Zhu Hongjun, Wang Hegui, Zhang Xiwen, Hou Xiaofeng, Cao Kejiang, Zou Jiangang
Department of Cardiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
J Biomed Res. 2010 Jul;24(4):292-300. doi: 10.1016/S1674-8301(10)60041-3.
To evaluate the arrhythmogenic effects of dismantling cadherin-mediated adhesion by recombinant mouse aminopeptidase N (rmAPN) in murine hearts.
rmAPN was incubated with cultured neonatal rat cardiomyocytes as well as being infused in adult mice. The cell-cell connections were immunolabelled and observed by laser confocal microscopy. Disruption of the N-terminal of N-cadherin (N-cad) was detected by western blot and quantitative immunofluorescence. The risk of inducible ventricular tachyarrhythmia was evaluated in mice by an electrophysiological study.
Disrupted cell-cell contact was observed in cultured neonatal rat cardiomyocytes in response to 30-40 ng/µL rmAPN. Loss of the N-terminal in N-cad and altered distribution of connexin 43 (Cx43) were observed in hearts from rmAPN-infused mice. In addition, a reduction of phosphorylated Cx43 was also detected concomitant with redistribution of Cx43. Electrophysiological studies of rmAPN-infused mice showed prolonged QRS duration and increased inducibility of ventricular tachycardias.
Disruption of N-cad by rmAPN contributes to gap junction remodeling and may elicit arrhythmogenic effects. The disorder of adherent junctions by proteolytic enzymes may play an important role in arrhythmogenic mechanisms in correlated diseases.
评估重组小鼠氨肽酶N（rmAPN）破坏小鼠心脏中钙黏蛋白介导的黏附作用所产生的致心律失常效应。
将rmAPN与培养的新生大鼠心肌细胞一起孵育，并注入成年小鼠体内。通过激光共聚焦显微镜对细胞间连接进行免疫标记并观察。通过蛋白质印迹法和定量免疫荧光法检测N-钙黏蛋白（N-cad）N端的破坏情况。通过电生理研究评估小鼠诱导性室性心律失常的风险。
在30 - 40 ng/µL的rmAPN作用下，培养的新生大鼠心肌细胞中观察到细胞间接触被破坏。在注入rmAPN的小鼠心脏中，观察到N-cad的N端缺失以及连接蛋白43（Cx43）分布改变。此外，还检测到Cx43磷酸化水平降低，同时伴有Cx43的重新分布。对注入rmAPN的小鼠进行电生理研究显示，QRS波时限延长，室性心动过速的诱导性增加。
rmAPN对N-cad的破坏导致缝隙连接重塑，并可能引发致心律失常效应。蛋白水解酶导致的黏附连接紊乱可能在相关疾病的心律失常机制中起重要作用。
