Laboratory Animal Center, Dalian Medical University, Dalian 116044, China; Central Laboratory, the First Affiliated Hospital, Dalian Medical University, Dalian 116011, China.
Laboratory Animal Center, Dalian Medical University, Dalian 116044, China.
Pharmacol Res. 2017 Sep;123:73-82. doi: 10.1016/j.phrs.2017.05.030. Epub 2017 Jun 24.
Defective expression of NAD-dependent protein deacetylase sirtuin 1 (SIRT1) triggers endoplasmic reticulum (ER) stress and epithelial cell apoptosis in inflammatory bowel disease. MicroRNA-132 (miR-132) has been shown to regulate inflammatory processes through down-regulating SIRT1. Catalpol is a potential antioxidant and anti-apoptotic agent in inflammatory disease. This study aimed to investigate the signaling mechanisms underlying catalpol-induced SIRT1 activation and inhibition of ER stress in a rat colitis model. Colitis was established by intracolonic administration of 2, 4, 6-trinitrobenzene sulfonic acid. miR-132 expression was measured by quantitative real-time polymerase chain reaction and in situ hybridization, and the regulation of SIRT1 by miR-132 was examined by dual luciferase reporter assay. Protein expression related to ER stress and apoptosis was measured by western blotting. The ER stress marker proteins ATF6, CHOP, and caspase12, and acetylation of heat-shock factor-1 were increased in colitis and these increases were significantly reversed by catalpol, while the colitis-induced reduction in GRP78 was also reversed by catalpol. The inhibition of ER stress by catalpol was significantly inhibited by small interfering RNA targeting SIRT1 or miR-132. Moreover, other colitis symptoms including infiltration of inflammatory cells, cytokine profiles, oxidative responses, and epithelial cell apoptosis were also significantly decreased by catalpol. Mechanistically, the defective expression of SIRT1 in colitis was significantly counteracted by catalpol, while miR-132, which is a negative targeting regulator of SIRT1, was confirmed as the potential target of catalpol. These results support a link between ER stress and the miR-132/SIRT1/heat-shock factor-1 signaling pathway, and the modulation of this pathway by catalpol in colitis.
NAD 依赖性蛋白去乙酰化酶 SIRT1（SIRT1）表达缺陷可引发炎症性肠病中的内质网（ER）应激和上皮细胞凋亡。miR-132（miR-132）已被证明可通过下调 SIRT1 来调节炎症过程。梓醇是炎症性疾病中潜在的抗氧化和抗凋亡剂。本研究旨在探讨梓醇诱导 SIRT1 激活和抑制大鼠结肠炎模型中 ER 应激的信号机制。通过结肠内给予 2,4,6-三硝基苯磺酸建立结肠炎。通过定量实时聚合酶链反应和原位杂交测量 miR-132 的表达，并通过双荧光素酶报告基因测定检查 miR-132 对 SIRT1 的调节。通过 Western blot 测量与 ER 应激和细胞凋亡相关的蛋白表达。在结肠炎中，ER 应激标志物蛋白 ATF6、CHOP 和 caspase12 以及热休克因子-1 的乙酰化增加，而梓醇显著逆转了这些增加，同时，GRP78 的减少也被梓醇逆转。通过针对 SIRT1 或 miR-132 的小干扰 RNA 显著抑制了梓醇对 ER 应激的抑制。此外，梓醇还显著降低了其他结肠炎症状，包括炎症细胞浸润、细胞因子谱、氧化反应和上皮细胞凋亡。从机制上讲，梓醇显著逆转了 SIRT1 在结肠炎中的缺陷表达，而 miR-132 是 SIRT1 的负靶向调节剂，被确认为梓醇的潜在靶标。这些结果支持 ER 应激与 miR-132/SIRT1/热休克因子-1 信号通路之间的联系，以及梓醇在结肠炎中对该通路的调节。
