title: ERK1/2 signaling pathway in the release of VEGF from Müller cells in diabetes.
abstract: OBJECTIVE
  Diabetic retinopathy (DR) is one of the most serious complications of diabetes and has become a major blinding eye disease, but its treatment remains unsatisfactory. The ERK1/2 signaling pathway has been shown to participate in regulating secretion of VEGF in DR from our previous studies. The role of VEGF in the development of DR provides a target for treatment. Our present research focuses on Müller cells, a major source of VEGF secretion, to investigate the role of ERK1/2 signaling pathway on regulation of VEGF release in diabetes.
  
  
  METHODS
  Immunofluorescence was used to observe the ERK1/2 phosphorylation activity on early diabetic rat retinal Müller cells. Müller cells were stimulated by high glucose in vitro. Western blot and immunohistochemistry were used to determine ERK1/2 signaling pathway expression and phosphorylation. AP-1 DNA binding activity status was monitored by electrophoretic mobility shift assay (EMSA). ELISA and PCR monitored VEGF secretion. Inhibition of ERK1/2 phosphorylation with U0126 was observed for changes in VEGF secretion.
  
  
  RESULTS
  Phos-ERK1/2 was expressed on Müller cells early in diabetes. In vitro high glucose stimulation of Müller cells increased VEGF secretion with a peak at 24 hours. An ERK1/2 specific inhibitor, U0126, stopped the phosphorylation of ERK1/2, lowered AP-1 DNA binding activity, and reduced Müller cells secretion of VEGF under high glucose conditions.
  
  
  CONCLUSIONS
  ERK1/2 signaling pathway has some role in regulating Müller cells secretion of VEGF in DR. Targeting the ERK1/2 signaling pathway in Müller cells through intervention of the upstream signaling pathway or nuclear transcription factors of VEGF secretion could be a type of anti-VEGF treatment for DR.
authors.affiliation: EENT Hospital, Eye Institute, Fudan University, Shanghai, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Ye
authors.forename: Hui
authors.initials: H
authors.lastname: Ren
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.forename: Zhongcui
authors.initials: Z
authors.lastname: Sun
authors.forename: Alice C
authors.initials: AC
authors.lastname: Jiang
authors.forename: Gezhi
authors.initials: G
authors.lastname: Xu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D005947:Glucose / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D018808:Transcription Factor AP-1 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; D018808:Transcription Factor AP-1; C113580:U 0126; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D005947:Glucose