miR-101在心房颤动心房电重构中的作用及机制研究

Atrial fibrillation (AF) is the most commonly encountered clinical arrhythmia associated with pronounced morbidity, mortality, and socio-economic burden. This pathological entity is associated with an altered expression profile of genes that are important for atrial function. MicroRNAs (miRNAs), a new class of non-coding mRNAs of around 22 nucleotides in length, have rapidly emerged as one of the key players in the gene expression regulatory network. The potential roles of miRNAs in controlling AF have recently been investigated. In the present study we found that the current density of SK channels was increased in patients with persistent atrial fibrillation and the expression level were decreased. Lu et.al reported that miR-101 was downregulated by at least 50% AF dogs. Computational prediction identified SK3 encoding protein KCNN3 as a potential target for miR-101.We supposed that miR-101 is involved in AF and the associated atrial electeical remodeling by regulating SK3. In this study, we will regulate the expression of miR-101 by application of adenovirus plasmid pBHGlox- EGFP-U6-miR-101and antisense oligomers(AMO-101) to the atrium to check the effect to the expression and current of SK3,and whether it can enhance the AF vulnerability. Then use luciferase analysis to check the direct interact of miR-101 and SK3. The study therefore uncovered a novel molecular mechanism for AF and indicated miR-101 as a potential therapeutic target for AF.

心房颤动存在有心脏的电重构，心房电重构在房颤的发生和维持中起着重要作用，microRNA可能是房颤发生和维持机制中的新的潜在靶点。前期研究证实小电导钙激活钾通道（SK）参与了心房的电重构过程，其在持续性房颤的人体心房组织中电流密度增加而表达下调，而miR-101在犬房颤模型的心房中表达下调，且在SK3的3'-UTR区域含有miR-101的调控位点。在前期研究基础上，本项目拟通过上调和下调miR-101的表达，在培养大鼠心房肌和大鼠房颤模型中检测其对SK3表达和电流的影响，对房颤易感性的影响，以及二者是否存在直接相互作用，以从分子水平和整体动物水平探讨miR-101在房颤心房的电重构过程中的作用及其作用机制，以证实miR-101通过对SK3的直接调控作用参与房颤心房的电重构过程。该研究在完善和补充对房颤发生机制的认识，为microRNA靶向作用机制研究提供新的思路，也为房颤治疗提供新的靶点。

心房颤动存在有心脏的电重构，心房电重构在房颤的发生和维持中起着重要作用，microRNA 可能是房颤发生和维持机制中的新的潜在靶点。miR-101被发现在犬房颤模型中表达下调，但其作用机制有待研究。在本项目研究中发现，miR-101在持续性房颤患者心房肌中的表达较窦性心律者明显降低，而预测的其靶基因SK3和CACNB2在持续性房颤患者心房肌中mRNA水平和蛋白水平都升高。荧光素酶活性检测发现miR-101可直接作用于SK3和CACNB2的3’-UTR。下调和上调miR-101表达可使SK3和CACNB2的表达分别升高和降低。下调miR-101表达可增加L型钙电流并延长动作电位时程，在体检测大鼠房颤易感性也发现miR-101表达下调可减少快速起搏房颤以及房颤诱发的早搏的发生率。以上结果表明miR-101参与房颤的电重构过程，但其在房颤发生过程中表达下调而起拮抗性的保护作用。这一发现对于我们从新的角度认识microRNA在房颤发生中的作用以及完善和补充房颤发生机制的认识具有重要意义。