Role of Mettl3-dependent RNA m6A dysregulation in Alzheimer's disease

项目总结/摘要 作为一种复杂的多因素疾病，遗传、环境和生活方式因素的结合影响着 通过基因中复杂的转录和翻译变化， 然而，AD脑中的表达，这些变化背后的机制仍然难以捉摸。类似于 DNA和组蛋白修饰，RNA修饰也可能导致基因表达的改变， 允许基因表达的额外调节层。N6-甲基腺苷（m6 A）是最常见的内源性腺苷酸。 在真核生物mRNA中的修饰，其调节RNA稳定性、加工、定位、翻译。是 参与各种生物过程，包括线粒体功能、突触功能和认知功能。 功能，但RNA m6 A修饰在衰老和年龄相关的神经退行性变中的潜在作用 包括AD在内的疾病在很大程度上尚未探索。我和其他几个小组的研究表明， 胃L3-m6 A失调是AD病程中的早期事件。胃内L3敲低 海马引起AD相关的认知功能障碍和神经退行性变，而胃L3过表达 挽救了Aβ O诱导的神经元/突触和认知/行为缺陷，表明 AD发病机制中的L3-m6 A失调许多AD相关基因的mRNA都含有m6 A 提示胃L3依赖性m6 A修饰可能对AD相关的多个方面具有影响。 鉴于线粒体功能障碍在AD的发病机制中起着关键作用， 注意到甲基化谱鉴定了线粒体关键调控因子mRNA中的多个m6 A位点， 包括参与线粒体生物发生的功能（即，PGC 1 α和TFAM）和线粒体 动态（即，Mfn 2和DLP 1）。事实上，胃L3敲低导致线粒体片段化， 功能障碍可能通过调节PGC 1 α和Mfn 2的表达，这可能有助于Aβ 寡聚体诱导的线粒体功能障碍。基于这些研究，我们假设， 胃L3-m6 A信号调节线粒体调节因子的表达， 线粒体功能障碍与AD的发病机制。因此，胃L3过表达挽救了 m6 A信号传导和线粒体基因表达和功能，并消除AD相关的缺陷。 我们将确定AD中胃L3减少的潜在机制，并探讨是否以及如何 减少的胃L3介导AβO对AD中线粒体生物发生/动力学和功能的毒性作用。 前脑中存在胃L3过表达的新型动物模型将与AD转基因小鼠杂交 模型和仔细的特点。这项研究的成功完成将提供新的机制， 深入了解AD中基因表达的变化，并可能将胃L3-m6 A信号转导作为一种新的治疗方法。 有希望的治疗目标的药物开发在AD，这也有影响的研究其他 神经退行性疾病和一般的衰老。

PROJECT SUMMARY/ABSTRACT As a complex and multifactorial disease, a combination of genetics, environmental and lifestyle factors affect ones’ risk of developing AD through complex transcriptional and translational changes in the gene expression in AD brain, however, the mechanisms underlying these changes remain elusive. Analogous to DNA and histone modifications, RNA modifications could also lead to alterations in gene expression which allows extra layers of regulation of gene expression. N6-methyladenosine (m6A) is the most common internal modification in eukaryotic mRNAs which regulates RNA stability, processing, localization, translation. It is involved in various biological processes including mitochondrial function, synaptic function and cognitive function, but the potential role of RNA m6A modification in aging and age-related neurodegenerative diseases including AD is largely unexplored. Studies from my group and several other groups demonstrated METTL3-m6A dysregulation is an early event during the course of AD. METTL3 knockdown in the hippocampus caused AD-related cognitive deficits and neurodegeneration while METTL3 overexpression rescued AβO-induced neuronal/synaptic and cognitive/behavioral deficits, suggesting a critical role of METTL3-m6A dysregulation in the pathogenesis of AD. mRNA of many AD-related genes contain m6A suggesting that METTL3-dependent m6A modification likely have impacts on multiple aspects related to AD. Given that mitochondrial dysfunction plays a critical role in the pathogenesis of AD, it is of particular interest to note that methylation profiling identified multiple m6A sites in mRNAs of key regulators of mitochondrial functions including those involved in mitochondrial biogenesis (i.e., PGC1α and TFAM) and mitochondrial dynamics (i.e., Mfn2 and DLP1). Indeed, METTL3 knockdown caused mitochondrial fragmentation and dysfunction likely through modulation of PGC1α and Mfn2 expression which could contribute to Aβ oligomers-induced mitochondrial dysfunction. Based on these studies, we hypothesized that reduced METTL3-m6A signaling modulates the expression of mitochondrial regulators and contributes to mitochondrial dysfunction and the pathogenesis of AD. Therefore, METTL3 overexpression rescues m6A signaling and mitochondrial gene expression and function and alleviates AD-related deficits. We will determine the mechanisms underlying METTL3 reduction in AD and explore whether and how reduced METTL3 mediates toxic effects of AβO on mitochondrial biogenesis/dynamics and function in AD. Novel animal models with METTL3 overexpression in the forebrain will be crossed with AD transgenic mouse models and carefully characterized. The successful completion of this study will provide novel mechanistic insights into changes in gene expression in AD and will likely establish METTL3-m6A signaling as a promising therapeutic target for drug development in AD, which also have implications of studying other neurodegenerative disorders and aging in general.