State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, China.
Cellular and Molecular Biology Center of China Pharmaceutical University, Nanjing, China.
Int J Cardiol. 2018 Nov 15;271:211-218. doi: 10.1016/j.ijcard.2018.04.079. Epub 2018 Aug 23.
Mitochondrial fission is the essential mechanisms of myocardial ischemia/reperfusion (MI/R)-induced cardiomyocytes apoptosis. Myosin II plays a key role in fission due to the recruitment and actomyosin constriction at the fission site in U2OS cells. However, the role of myosin IIA-actin interaction in regulating MI/R-induced cardiomyocytes mitochondrial fission and apoptosis remains to be fully elucidated.
When cardiomyocytes are exposed to simulated I/R injury, the myosin IIA protein translocated from the juxtamembrane to the cytoplasm, interacted with actin filaments, formed stress fibers and generated contractile forces. Treatment with the myosin II inhibitor blebbistatin attenuated the myosin IIA-actin complex induced actomyosin contractility and prevented cardiomyocytes apoptosis as reflected by inhibition of cleaved caspase-3 expression, normalization of Bcl-2/Bax levels and decreased apoptotic cells. Meanwhile, blebbistatin inhibited the activation of PINK1/Parkin pathway and ameliorated mitochondrial fission as evidenced by improvement of mitochondrial morphology, inhibition of Drp1 phosphorylation at Ser616 and translocation. Furthermore, CRISPR/Cas9 knockout of myosin IIA blocked I/R-induced apoptosis, suppressed PINK1/Parkin pathway and reduced mitochondrial fission. Importantly, blebbistatin attenuated myocardial apoptosis, inhibited myosin IIA-actin interaction and PINK1/Parkin pathway, suppressed myocardial ultrastructure abnormalities and mitochondrial fission in a mouse MI/R injury model.
Inhibition of actomyosin contractility induced by myosin IIA-actin interaction could impede myocardial apoptosis and MI/R injury via PINK1/Parkin pathway and mitochondrial fission modulation both in vitro and in vivo, which may be applicable for the development of therapies for cardiovascular diseases.
线粒体裂变是心肌缺血/再灌注（MI/R）诱导的心肌细胞凋亡的基本机制。肌球蛋白 II 在分裂中起关键作用，因为它在 U2OS 细胞的分裂部位募集和肌球蛋白收缩。然而，肌球蛋白 IIA-肌动蛋白相互作用在调节 MI/R 诱导的心肌细胞线粒体裂变和凋亡中的作用仍有待充分阐明。
当心肌细胞暴露于模拟的 I/R 损伤时，肌球蛋白 IIA 蛋白从质膜转位到细胞质，与肌动蛋白丝相互作用，形成应力纤维并产生收缩力。肌球蛋白 II 抑制剂 blebbistatin 的处理减弱了肌球蛋白 IIA-肌动蛋白复合物诱导的肌球蛋白收缩，并通过抑制裂解的 caspase-3 表达、Bcl-2/Bax 水平的正常化和减少凋亡细胞来防止心肌细胞凋亡。同时，blebbistatin 抑制了 PINK1/Parkin 途径的激活，并改善了线粒体裂变，表现为线粒体形态的改善、Drp1 在 Ser616 位点的磷酸化和易位的抑制。此外，CRISPR/Cas9 敲除肌球蛋白 IIA 阻断了 I/R 诱导的凋亡，抑制了 PINK1/Parkin 途径，并减少了线粒体裂变。重要的是，blebbistatin 在小鼠 MI/R 损伤模型中减弱了心肌细胞凋亡，抑制了肌球蛋白 IIA-肌动蛋白相互作用和 PINK1/Parkin 途径，抑制了心肌超微结构异常和线粒体裂变。
肌球蛋白 IIA-肌动蛋白相互作用诱导的肌球蛋白收缩的抑制可通过 PINK1/Parkin 途径和线粒体裂变调节来阻碍心肌细胞凋亡和 MI/R 损伤，无论是在体外还是体内，这可能适用于心血管疾病治疗的发展。
