老年性窦房结功能减退新机制：miR-125的调控作用及防治新靶点研究

老年性窦房结功能减退与心血管疾病严重程度和死亡率明显相关而日益受到重视。探索其发病机制并改善窦房结功能是目前缓慢性心律失常领域研究的热点和难点。研究发现，老年性窦房结功能减退的过程是窦房结起搏相关基因及其离子通道重塑的过程。而内源性的、非编码单链miR-125 异常增高并多靶点负向调控起搏相关基因及其离子通道。因而提出假说：miR-125多靶点负向调控起搏相关基因及其离子通道是老年性窦房结功能减退的关键机制，miR-125反义寡核苷酸可多靶标改善离子通道重塑而使窦房结恢复完整起搏电流谱，进而改善窦房结功能。本研究设立幼年组、中年组+miR-125和老年组+AMO-125,通过窦房结电生理参数测定、RT-PCR、western blotting及单细胞膜片钳技术，探索miR125在老年性窦房结功能减退中的作用和涉及到的离子通道途径，以及AMO-125防治老年性窦房结功能减退的有效性和安全性。

It is known that age-dependent degeneration of sinoatrial node (SAN)function is strong associated with the mortality and severity of cardiovascular diseases,which has been attracted more attentions.Understanding the mechanisms of the age-dependent degeneration of SAN function and find new approaches for bradyarrhythmias therapy has become a hot spot and difficulty.Previous studies indicated that age-dependent degeneration of SAN function may occur as a result of changes of pacemaker genes and the remodeling of ions channels, which provide a novel strategy for prevent this disease.Previous studies and the predictions of bioinformatics tools had been suggested that an endogenous noncodin，single-stranded miR-125 overexpressed and could negatively modulate genes and ion channels that related pacing. Base on aforementioned studis, we hypothesized that the fundmental mechanisms of SAN function decline may be miR-125 mediate post-transcriptional repressing multi-target mRNA that related pacemaker gene and adverse the remodeling of ion channels with SAN aging.A miR-125 inhibitor,2-O-methyl-modified antisense oligoribonucleotides(AMOs) could relieved the adverse remodeling of ion channels,recovery the paceaker currents lineage and improved the SAN function by the multi-targeting. Thus, miR-125 may is a novel antiarrhythmic target for prevented the age-dependent degeneration of SAN.In this study, we will established two experimental groups to investigate the mechanisms of age-dependet degeneration of SAN function,that is:childhood and middle age groups that will be intervented with miR-125,another is old group that will be intervented with AMO-125.The role of miR-125 and the ion channels genes that related miR-125 in age-dependent degneration of SAN function will be investigated by miR-125 and AMO-125 gene transfer,recording the electrophysiologic parameters of the SAN, RT-PCR,western blotting and single-cell patch-clamp recording.Meanwhile,the effectivity and the safety of AMO-125 for treatment of age-dependent degeneration of SAN funcyion will be elaluated.This study will provide the new insights for understanding the mechanisms of the the age-dependent degeneration of SAN function and new approach for bradyarrhythmias therapy.