Zhang Kai, Ding Wei, Sun Wei, Sun Xiao-jiang, Xie You-zhuan, Zhao Chang-qing, Zhao Jie
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.
Jiangsu Jiangyin People' Hospital, Jiangyin, People's Republic of China.
Apoptosis. 2016 Jan;21(1):13-24. doi: 10.1007/s10495-015-1180-7.
Low back pain is associated with intervertebral disc degeneration (IVDD) due to cellular loss through apoptosis. Mechanical factors play an important role in maintaining the survival of the annulus fibrosus (AF) cells and the deposition of extracellular matrix. However, the mechanisms that excessive mechanical forces lead to AF cell apoptosis are not clear. The present study was to look for how AF cells sense mechanical changes. In vivo experiments, the involvement of mechanoreceptors in apoptosis was examined by RT-PCR and/or immunoblotting in the lumbar spine of rats subjected to unbalanced dynamic and static forces. In vitro experiments, we investigated apoptotic signaling pathways in untransfected and transfected AF cells with the lentivirus vector for rat β1 integrin overexpression after cyclic stretch. Apoptosis in AF cells was assessed using flow cytometry, Hoechst 33258 nuclear staining. Western blotting was used to analyze expression of β1 integrin and caspase-3 and ERK1/2 MAPK signaling molecules. In the rat IVDD model, unbalanced dynamic and static forces induced apoptosis of disc cells, which corresponded to decreased expression of β1 integrin. Cyclic stretch-induced apoptosis in rat AF cells correlated with the activation of caspase-3 and with decreased levels of β1 integrin and the phosphorylation levels of ERK1/2 activation level. However, the overexpression of β1 integrin in AF cells ameliorated cyclic stretch-induced apoptosis and decreased caspase-3 activation. Furthermore, ERK1/2-specific inhibitor promotes apoptosis in vector β1-infected AF cells. These results suggest that the disruption of β1 integrin signaling may underlie disc cell apoptosis induced by mechanical stress. Further work is necessary to fully elucidate the pathophysiological mechanisms that underlie IVDD caused by unbalanced dynamic and static forces.
下背痛与椎间盘退变（IVDD）相关，这是由于细胞通过凋亡而丧失。机械因素在维持纤维环（AF）细胞存活和细胞外基质沉积方面起着重要作用。然而，过度机械力导致AF细胞凋亡的机制尚不清楚。本研究旨在探寻AF细胞如何感知机械变化。在体内实验中，通过RT-PCR和/或免疫印迹法，在承受不平衡动态和静态力的大鼠腰椎中检测机械感受器在凋亡中的作用。在体外实验中，我们研究了在循环拉伸后，未转染和用大鼠β1整合素过表达慢病毒载体转染的AF细胞中的凋亡信号通路。使用流式细胞术、Hoechst 33258核染色评估AF细胞中的凋亡。采用蛋白质印迹法分析β1整合素、半胱天冬酶-3和ERK1/2丝裂原活化蛋白激酶信号分子的表达。在大鼠IVDD模型中，不平衡的动态和静态力诱导椎间盘细胞凋亡，这与β1整合素表达降低相对应。循环拉伸诱导的大鼠AF细胞凋亡与半胱天冬酶-3的激活以及β1整合素水平降低和ERK1/2激活水平的磷酸化水平相关。然而，AF细胞中β1整合素的过表达改善了循环拉伸诱导的凋亡并降低了半胱天冬酶-3的激活。此外，ERK1/2特异性抑制剂促进载体β1感染的AF细胞凋亡。这些结果表明，β1整合素信号的破坏可能是机械应力诱导椎间盘细胞凋亡的基础。有必要进一步开展工作，以充分阐明由不平衡动态和静态力引起的IVDD的病理生理机制。
