Altered Biogenesis and MicroRNA Content of Hippocampal Exosomes Following Experimental Status Epilepticus
Altered Biogenesis and MicroRNA Content of Hippocampal Exosomes Following Experimental Status Epilepticus
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DOI：
10.3389/fnins.2019.01404
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发表时间：
2020-01-17
影响因子：
4.3
通讯作者：
Henshall, David C.
中科院分区：
文献类型：
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作者：
Batool, Aasia;Hill, Thomas D. M.;Henshall, David C.
反复或长时间的癫痫发作(癫痫持续状态)会损害海马区的神经元，引发神经胶质细胞增多症，并产生持久的过度兴奋状态。最近的研究表明，在刺激和组织损伤后，脑细胞会释放包括外切体在内的微囊，在细胞之间传递内容，包括microRNAs(MiRNAs)。在这里，我们表征了实验性癫痫持续状态对外切体生物合成成分表达的影响，并分析了富含外切体的组分中的miRNA含量。单侧杏仁核内注射海人酸致小鼠癫痫持续状态，导致海马区与外体生物合成相关的急性亚场特异性双向改变，包括上调转运所需的内体分选复合体(ESCRT)依赖和非依赖通路。在癫痫持续状态2周后的样本中，检测到包括Alix在内的外切体成分的表达增加，并且同侧和对侧的海马区都发生了变化。用两种不同的技术制备的富含外切体组分的RNA测序检测到了丰富的保守miRNAs的多样性，并表明癫痫持续状态选择性地改变了miRNA的含量。我们还对富含外切体的miRNAs的编辑位点进行了表征，发现了6个富含外切体的miRNAs是腺苷到肌苷(ADAR)编辑的，大多数编辑事件预计将发生在miRNA种子区域内。然而，这些编辑事件的发生率并不因癫痫持续状态而改变。这些研究表明，癫痫持续状态会改变外体途径及其miRNA含量，但不会改变编辑模式。需要进一步的功能研究来确定这些变化是否对癫痫的发生具有病理生理学意义。
Repetitive or prolonged seizures (status epilepticus) can damage neurons within the hippocampus, trigger gliosis, and generate an enduring state of hyperexcitability. Recent studies have suggested that microvesicles including exosomes are released from brain cells following stimulation and tissue injury, conveying contents between cells including microRNAs (miRNAs). Here, we characterized the effects of experimental status epilepticus on the expression of exosome biosynthesis components and analyzed miRNA content in exosome-enriched fractions. Status epilepticus induced by unilateral intra-amygdala kainic acid in mice resulted in acute subfield-specific, bi-directional changes in hippocampal transcripts associated with exosome biosynthesis including up-regulation of endosomal sorting complexes required for transport (ESCRT)-dependent and -independent pathways. Increased expression of exosome components including Alix were detectable in samples obtained 2 weeks after status epilepticus and changes occurred in both the ipsilateral and contralateral hippocampus. RNA sequencing of exosome-enriched fractions prepared using two different techniques detected a rich diversity of conserved miRNAs and showed that status epilepticus selectively alters miRNA contents. We also characterized editing sites of the exosome-enriched miRNAs and found six exosome-enriched miRNAs that were adenosine-to-inosine (ADAR) edited with the majority of the editing events predicted to occur within miRNA seed regions. However, the prevalence of these editing events was not altered by status epilepticus. These studies demonstrate that status epilepticus alters the exosome pathway and its miRNA content, but not editing patterns. Further functional studies will be needed to determine if these changes have pathophysiological significance for epileptogenesis.