MicroRNA-206对实验性心房颤动犬心脏内在自主神经重构的影响及机制研究

The mechanism of atrial fibrillation (AF) included not only known electrical and structural remodeling, but nerve remodeling also happened. However, the molecular mechanism of the nerve remodeling was still unclear. MicroRNA (miRNA) as an uncoding small RNA, controlled many protein-coding genes. Studies have found that the miR-206 had the specific expression in the central and peripheral nervous system, and influenced nerve regeneration process after the nerve damage by regulating target genes and downstream molecules. Based on our preliminary studies such as "Functional connections of the cardiac autonomic nervous system and their influences on cardiac electrophysiological properties", our group propose the hypothesis that miR-206 regulate the intrinsic cardiac autonomic nervous system. We intend to develop the experimental AF model in canine, transfect miR-206 mimics and inhibitors in canine atrial ganglioned plexus, and detect the expression of miR-206 and its target genes such as SOD-1, BDNF and FGFBP1, and downstream molecules, to validate their coordinative effect on regulating target genes. We will change the miR-206 expression level, to observe its effects on molecular markers and related index of nerve remodeling, clarify the influence of the miR-206 on the nerve remodeling and the molecular mechanism of the nerve remodeling, and provide new explanation for the occurrence and maintain of AF.

心房颤动（房颤）的机制除了电与结构重构，也有内在自主神经的重构，但其机制不明。MicroRNA（miRNA）作为一种非编码的小RNA，能够调控多个蛋白编码基因。研究发现其中的miR-206在中枢及外周神经系统均有特异表达，并在神经损伤后通过调控靶基因及下游通路的表达来影响神经再生。本课题组在"心脏自主神经系统之间的功能联系及其对心脏电生理特性的影响"等课题的研究基础上，提出miR-206调控心脏内在自主神经系统的假说。拟通过制作实验性房颤犬模型，心房神经丛内转染miR-206的类似物及抑制物，检测miR-206与SOD-1、BDNF、FGFBP1等靶基因及其下游通路的表达，验证miR-206对靶基因的协同调控作用。通过改变miR-206的表达水平，观察其对神经再生分子标记及相关指标的影响，阐明miR-206对心脏内在自主神经重构的影响及其调控的分子机制，为房颤的发生和维持提供新的解释。

心房颤动（房颤）是最严重的心房电活动紊乱，具有较高的致残率与死亡率，但发生机制仍不十分明了。研究发现心房结构重构与电重构在房颤的发生与维持中具有重要作用。近来，心脏内在自主神经重构，即心脏交感与迷走神经的再生与不均一分布，被证实为房颤的重要发病机制。MicroRNA(miRNA)是生物体内一类较短的内源性非编码小分子RNA，在转录后水平对基因表达进行负调控。 大量证据表明，多种miRNA参与房颤的心房结构重构与电重构的发病过程，并在神经系统疾病的发病中扮演重要角色。心脏内在自主神经系统是否有miRNA的不同程度表达，及对房颤的发生与发展有何作用，至今仍无具体研究结论。本研究旨在探讨持续性快速右心房起搏后犬上左神经丛（SLGP）是否发生神经重构，并从miRNAs的角度研究房颤内在自主神经的重构的分子机制，为房颤的治疗提供理论依据。本课题通过建立实验性房颤犬的模型，利用高通量测序、免疫组化等方法， 发现房颤犬心脏神经丛部位发生明显的神经重构现象，其中 6种miRNA的表达明显上调，10种miRNA的表达明显下调，其中miR-206上调表达最明显，并应用RT-PCR验证该测序结果，提示差异表达的miRNAs可能参与房颤内在自主神经重构。进一步通过体内感染与体外转染miR-206过表达与沉默慢病毒，通过免疫组化及电生理检测发现miR-206能够促进心脏自主神经重构，并能易化房颤的发生。利用GO分析及KEGG 通路分析预测到miR-206可通过多条信号通路影响心脏自主神经重构过程。利用荧光素酶分析报告、RT-PCR与Western Blot等技术，验证SOD1和GCH1是miR-206的靶基因，miR-206的过表达能够下调SOD1和GCH1的表达，进而分别影响ROS、BH4等下游通路来促进神经再生，易化房颤发生。这些研究结果均提示，miR-206通过多种信号通路参与了房颤自主神经重构。