Hippocampal neurons, Illumina experiments

Ongoing neuronal activity during development and plasticity acts to refine synaptic connections and contributes to the induction of plasticity and ultimately long term memory storage. Activity-dependent post-transcriptional control of mRNAs occurs through transport to axonal and dendritic compartments, local translation, and mRNA stability. We have identified a mechanism that contributes to activity-dependent regulation of mRNA stability during synaptic plasticity. In this study we demonstrate rapid, post-transtriptional control over process-enriched mRNAs by neuronal activity. Systematic analysis of the 3'-UTRs of destablized transcripts, identifies enrichment in sequence motifs corresponding to miRNA binding sites. The miRNAs that were identified, miR-326-3p/miR-330-5p, miR-485-5p, miR-666-3p, and miR-761 are predicted to regulate networks of genes important in plasticity and development. We find that these miRNAs are developmentally regulated in the hippocampus, many increasing by postnatal day 14. We further show that miR-485-5p controls NGF-induced neurite outgrowth in PC12 cells, tau expression, and axonal development in hippocampal neurons. miRNAs can function at the synapse to rapidly control and affect short- and long-term changes at the synapse. These processes likely occur during refinement of synaptic connections and contribute to the induction of plasticity and learning and memory.发育与突触可塑性过程中的持续神经元活动，可介导突触连接的精细化重塑，并参与可塑性的诱导，最终助力长期记忆的储存。mRNA的活性依赖型转录后调控，可通过将mRNA转运至轴突与树突区室、进行局部翻译以及调控mRNA稳定性来实现。本研究团队已发现一种可介导突触可塑性过程中mRNA稳定性活性依赖调控的机制。在本研究中，我们证实神经元活动可对富集于神经突起的mRNA实施快速的转录后调控。通过对不稳定转录本的3'-非翻译区（3'-Untranslated Regions, 3'-UTRs）进行系统性分析，我们发现其中富集有与微小RNA（microRNA, miRNA）结合位点相对应的序列基序。所鉴定出的miRNA包括miR-326-3p/miR-330-5p、miR-485-5p、miR-666-3p以及miR-761，它们被预测可调控与可塑性及发育密切相关的基因网络。我们发现这些miRNA在海马体中呈现发育阶段依赖性表达，其中多数在出生后第14天表达量升高。我们进一步证实，miR-485-5p可调控神经生长因子（Nerve Growth Factor, NGF）诱导的PC12细胞神经突起生长、tau蛋白表达，以及海马神经元的轴突发育。miRNA可在突触处发挥功能，快速调控并影响突触的短时与长时变化。这类过程大概率发生于突触连接的精细化重塑过程中，并对可塑性的诱导以及学习记忆过程产生贡献。