Zheng Dong, Wang Grace, Li Shuai, Fan Guo-Chang, Peng Tianqing
Institutes of Biology and Medical Science, Soochow University, Suzhou 215123, China; Critical Illness Research, Lawson Health Research Institute, Canada; Department of Medicine, University of Western Ontario, London, Ontario N6A 4G5, Canada; Institute of Cardiovascular Science, Soochow University, Suzhou 215008, China.
Department of Pathology, University of Western Ontario, London, Ontario N6A 4G5, Canada.
Biochim Biophys Acta. 2015 May;1852(5):882-92. doi: 10.1016/j.bbadis.2015.01.019. Epub 2015 Feb 4.
Both calpain activation and endoplasmic reticulum (ER) stress are implicated in ischemic heart injury. However, the role of calpain in ER stress remains largely elusive. This study investigated whether calpain activation causes ER stress, thereby mediating cardiomyocyte apoptosis in an in vitro model of hypoxia/re-oxygenation (H/R). In neonatal mouse cardiomyocytes and rat cardiomyocyte-like H9c2 cells, up-regulation of calpain-1 sufficiently induced ER stress, c-Jun N-terminal protein kinase1/2 (JNK1/2) activation and apoptosis. Inhibition of ER stress or JNK1/2 prevented apoptosis induced by calpain-1. In an in vitro model of H/R-induced injury in cardiomyocytes, H/R was induced by a 24-hour hypoxia followed by a 24-hour re-oxygenation. H/R activated calpain-1, induced ER stress and JNK1/2 activation, and triggered apoptosis. Inhibition of calpain and ER stress blocked JNK1/2 activation and prevented H/R-induced apoptosis. Furthermore, blockade of JNK1/2 signaling inhibited apoptosis following H/R. The role of calpain in ER stress was also demonstrated in an in vivo model of ischemia/reperfusion using transgenic mice over-expressing calpastatin. In summary, calpain-1 induces ER stress and JNK1/2 activation, thereby mediating apoptosis in cardiomyocytes. Accordingly, inhibition of calpain prevents ER stress, JNK1/2 activation and apoptosis in H/R-induced cardiomyocytes. Thus, ER stress/JNK1/2 activation may represent an important mechanism linking calpain-1 to ischemic injury.
钙蛋白酶激活和内质网（ER）应激均与缺血性心脏损伤有关。然而，钙蛋白酶在ER应激中的作用仍 largely 不清楚。本研究调查了在缺氧/复氧（H/R）体外模型中，钙蛋白酶激活是否会导致ER应激，从而介导心肌细胞凋亡。在新生小鼠心肌细胞和大鼠心肌样H9c2细胞中，钙蛋白酶-1的上调充分诱导了ER应激、c-Jun氨基末端蛋白激酶1/2（JNK1/2）激活和凋亡。抑制ER应激或JNK1/2可预防钙蛋白酶-1诱导的凋亡。在心肌细胞H/R诱导损伤的体外模型中，通过24小时缺氧后再进行24小时复氧来诱导H/R。H/R激活了钙蛋白酶-1，诱导了ER应激和JNK1/2激活，并引发了凋亡。抑制钙蛋白酶和ER应激可阻断JNK1/2激活并预防H/R诱导的凋亡。此外，阻断JNK1/2信号传导可抑制H/R后的凋亡。在使用过表达钙蛋白酶抑制蛋白的转基因小鼠的缺血/再灌注体内模型中，也证明了钙蛋白酶在ER应激中的作用。总之，钙蛋白酶-1诱导ER应激和JNK1/2激活，从而介导心肌细胞凋亡。因此，抑制钙蛋白酶可预防H/R诱导的心肌细胞中的ER应激、JNK1/2激活和凋亡。因此，ER应激/JNK1/2激活可能是将钙蛋白酶-1与缺血性损伤联系起来的重要机制。
