Mechanisms underlying circular RNA biogenesis in Alzheimer’s disease related genes

阿尔茨海默病相关基因中环状 RNA 生物发生的机制

• 批准号: 10665204
• 负责人: Paul Nils Valdmanis
• 金额: $ 22.77万
• 依托单位: UNIVERSITY OF WASHINGTON
• 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/10665204
• 关键词: Affect; Alternative Splicing; Alzheimer' s Disease; Alzheimer' s Disease Pathway; Alzheimer' s disease brain; Alzheimer' s disease patient; Amyloid beta-Protein; Biogenesis; Brain; Cell Line; Cells; Code; Complement; Disease; Etiology; Evaluation; Event; Exons; Generations; Genes; Genetic Transcription; High-Throughput RNA Sequencing; Hippocampus; Human; Hypoxia; In Vitro; Individual; Knowledge; Large-Scale Sequencing; Late Onset Alzheimer Disease; Mediating; Messenger RNA; Neurodegenerative Disorders; Neurons; Oxidative Stress; Pathogenesis; Pathogenicity; Pathology; Patients; Prevalence; Process; Production; Protein Isoforms; Proteins; RNA; RNA Helicase; RNA Splicing; Regulation; Regulatory Element; Repetitive Sequence; Role; Sampling; Series; Study models; Synapses; Synaptosomes; Testing; Therapeutic; Tissues; Transcript; Translations; Untranslated RNA; Variant; abeta accumulation; brain tissue; circular RNA; design; differential expression; effective therapy; frontal lobe; glycogen synthase kinase 3 beta; glycogen synthase kinase 3 beta inhibitor; mRNA Translation; mouse model; novel; novel therapeutic intervention; physiologic stressor; presenilin-2; preservation; prevent; repository; tau Proteins; tau aggregation; tau expression; tau-1; transcriptome; transcriptome sequencing; vector

Alzheimer’s disease (AD) is a debilitating and pervasive neurodegenerative disorder with no effective treatments and is predicted to double in prevalence over the next 30 years. One of the first hallmarks of AD is loss of synapses followed by amyloid beta aggregation and tau neurofibrillary tangles. The steps leading to these aggregation events, especially in individuals with late-onset AD, are poorly understood. To better comprehend the transcriptional mechanisms associated with synapse loss, we isolated synapses in the form of synaptosomes and performed high throughput RNA sequencing. We found differentially expressed mRNAs associated with the synapse in AD patients with implications for synaptic transport and local mRNA translation. Notably, when interrogating the noncoding transcriptome, we found a widespread shift of distribution of circular RNAs (circRNAs) from cell bodies to synapses. CircRNAs are stable molecules formed from covalent linkages of conserved back-spliced exon junctions that can compete with linear counterparts. Interestingly among the top differentially expressed circRNAs were two circRNAs from GSK3β, which underwent a switch from one isoform significantly upregulated in AD to another significantly downregulated. GSK3β phosphorylation of tau is essential for its aggregation and GSK3β inhibitors have actively been pursued as translational targets for AD. Further evaluation of GSK3β and other circular RNAs in a large RNAseq repository revealed differentially expressed circRNAs in PSEN2 surrounding exons associated with hypoxia mediated alternative splicing. Therefore, key AD associated proteins have RNA counterparts at the synapse that are differentially expressed that may have critical modulatory roles. Our findings point to a novel mode of regulation at the RNA level. Through a series of in vitro studies and mouse models of tau pathology, we propose to therapeutically modulate the expression of circGSK3B and circPSEN2 isoforms to restore appropriate regulation of tau. We propose to ascertain whether regulatory features surrounding alternative GSK3β exons affect circRNA production and whether RNA helicases influence the GSK3β circRNA isoform switch that we observe. In addition, we will evaluate the relationship between PSEN2 circRNA biogenesis and the role of oxidative stress in affecting aberrant PSEN2 alternative splicing – a phenomenon we observe to be significantly enriched in sporadic AD. Collectively, we will leverage our understanding of the rules governing circRNA biogenesis and regulation to generate molecules capable of preserving appropriate expression of GSK3β and prevent tau aggregation.

阿尔茨海默病（AD）是一种使人衰弱的普遍性神经退行性疾病，目前尚无有效的治疗方法 治疗，预计在未来 30 年患病率将翻倍。最早的标志之一 AD 是突触丧失，随后出现β 淀粉样蛋白聚集和tau 神经原纤维缠结。步骤 导致这些聚集事件的原因，特别是在患有迟发性 AD 的个体中，人们知之甚少。 为了更好地理解与突触丢失相关的转录机制，我们分离了突触 以突触体的形式进行高通量RNA测序。我们发现差异 AD 患者中表达的与突触相关的 mRNA 对突触运输和 局部 mRNA 翻译。值得注意的是，当询问非编码转录组时，我们发现了广泛存在的 环状 RNA (circRNA) 的分布从细胞体转移到突触。 CircRNA 稳定 由保守的反向剪接外显子连接的共价连接形成的分子，可以与 线性对应物。有趣的是，差异表达最高的 circRNA 中有两个来自 GSK3β，从 AD 中显着上调的一种异构体转变为另一种显着上调的异构体 下调。 tau 蛋白的 GSK3β 磷酸化对其聚集至关重要，GSK3β 抑制剂具有 积极追求作为 AD 的转化目标。 GSK3β 和其他环状 RNA 的进一步评估 在大型 RNAseq 存储库中揭示了 PSEN2 外显子周围差异表达的 circRNA 与缺氧介导的选择性剪接有关。因此，关键的 AD 相关蛋白具有 RNA 突触上差异表达的对应物可能具有关键的调节作用。我们的 研究结果指出了 RNA 水平上的一种新的调控模式。通过一系列的体外研究和 在 tau 病理学小鼠模型中，我们建议治疗性调节 circGSK3B 和 circPSEN2 同种型恢复 tau 的适当调节。我们建议确定监管是否 围绕替代 GSK3β 外显子的特征影响 circRNA 的产生以及 RNA 解旋酶是否 影响我们观察到的 GSK3β circRNA 同种型开关。此外，我们还会评估双方的关系 PSEN2 circRNA生物合成与氧化应激在影响异常PSEN2中的作用之间的关系 选择性剪接——我们观察到这种现象在散发性 AD 中显着丰富。总的来说， 我们将利用我们对 circRNA 生物发生和调控规则的理解来生成 能够保持 GSK3β 适当表达并防止 tau 聚集的分子。