CircRNA_itsn1及其靶向基因ITSN1在术后认知功能障碍发生中的作用及机制研究

Postoperative cognitive dysfunction (POCD) is a severe complication of elderly patients after surgery, which is a crucial need to clarify its pathogenesis. The important role of circular RNAs (circRNAs) in neurodegenerative disease is becoming more and more prominent. Through combined analysis of the Arraystar Human circRNA/mRNA Microarray, we have identified upregulation of the circRNA, which we named circRNA_itsn1, and its targeted ITSN1 in the plasma of the elderly patients with POCD. Meanwhile, our previous study also demonstrated that downregulation of ITSN1 through perioperative injection of ITSN1 siRNA to the CA1 region of dorsal hippocampus had significantly mitigated cognitive dysfunction in aged mice, suggesting that circRNA_itsn1 and its targeted ITSN1 may be involved in the development of POCD. In this project, we will further conduct the experiments from the molecular, cellular, and tissue levels to determine the increase of circRNA_itsn1 and ITSN1 levels and their relationship with the POCD. Also, we will probe the possible mechanisms for the development of POCD mediated by circRNA_itsn1 and ITSN1. Furthermore, means of regulation of ITSN1 by circRNA_itsn1 and related molecular mechanisms will be determined in our designed experiments. The successful implementation of this project will enrich and expand the existing research ideas and mechanisms of POCD.

术后认知功能障碍（POCD）是老年患者术后严重并发症，亟需明确发病机制。环状RNA(circRNAs)在神经退行性疾病的重要作用日益突显。我们前期通过Arraystar Human circRNA/mRNA芯片联合分析，初步确定了POCD老年患者术后血浆中表达上调的circRNA（命名为circRNA_itsn1）及靶基因ITSN1；同时围术期下调ITSN1 (siRNA干扰)可显著改善老年小鼠术后认知功能，这提示circRNA及其靶基因ITSN1可能参与介导POCD的发生。本课题拟进一步从整体、细胞和分子不同层面，明确围术期因素引起circRNA_itsn1和ITSN1表达变化及其与POCD的关系，探讨circRNA_itsn1和ITSN1介导POCD发生的可能机制，阐明circRNA_itsn1调控ITSN1的作用方式及分子机制。本项目的成功实施将丰富和拓展POCD现有研究思路和机制。

术后认知功能障碍（POCD）是老年患者术后严重并发症，亟需明确发病机制。寻找调控POCD 的关键因子，探索潜在的信号通路，发现有效的干预靶点，对POCD的防治至关重要。我们通过对POCD及非POCD老年手术患者进行Arraystar Human circRNA/mRNA芯片联合分析，初步确定了POCD老年患者术后血浆中表达上调的hsa_circRNA_00061570 （命名为circRNA_itsn1）及靶基因ITSN1。此外，我们通过老年小鼠单肾切除术建立POCD模型，发现hsa_circRNA_00061570同源转化小鼠circRNA，即mmu_circRNA_0006466和其亲本基因ITSN1在小鼠中枢神经系统同样表达上调，就此提出在POCD过程中中枢神经系统circRNA_itsn1表达上调，正向调控了相关基因ITSN1的表达，介导海马神经元突触可塑性损伤，进而导致POCD的发生。在POCD的发病过程中，小鼠海马组织CA1区，mmu_circRNA_0006466的水平、ITSN1及ITSN1下游JNK通路蛋白均显著升高，突触相关蛋白表达降低，我们利用多种动物神经认知行为学实验、海马立体定位注射AAV病毒及小鼠海马神经元细胞系感染慢病毒等技术证实降低ITSN1及mmu_circRNA_0006466的表达均可改善小鼠的认知障碍及突触损伤发生情况。此外，我们通过RIP实验、原位杂交及免疫荧光共聚焦、放射菌素D实验进一步证实了mmu_circRNA_0006466可通过EIF4A3结合蛋白增加ITSN1 mRNA稳定性，进而正向调控ITSN1的表达。综上，我们发现ITSN1及其相关circRNA_itsn1可能通过激活JNK通路，导致中海马突触可塑性损伤，进而介导POCD的产生。此研究将为POCD的发生机制研究提供的新的方向和理论基础。