CircFKBP3 absence alleviates oxygen glucose deprivation-induced function loss of human brain microvascular endothelial cells <i>in vitro</i> via governing the miR-766-3p/TRAF3 axis

Brain microvascular endothelial cell (BMEC) functions loss is a key event in the development of ischemic stroke, which may be affected by the dysregulation of circular RNAs (circRNAs). We aimed to unveil the role of circRNA FKBP Prolyl Isomerase 3 (circFKBP3) in cell models of ischemic stroke. Cell models of ischemic stroke were constructed in human BEMCs (HBMECs) with the treatment of oxygen glucose deprivation (OGD). Quantitative real-time PCR (qPCR) and western blotting were conducted for expression analysis of circFKBP3, miR-766-3p and TNF receptor associated factor 3 (TRAF3). CCK-8, transwell, wound healing, flow cytometry, tube formation and ELISA assays were implemented to monitor cell viability, migration, apoptosis, angiogenesis and inflammation production. The putative binding relationship between miR-766-3p and circFKBP3 or TRAF3 was validated by dual-luciferase, RIP and pull-down assays. CircFKBP3 expression was elevated in OGD-treated HBMECs. OGD suppressed HBMEC viability, migration, angiogenesis, and provoked cell apoptosis and inflammation production, while knockdown of circFKBP3 attenuated these effects. CircFKBP3 interacted with miR-766-3p, and circFKBP3 absence-repressed HBMEC function loss and inflammation were recovered by miR-766-3p inhibition. CircFKBP3 targeted miR-766-3p to regulate TRAF3 expression. MiR-766-3p enrichment-repressed HBMEC function loss and inflammation were recovered by TRAF3 overexpression. CircFKBP3 absence alleviated OGD-induced function loss and inflammatory responses of HBMECs <i>via</i> governing the miR-766-3p/TRAF3 axis. CircFKBP3 expression is elevated in OGD-treated HBMECs. OGD-induced HBMEC function loss and inflammation are alleviated by circFKBP3 absence. CircFKBP3 directly targets miR-766-3p to regulate TRAF3 expression.脑微血管内皮细胞（brain microvascular endothelial cell, BMEC）功能丧失是缺血性脑卒中发生发展中的关键事件，其可能受环状RNA（circular RNAs, circRNAs）表达失调的影响。本研究旨在揭示环状RNA FKBP脯氨酰异构酶3（circRNA FKBP Prolyl Isomerase 3, circFKBP3）在缺血性脑卒中细胞模型中的作用。采用氧糖剥夺（oxygen glucose deprivation, OGD）处理人BMECs（HBMECs）构建缺血性脑卒中细胞模型。通过实时定量聚合酶链反应（quantitative real-time PCR, qPCR）与蛋白质印迹（western blotting）分析circFKBP3、miR-766-3p及肿瘤坏死因子受体相关因子3（TNF receptor associated factor 3, TRAF3）的表达水平。采用CCK-8、Transwell、划痕愈合实验、流式细胞术、管形成实验与酶联免疫吸附测定（enzyme-linked immunosorbent assay, ELISA）分别检测细胞活力、迁移能力、凋亡情况、血管生成能力与炎症因子产生水平。通过双荧光素酶报告基因实验、RNA免疫沉淀（RNA immunoprecipitation, RIP）与下拉实验验证miR-766-3p与circFKBP3或TRAF3之间的潜在结合关系。经OGD处理的HBMECs中circFKBP3表达上调。OGD可抑制HBMEC的活力、迁移与血管生成能力，并诱导细胞凋亡与炎症因子产生，而敲低circFKBP3可缓解上述效应。circFKBP3可与miR-766-3p相互结合，且circFKBP3敲低所抑制的HBMEC功能丧失与炎症反应可被miR-766-3p抑制剂逆转。circFKBP3通过靶向miR-766-3p调控TRAF3的表达。miR-766-3p过表达所抑制的HBMEC功能丧失与炎症反应可被TRAF3过表达逆转。circFKBP3敲低通过调控miR-766-3p/TRAF3轴缓解OGD诱导的HBMEC功能丧失与炎症应答。