Activation of TGR5 protects blood brain barrier via the BRCA1/Sirt1 pathway after middle cerebral artery occlusion in rats
Activation of TGR5 protects blood brain barrier via the BRCA1/Sirt1 pathway after middle cerebral artery occlusion in rats
复制标题
大脑中动脉闭塞后 TGR5 激活通过 BRCA1/Sirt1 通路保护血脑屏障
DOI：
10.1186/s12929-020-00656-9
复制
发表时间：
2020-05-08
影响因子：
11
通讯作者：
Zhang, John H.
中科院分区：
文献类型：
--
作者：
Liang, Hui;Matei, Nate;Zhang, John H.
背景血脑屏障（blood-brain barrier，BBB）的破坏在缺血性脑卒中的发病机制中起重要作用。TGR 5被认为是治疗神经系统疾病的潜在靶标。方法本研究探讨TGR 5激活在减轻大脑中动脉闭塞（MCAO）后血脑屏障损伤中的作用及其机制。对Sprague-Dawley大鼠进行MCAO模型，鼻内施用TGR 5激动剂INT 777。TGR 5和BRCA 1的小干扰RNA（siRNA）在MCAO前48 h通过侧脑室注射。观察脑体积、脑含水量、血脑屏障通透性、神经功能评分、免疫印迹、免疫荧光染色和免疫共沉淀。结果MCAO后，损伤侧大脑半球内源性TGR 5和BRCA 1表达上调，内皮细胞表达TGR 5。在缺血后24 h和72 h，用INT 777治疗可降低脑含水量和BBB通透性，减少梗死体积并改善神经功能评分。INT 777给药增加BRCA 1和Sirt 1表达，以及上调紧密连接蛋白的表达。缺血性损伤诱导的TGR 5与BRCA 1的相互作用。TGR 5 siRNA和BRCA 1 siRNA显著抑制BRCA 1和Sirt 1的表达，加重BBB通透性，加重MCAO后卒中结局。INT 777在MCAO后24 h的保护作用也被TGR 5 siRNA或BRCA 1 siRNA消除。结论激活TGR 5可通过BRCA 1/Sirt 1信号通路减少脑缺血后BBB的破坏，改善神经功能。TGR 5可能作为一个潜在的新的候选人，以减轻脑损伤后MCAO。
Background The disruption of the blood-brain barrier (BBB) plays a critical event in the pathogenesis of ischemia stroke. TGR5 is recognized as a potential target for the treatment for neurologic disorders. Methods This study investigated the roles of TGR5 activation in attenuating BBB damage and underlying mechanisms after middle cerebral artery occlusion (MCAO). Sprague-Dawley rats were subjected to model of MCAO and TGR5 agonist, INT777, was administered intranasally. Small interfering RNA (siRNA) for TGR5 and BRCA1 were administered through intracerebroventricular injection 48 h before MCAO. Infarct volumes, brain water content, BBB permeability, neurological scores, Western blot, immunofluorescence staining and co- immunoprecipitation were evaluated. Results Endogenous TGR5 and BRCA1 were upregulated in the injured hemisphere after MCAO and TGR5 expressed in endothelial cells. Treatment with INT777 alleviated brain water content and BBB permeability, reduced infarction volume and improved neurological scores at 24 h and 72 h after ischemia. INT777 administration increased BRCA1 and Sirt1 expression, as well as upregulated expressions of tight junction proteins. Ischemic damage induced interaction of TGR5 with BRCA1. TGR5 siRNA and BRCA1 siRNA significantly inhibited expressions of BRCA1 and Sirt1, aggravated BBB permeability and exacerbated stroke outcomes after MCAO. The protective effects of INT777 at 24 h after MCAO were also abolished by TGR5 siRNA or BRCA1 siRNA. Conclusions Our findings demonstrate that activating TGR5 could reduce BBB breakdown and improve neurological functions through BRCA1/Sirt1 signaling pathway after MCAO. TGR5 may serve as a potential new candidate to relieve brain injury after MCAO.