Zhong Yujie, Jin Chengni, Han Jiahui, Zhu Jiachang, Liu Qi, Sun Dianjun, Xia Xiaodong, Peng Xiaoli
College of Food Science and Engineering, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Cell Biol Toxicol. 2021 Oct;37(5):795-809. doi: 10.1007/s10565-021-09589-x. Epub 2021 Mar 2.
3-Chloro-1, 2-propanediol (3-MCPD) is a food-borne toxic substance well-known for more than 40 years that is mainly associated with nephrotoxicity. A better understanding of 3-MCPD nephrotoxicity is required to devise efficacious strategies to counteract its toxicity. In the present work, the role of endoplasmic reticulum (ER) stress along with its underlying regulatory mechanism in 3-MCPD-mediated renal cytotoxicity was investigated in vivo and in vitro. Our data indicated that 3-MCPD-stimulated ER stress response evidenced by sustained activation of PERK-ATF4-p-CHOP and IRE1 branches in Sprague Dawley (SD) rats and human embryonic kidney (HEK293) cells. Moreover, ER stress-associated specific apoptotic initiator, caspase 12, was over-expressed. Blocking ER stress with its antagonist, 4-phenylbutyric acid (4-PBA), improved the morphology and function of kidney effectively. 4-PBA also increased cell viability, relieved mitochondrial vacuolation, and inhibited cell apoptosis through regulating caspase-dependent intrinsic apoptosis pathways. Furthermore, the enhanced expressions of two mitochondrial fission proteins, DRP1/p-DRP1 and FIS1, and the relocation of DRP1 on mitochondria subjected to 3-MPCD were reversed by 4-PBA, while the expression of the fusion protein, MFN2, was restored. Moreover, cellular Ca overload, the over-expression of CaMKK2, and the loss of mitochondria-associated membranes (MAM) were also relieved after 4-PBA co-treatment. Collectively, our data emphasized that ER stress plays critical role in 3-MCPD-mediated mitochondrial dysfunction and subsequent apoptosis as well as blockage of ER stress ameliorated kidney injury through improving mitochondrial fission/fusion and Ca homeostasis. These findings provide a novel insight into the regulatory role of ER stress in 3-MCPD-associated nephropathy and a potential therapeutic strategy. Graphical Headlights 1. 4-PBA inhibits ER stress mainly through regulating PERK-ATF4-CHOP and IRE1-XBP1s branches. 2. Inhibition of ER stress by 4-PBA mitigates ER associated and mitochondrial apoptosis 3. Inhibition of ER stress by 4-PBA helps maintaining calcium homeostasis and mitochondrial dynamic.
3-氯-1,2-丙二醇（3-MCPD）是一种已为人熟知40多年的食源性有毒物质，主要与肾毒性有关。为了制定有效的策略来对抗其毒性，需要更好地了解3-MCPD的肾毒性。在本研究中，我们在体内和体外研究了内质网（ER）应激在3-MCPD介导的肾细胞毒性中的作用及其潜在的调控机制。我们的数据表明，在Sprague Dawley（SD）大鼠和人胚肾（HEK293）细胞中，3-MCPD刺激的ER应激反应表现为PERK-ATF4-p-CHOP和IRE1分支的持续激活。此外，ER应激相关的特异性凋亡启动因子caspase 12过表达。用其拮抗剂4-苯基丁酸（4-PBA）阻断ER应激可有效改善肾脏的形态和功能。4-PBA还通过调节caspase依赖性内源性凋亡途径增加细胞活力、减轻线粒体空泡化并抑制细胞凋亡。此外，4-PBA可逆转3-MPCD作用下两种线粒体分裂蛋白DRP1/p-DRP1和FIS1的表达增强以及DRP1在线粒体上的重新定位，同时恢复融合蛋白MFN2的表达。此外，4-PBA共同处理后，细胞内钙超载、CaMKK2的过表达以及线粒体相关膜（MAM）的丧失也得到缓解。总的来说，我们的数据强调ER应激在3-MCPD介导的线粒体功能障碍及随后的细胞凋亡中起关键作用，并且阻断ER应激可通过改善线粒体分裂/融合和钙稳态来减轻肾损伤。这些发现为ER应激在3-MCPD相关性肾病中的调控作用提供了新的见解以及一种潜在的治疗策略。图1. 4-PBA主要通过调节PERK-ATF4-CHOP和IRE1-XBP1s分支来抑制ER应激。2. 4-PBA对ER应激的抑制减轻了ER相关和线粒体凋亡。3. 4-PBA对ER应激的抑制有助于维持钙稳态和线粒体动态平衡。
