title: Transcription factors regulate GPR91-mediated expression of VEGF in hypoxia-induced retinopathy.
abstract: 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.
authors.affiliation: Department of Ophthalmology, the Sixth People's Hospital, Shanghai Jiaotong University, 600 Yishan Road, Shanghai 200233, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Ophthalmology, the Sixth People's Hospital, Shanghai Jiaotong University, 600 Yishan Road, Shanghai 200233, China.
authors.forename: Jianyan
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Ophthalmology, the Sixth People's Hospital, Shanghai Jiaotong University, 600 Yishan Road, Shanghai 200233, China.
authors.forename: Fengjuan
authors.initials: F
authors.lastname: Gao
authors.affiliation: Department of Ophthalmology, the Sixth People's Hospital, Shanghai Jiaotong University, 600 Yishan Road, Shanghai 200233, China.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Du
authors.affiliation: Department of Ophthalmology, the Sixth People's Hospital, Shanghai Jiaotong University, 600 Yishan Road, Shanghai 200233, China.
authors.forename: Yongdong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Ophthalmology, the Sixth People's Hospital, Shanghai Jiaotong University, 600 Yishan Road, Shanghai 200233, China.|Shanghai Key Laboratory of Diabetes Mellitus, Shanghai 200233, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wu
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002070:Butadienes / Q000008:administration & dosage; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics*; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000235:genetics; D003035:Cobalt / Q000008:administration & dosage; D003930:Diabetic Retinopathy / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D000860:Hypoxia / Q000235:genetics* / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000473:pathology; D009570:Nitriles / Q000008:administration & dosage; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D012160:Retina / Q000378:metabolism / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics*
chemical_list: D002070:Butadienes; D022782:CCAAT-Enhancer-Binding Protein-beta; C545014:Cebpb protein, rat; C497254:Cebpd protein, rat; C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009570:Nitriles; D016760:Proto-Oncogene Proteins c-fos; D043562:Receptors, G-Protein-Coupled; C523503:Sucnr1 protein, rat; C113580:U 0126; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D051743:CCAAT-Enhancer-Binding Protein-delta; D003035:Cobalt; C018021:cobaltous chloride