The miR-92a–Cpeb3 network in inflammation-induced neurodegeneration

多发性硬化症（MS）是最常见的中枢神经系统（CNS）炎症性疾病，其特点是广泛的神经系统症状。这些主要是由炎症驱动的神经轴突和突触损伤引起的，与流行的MS亚型无关。由于现有的免疫调节药物不能充分缓解MS的进展，神经保护干预是一个迫切的未满足的需求。因此，揭示抗炎症性神经退行性变的神经元内在保护机制，有望定制神经保护药物，最终阻止神经系统的进展。最近，我们证明炎症应激导致广泛的神经元特异性转录和翻译反应。一种以细胞特异性方式快速重新平衡这种炎症扰动的机制是通过microRNAs （miRNAs）对mRNA转录物的转录后调节。然而，关于神经元mirna的功能作用及其依赖的调控途径的知识很少，但可以揭示这种神经保护药物靶点。由于这些原因，在我们之前资助的项目中，我们分析了中枢神经系统炎症中神经元特异性miRNA-mRNA网络，从而发现了miR-92a-Cpeb3网络。功能分析显示，在EAE过程中，miR-92a在神经元中被诱导，并在谷氨酸应激下转录上调。此外，它对谷氨酸诱导的神经元细胞死亡具有很强的保护作用。通过详细的生物信息学分析和随后的验证，我们发现rna结合蛋白Cpeb3是miR-92a的重要靶转录物，在EAE期间和神经元谷氨酸应激时，miR-92a在神经元中下调。与miR-92a过表达一致，原代神经元中Cpeb3缺失显示谷氨酸应用后存活率提高。通过基因缺失小鼠，我们还观察了miR-92a和Cpeb3对EAE小鼠临床结局的相互作用。然而，新发现的miR-92a-Cpeb3网络如何调节神经变性的许多不同方面仍然是谜。因此，在这个更新的应用中，我们建议确定这个网络的细胞调节和空间特异性，并描绘下游成分。然后将对其神经保护特性进行机械解剖。我们将在临床前研究以及人体细胞和组织中进一步探索和验证我们的发现。除了有机会通过将我们的机制发现转化为神经保护药物靶点来干预炎症诱导的神经变性外，本研究还对神经元miRNA-mRNA网络的基本原理及其对神经元信号传导和存活的贡献提供了深远的见解。

Multiple sclerosis (MS) is the most common inflammatory disease of the central nervous system (CNS), which is characterized by a wide spectrum of neurological symptoms. These are primarily caused by inflammation-driven neuroaxonal and synaptic injury, irrespective of prevailing MS subtype. Since progression of MS is not sufficiently mitigated by the existing immunomodulatory drugs, neuroprotective interventions are an urgent unmet need. Therefore, revealing neuron-intrinsic mechanisms of protection against inflammation-induced neurodegeneration, holds the promise to tailor neuroprotective drugs that can eventually halt neurological progression. Recently, we demonstrated that inflammatory stress results in a broad neuron-specific transcriptional and translational response. A mechanism that quickly rebalances such inflammatory perturbations in a cell-specific manner is post-transcriptional regulation of mRNA transcripts by microRNAs (miRNAs). However, knowledge about the functional role of neuronal miRNAs and its dependent regulatory pathways is sparse, but could reveal such neuroprotective drug targets. For these reasons, in our previously funded project, we profiled neuron-specific miRNA–mRNA networks in CNS inflammation, which led to the discovery of the miR-92a–Cpeb3 network. Functional analyses revealed that miR-92a is induced in neurons during EAE and transcriptionally upregulated by glutamate stress. Moreover, it strongly protected from glutamate-induced neuronal cell death. By elaborate bioinformatic analyses and subsequent validation, we identified the RNA-binding protein Cpeb3 as a prominent target transcript of miR-92a that was downregulated in neurons during EAE and upon neuronal glutamate stress. Consistent with miR-92a overexpression, Cpeb3 deletion in primary neurons revealed improved survival upon glutamate application. Using gene-deleted mice we also observed the reciprocal effects of miR-92a and Cpeb3 on the clinical outcome of EAE mice. However, many different aspects of how the newly discovered miR-92a–Cpeb3 network modulates neurodegeneration remains enigmatic. Thus, in this renewal application, we propose to identify the cellular regulation and spatial specificity of this network as well as to profile the downstream components. These will then be mechanistically dissected for their neuroprotective properties. We will further explore and validate our findings in preclinical studies as well as in human cells and tissues. Besides the opportunity to intervene in inflammation-induced neurodegeneration by translating our mechanistic findings into neuroprotective drug targets, this research offers far-reaching insights into basic principles of neuronal miRNA–mRNA networks and their contribution to neuronal signaling and survival.