Enhanced endoplasmic reticulum SERCA activity by overexpression of hepatic stimulator substance gene prevents hepatic cells from ER stress-induced apoptosis
Enhanced endoplasmic reticulum SERCA activity by overexpression of hepatic stimulator substance gene prevents hepatic cells from ER stress-induced apoptosis
复制标题
通过肝刺激物质基因的过度表达增强内质网SERCA活性，防止肝细胞内质网应激诱导的细胞凋亡。
DOI：
10.1152/ajpcell.00117.2013
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发表时间：
2014-02-01
影响因子：
5.5
通讯作者：
An, Wei
中科院分区：
文献类型：
--
作者：
Zhang, Jing;Li, Yuan;An, Wei
虽然非酒精性脂肪性肝病（NAFLD）的潜在发病机制尚不清楚，但越来越多的证据表明内质网（ER）应激可能将游离脂肪酸与NAFLD联系起来。由于我们以前报道过肝刺激物质（HSS）可以保护肝脏免受脂肪变性，本研究旨在研究HSS的保护作用是否与其抑制ER应激有关。HSS基因可稳定转染BEL-7402肝癌细胞，并在ER中有效表达。棕榈酸（PA）诱导的肝细胞脂毒性在HSS转染的细胞中再现，HSS缓解ER应激和细胞凋亡随后进行了检查。结果表明，PA处理导致细胞内脂肪酸的大量积累和活性氧（ROS）的显着增加。与野生型或突变型HSS转染细胞相比，表达HSS的细胞中ROS的产生受到抑制，ER应激相关标志物葡萄糖调节蛋白78（GRP-78）、固醇调节元件结合蛋白（SREBP）、抗磷酸化类ER激酶（p-PERK）、抗磷酸化真核起始因子2α（p-eIF 2 α）和抗C/EBP同源蛋白（CHOP）表达下调。此外，PA处理严重损害肌内质网Ca（2+）-ATP酶（SERCA）的活性，导致ER应激期间钙稳态失衡，这可以在HSS转染细胞中得到挽救。HSS对SERCA的保护作用与两种典型的自由基清除剂N-乙酰基-L-半胱氨酸（NAC）和二巯基丙磺酸钠（Na-DMPS）相同。因此，在HSS表达细胞中ER应激介导的凋亡率显著降低。总之，HSS对ER应激的保护作用可能与清除ROS以恢复SERCA的活性有关。
Although the potential pathogenesis of nonalcoholic fatty liver disease (NAFLD) is unclear, increasing evidence indicates that endoplasmic reticulum (ER) stress may link free fatty acids to NAFLD. Since we previously reported that hepatic stimulator substance (HSS) could protect the liver from steatosis, this study is aimed to investigate whether HSS protection could be related with its inhibition on ER stress. The HSS gene was stably transfected into BEL-7402 hepatoma cells and effectively expressed in ER. The palmitic acid (PA)-induced heptocyte lipotoxicity was reproduced in the HSS-transfected cells, and HSS alleviation of the ER stress and apoptosis were subsequently examined. The results showed that PA treatment led to a heavy accumulation of fatty acids within the cells and a remarkable increase in reactive oxygen species (ROS). However, in the HSS-expressing cells, production of ROS was inhibited and ER stress-related marker glucose-regulated protein 78 (GRP-78), sterol regulatory element-binding protein (SREBP), anti-phospho-PRK-1ike ER kinase (p-PERK), anti-phospho-eukaryotic initiation factor 2α (p-eIF2α), and anti-C/EBP homologous protein (CHOP) were downregulated compared with the wild-type or mutant HSS-transfected cells. Furthermore, PA treatment severely impaired the activity of sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA), leading to imbalanced calcium homeostasis during ER stress, which could be rescued in the HSS-trasfected cells. The protection provided by HSS to the SERCA is identical to that observed with N-acetyl-l-cysteine (NAC) and sodium dimercaptopropane sulfonate (Na-DMPS), which are two typical free radical scavengers. As a consequence, the rate of ER stress-mediated apoptosis in the HSS-expressing cells was significantly reduced. In conclusion, the protective effect of HSS against ER stress may be associated with the removal of ROS to restore the activity of the SERCA.