Control of mitochondrial function in neurons by microRNAs during inflammation-induced neurodegeneration

多发性硬化症（MS）是中枢神经系统（CNS）最常见的炎症性疾病。炎症性损伤导致轴突和神经元的进行性变性，这是永久性神经功能障碍发展的关键。虽然很明显，炎症有助于神经元应激反应，导致线粒体功能障碍和能量消耗，但仍不清楚是哪些因素稳定了这些反应网络。microRNAs （miRNAs）调控是应激反应中调控mrna翻译活性和稳定性的重要机制。因此，我们旨在了解炎症过程中神经元基因表达的变化是如何被mirna调节的，以及这种调节是否会影响对线粒体功能至关重要的蛋白质表达，从而加强或改善神经退行性变。因此，表征miRNA在炎症诱导的神经元表达网络调节中的作用的第一步是通过排除其他细胞类型来全面表征匹配的mRNA和miRNA表达谱。因此，我们获得了健康小鼠不同神经元水平的mRNA和miRNA谱，并将其与ms动物模型实验性自身免疫性脑脊髓炎（EAE）小鼠进行了比较。利用新的遗传方法，我们可以直接从炎症和健康的CNS匀浆中分离神经元mRNA和miRNA。对这些神经元特异性mRNA和miRNA分离物进行下一代测序，为我们提供了前所未有的量化中枢神经系统炎症期间神经元转录物组成的方法。值得注意的是，在EAE模型期间，mRNA谱显示神经元中线粒体转录物的显着代表性不足。同时，这些转录本被预测为新发现的炎症诱导的神经元mirna的靶标。因此，我们现在建议进一步缩小我们的结果，通过紫外交联和免疫沉淀mRNA靶点及其特异性来自神经元的mirna，以揭示直接相互作用位点。为了从功能上表征mirna组成改变的影响，我们将在体外和体内研究最显著调节的mirna，破译它们对线粒体代谢功能和神经元保存或退化的贡献。总之，这将提供一种新的方法来理解miRNA对mRNA网络的控制，这些mRNA网络控制线粒体功能，并有助于中枢神经系统炎症期间的神经变性或保护。了解mirna在病理生理机制中的作用可能为疾病治疗提供一种新的治疗方式。

Multiple sclerosis (MS) is the most frequent inflammatory disease of the central nervous system (CNS). Inflammatory insults lead to progressive degeneration of axons and neurons that are key for the development of permanent neurological disability. While it is clear that inflammation contributes to neuronal stress responses resulting in mitochondrial dysfunction and energy depletion, it remains ill defined which factors stabilise these response networks. Regulation by microRNAs (miRNAs) is an important mechanism of regulating translational activity and stability of mRNAs during stress responses. Therefore, we aim at understanding how the changes of neuronal gene expression during inflammation are regulated by miRNAs and whether this regulation impacts on protein expression that are critical for mitochondrial function thereby reinforcing or ameliorating neurodegeneration. Accordingly, the first necessary step in the characterisation of the role of miRNAs in inflammation-induced regulation of expression networks in neurons is a comprehensive characterisation of matched mRNA and miRNA expression profiles by excluding other cell types. Hence, we acquired mRNA and miRNA profiles at the level of distinct neurons in healthy mice and compared them to mice with experimental autoimmune encephalomyelitis (EAE), the animal model of MS. By taking advantage of novel genetic methods allowed us to directly isolate neuronal mRNAs and miRNAs from inflamed and healthy CNS homogenates. Using next generation sequencing on these neuron-specific mRNA and miRNA isolates gave us a never before acquired quantification of transcript compositions in neurons during CNS inflammation. Notably, the mRNA profiles showed a significant underrepresentation of mitochondrial transcripts in neurons during the EAE model. At the same time these transcripts where predicted to be targets of newly identified inflammation-induced neuronal miRNAs. Therefore, we now propose to further narrow our results by UV crosslinking and immunoprecipitation of mRNA targets together with their miRNAs specifically from neurons to reveal direct interaction sites. In order to functionally characterise the impact of an altered composition of miRNAs, we will use in vitro and in vivo studies of the most significantly regulated miRNAs, deciphering their contribution to mitochondrial metabolic function and neuronal preservation or degeneration. Together, this will offer a new approach of understanding miRNA control of mRNA networks that govern mitochondrial function and contribute to neurodegeneration or -protection during CNS inflammation. Understanding the role of miRNAs in the pathophysiologic mechanisms may offer a new therapeutic modality for disease modification.