们将解决这个问题，根据我们在tRNA和tRNA相关的广泛的专业知识， 核糖体移码在目标1中，我们将确定C9患者来源的细胞中tRNA库相对于C9患者来源的细胞的变化。 与同基因对照组进行比较。我们还将破译核糖体介导的 全球蛋白质的合成是疾病的基础。我们将确定iPSC（诱导的） 多能干细胞）状态和分化神经元（iPSN）状态，由于它们在 调节蛋白质合成，并由于潜在的产生新的见解疾病期间， 分化在目标2中，我们将测试DPR合成过程可以被诱导进行的假设。 期望的移码以产生毒性较小的蛋白质，其可以减少疾病病理。我们将测试如何 DPR合成所需的tRNA的丰度和电荷水平的变化可以诱导所需的 移码这项工作将作为理解tRNA治疗意义的基础， 核糖体蛋白合成在C9-ALS/FTD的发展，提供了一个模板，可推广到 其他与核苷酸重复扩增相关的衰老和神经退行性疾病。