Chen Fangyi, Ge Zhe, Li Nan, Yu Zuochong, Wu Rongbo, Zhao Yan, He Xianwei, Cai Guoping
Department of Orthopedics, Jinshan Hospital, Fudan University, Shanghai 201508, P.R. China.
Department of Stomatology, Jinshan Hospital, Fudan University, Shanghai 201508, P.R. China.
Exp Ther Med. 2022 Jun 10;24(2):509. doi: 10.3892/etm.2022.11436. eCollection 2022 Aug.
The existence of endoplasmic reticulum (ER) stress in neurodegenerative diseases has been well established. Tauroursodeoxycholic acid (TUDCA) is a bile acid taurine conjugate derived from ursodeoxycholic acid, which has been reported to exert cytoprotective effects on several types of cells by inhibiting ER stress. The present study explored the effects of TUDCA on primary cultured rat dorsal root ganglion (DRG) neurons. Cell viability and apoptosis of DRG neurons treated with TUDCA and tunicamycin were detected by CellTiter-Blue assay and TUNEL staining, respectively. The protein levels and phosphorylation of apoptosis and ERS-related signaling pathway molecules were detected by western blot, and the mRNA levels of related genes were assessed by reverse transcription-quantitative PCR. Notably, TUDCA had no significant cytotoxic effect on DRG neurons at concentrations ≤250 µM. In addition, the apoptosis induced by tunicamycin exposure was markedly suppressed by TUDCA, as indicated by the percentage of TUNEL-positive cells, the activities of caspases and the changes in expression levels of critical apoptosis factors. Furthermore, the cytotoxicity of tunicamycin in DRG neurons was accompanied by an increase in malondialdehyde (MDA) content, reactive oxygen species (ROS) and lactate dehydrogenase (LDH) production, and a decrease in glutathione (GSH) levels. The changes in oxidative stress-related factors (ROS, LDH, MDA and GSH) were reversed by TUDCA. Furthermore, as determined by western blotting, the increase in C/EBP homologous protein, glucose-regulated protein 78 and cleaved caspase-12 expression following tunicamycin treatment suggested the activation of ER stress. Downregulation of ER stress components and unfolded protein response sensors by TUDCA confirmed the implication of ER stress in the effects of TUDCA on DRG neurons. In conclusion, the present study indicated that TUDCA may protect against tunicamycin-induced DRG apoptosis by suppressing the activation of ER stress. The protective effect and the therapeutic value of TUDCA in nervous system injury require further study in animal models.
内质网（ER）应激在神经退行性疾病中的存在已得到充分证实。牛磺熊去氧胆酸（TUDCA）是一种由熊去氧胆酸衍生而来的胆汁酸牛磺酸共轭物，据报道它通过抑制内质网应激对多种类型的细胞发挥细胞保护作用。本研究探讨了TUDCA对原代培养的大鼠背根神经节（DRG）神经元的影响。分别通过CellTiter - Blue检测法和TUNEL染色检测用TUDCA和衣霉素处理的DRG神经元的细胞活力和凋亡情况。通过蛋白质印迹法检测凋亡和内质网应激相关信号通路分子的蛋白质水平及磷酸化情况，并通过逆转录定量PCR评估相关基因的mRNA水平。值得注意的是，浓度≤250 µM的TUDCA对DRG神经元没有明显的细胞毒性作用。此外，TUDCA显著抑制了衣霉素诱导的凋亡，这通过TUNEL阳性细胞百分比、半胱天冬酶活性以及关键凋亡因子表达水平的变化得以体现。此外，衣霉素对DRG神经元的细胞毒性伴随着丙二醛（MDA）含量、活性氧（ROS）和乳酸脱氢酶（LDH）产生的增加以及谷胱甘肽（GSH）水平的降低。TUDCA逆转了氧化应激相关因子（ROS、LDH、MDA和GSH）的变化。此外，通过蛋白质印迹法测定，衣霉素处理后C/EBP同源蛋白、葡萄糖调节蛋白78和裂解的半胱天冬酶 - 12表达的增加表明内质网应激被激活。TUDCA对内质网应激成分和未折叠蛋白反应传感器的下调证实了内质网应激在TUDCA对DRG神经元作用中的影响。总之，本研究表明TUDCA可能通过抑制内质网应激的激活来保护DRG神经元免受衣霉素诱导的凋亡。TUDCA在神经系统损伤中的保护作用和治疗价值需要在动物模型中进一步研究。
