College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009, People's Republic of China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, People's Republic of China.
Sci Rep. 2017 Apr 20;7(1):977. doi: 10.1038/s41598-017-00997-w.
The Fas/FasL signaling pathway is one of the primary apoptosis pathways, but the involvement and regulatory mechanism of this pathway by autophagy remain unclear. Here we demonstrated that cadmium (Cd) activated the Fas/FasL apoptosis pathway in rat proximal tubular (rPT) cells; this was accompanied by simultaneous activation of autophagy resulted in reduced apoptosis. In this model, we induced autophagy through RAPA and further demonstrated that autophagy protects against activation of Fas/FasL signaling and apoptosis. The antiapoptotic effect of autophagy was blocked by 3-MA, an autophagy inhibitor. The interactions between Beclin-1 and Fas, FasL, FADD, caspase-8 and BID/tBID were relatively weak, with the exception of cleaved caspase-8, indicated that minimal interactions between these proteins and Beclin-1 are involved in maintaining the balance of autophagy and apoptosis. Beclin-1 precipitated with cleaved caspase-8 in a dose-dependent mannter, and the expression was increased by siRNA against Beclin-1. These data suggested that Beclin-1-mediated autophagy impairs the expression and function of cleaved caspase-8 to protect against Cd-induced activation of apopotosis through Fas/FasL signaling pathway.
Fas/FasL 信号通路是细胞凋亡的主要通路之一，但自噬在该通路中的作用及其调控机制尚不清楚。本研究表明，镉（Cd）激活了大鼠近端肾小管（rPT）细胞中的 Fas/FasL 凋亡通路；同时激活自噬，从而减少细胞凋亡。在该模型中，我们通过 RAPA 诱导自噬，并进一步证明自噬可防止 Fas/FasL 信号的激活和细胞凋亡。自噬抑制剂 3-MA 阻断了自噬的抗凋亡作用。除了裂解的 caspase-8 外，Beclin-1 与 Fas、FasL、FADD、caspase-8 和 BID/tBID 之间的相互作用相对较弱，表明这些蛋白与 Beclin-1 之间的相互作用很少参与维持自噬和凋亡的平衡。Beclin-1 与裂解的 caspase-8 呈剂量依赖性沉淀，并且通过针对 Beclin-1 的 siRNA 表达增加。这些数据表明，Beclin-1 介导的自噬损害了裂解的 caspase-8 的表达和功能，从而通过 Fas/FasL 信号通路防止 Cd 诱导的细胞凋亡的激活。
