Transcription factors regulate GPR91-mediated expression of VEGF in hypoxia-induced retinopathy
Transcription factors regulate GPR91-mediated expression of VEGF in hypoxia-induced retinopathy
复制标题
转录因子在缺氧诱导的视网膜病变中调节 GPR91 介导的 VEGF 表达
DOI：
10.1038/srep45807
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发表时间：
2017-04-04
影响因子：
4.6
通讯作者：
Wu, Qiang
中科院分区：
文献类型：
--
作者：
Li, Tingting;Hu, Jianyan;Wu, Qiang
缺氧是糖尿病视网膜病变(DR)发病机制中最重要的因素。我们以前的研究证明G蛋白偶联受体91(GPR91)参与了DR血管内皮生长因子(VEGF)分泌的调节。本研究建立了新生大鼠50%和12%氧气交替暴露24小时14天的OIR模型。GPR91shRNA治疗可减轻视网膜无血管面积、异常新生血管和周细胞丢失。Western印迹和qRT-PCR结果显示，CoCl2暴露可促进VEGF的表达和分泌，激活ERK1/2信号通路，上调C/EBP和AP-1的表达。GPR91基因敲除可抑制ERK1/2活性。GPR91siRNA转导和ERK1/2抑制剂U0126抑制C/eBPβ、C/eBPδ、c-Fos和HIF-1α的表达。荧光素酶报告分析和染色质免疫沉淀(ChIP)分析表明，C/eBPβ和c-Fos结合了血管内皮生长因子启动子区域的功能转录因子结合部位，但不与C/eBPδ结合。RNA干扰下调C/EBPβ和c-Fos基因可降低血管内皮细胞生长因子的表达。我们的结果提示，GPR91ERK1/2-C/EBPβ(c-Fos，HIF-1α)信号通路的激活在调节大鼠视网膜神经节细胞血管内皮生长因子的转录中起着紧张性的作用。
Hypoxia is the most important factor in the pathogenesis of diabetic retinopathy (DR). Our previous studies demonstrated that G protein-coupled receptor 91(GPR91) participated in the regulation of vascular endothelial growth factor (VEGF) secretion in DR. The present study induced OIR model in newborn rats using exposure to alternating 24-hour episodes of 50% and 12% oxygen for 14 days. Treatment with GPR91 shRNA attenuated the retinal avascular area, abnormal neovascularization and pericyte loss. Western blot and qRT-PCR demonstrated that CoCl2exposure promoted VEGF expression and secretion, activated the ERK1/2 signaling pathways and upregulated C/EBP and AP-1. Knockdown of GPR91 inhibited ERK1/2 activity. GPR91 siRNA transduction and the ERK1/2 inhibitor U0126 inhibited the increases in C/EBP β, C/EBP δ, c-Fos and HIF-1α. Luciferase reporter assays and a chromatin immunoprecipitation (ChIP) assay demonstrated that C/EBP β and c-Fos bound the functional transcriptional factor binding site in the region of the VEGF promoter, but not C/EBP δ. Knockdown of C/EBP β and c-Fos using RNAi reduced VEGF expression. Our data suggest that activation of the GPR91-ERK1/2-C/EBP β (c-Fos, HIF-1α) signaling pathway plays a tonic role in regulating VEGF transcription in rat retinal ganglion cells.