Wu Yaqin, Zhao Dan, Zhuang Jiabao, Zhang Fuqiang, Xu Chun
Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China.
PLoS One. 2016 Dec 12;11(12):e0168268. doi: 10.1371/journal.pone.0168268. eCollection 2016.
Human periodontal ligament (PDL) cells underwent apoptosis after mechanical stretch loading. However, the exact signalling pathway remains unknown. This study aimed to elucidate how the apoptotic caspases functioned in the cyclic stretch-induced apoptosis in human PDL cells.
In the present study, 20% cyclic stretch was selected to load the cells for 6 or 24 h. The following parameters were analyzed: apoptotic rates, the protein levels of caspase-3, -7, -8 and -9 and the activities of caspase-8 and -9. Subsequently, the influences of caspase-8 and caspase-9 inhibitors on the apoptotic rate and the protein level of the activated caspase-3 were assessed as well.
The apoptotic rates increased in response to cyclic stretch, but the cells entered different apoptotic stages after 6 and 24 h stretches. Caspase-3, -7, -8 and -9 were all activated after stretch loading. The stretch-induced apoptosis and the protein level of the activated caspase-3 were inhibited after inhibiting both caspase-8 and caspase-9 in both 6 and 24 h stretched cells and after inhibiting caspase-9 in 24 h stretched cells.
Caspase-8 and -9 functioned differently at different apoptotic stages in human PDL cells after cyclic stretch.
机械拉伸加载后人牙周膜（PDL）细胞会发生凋亡。然而，确切的信号通路仍不清楚。本研究旨在阐明凋亡半胱天冬酶在人PDL细胞周期性拉伸诱导的凋亡中是如何发挥作用的。
在本研究中，选择20%的周期性拉伸对细胞加载6小时或24小时。分析以下参数：凋亡率、半胱天冬酶-3、-7、-8和-9的蛋白水平以及半胱天冬酶-8和-9的活性。随后，还评估了半胱天冬酶-8和半胱天冬酶-9抑制剂对凋亡率和活化半胱天冬酶-3蛋白水平的影响。
周期性拉伸后凋亡率增加，但细胞在拉伸6小时和24小时后进入不同的凋亡阶段。拉伸加载后半胱天冬酶-3、-7、-8和-9均被激活。在6小时和24小时拉伸的细胞中同时抑制半胱天冬酶-8和半胱天冬酶-9以及在24小时拉伸的细胞中抑制半胱天冬酶-9后，拉伸诱导的凋亡和活化半胱天冬酶-3的蛋白水平均受到抑制。
在人PDL细胞周期性拉伸后的不同凋亡阶段，半胱天冬酶-8和-9发挥不同的作用。
