ERK1/2 Signaling Pathway in the Release of VEGF from Muller Cells in Diabetes

作者:Ye Xiaofeng; Ren Hui; Zhang Meng; Sun Zhongcui; Jiang Alice C; Xu Gezhi*
来源:Investigative Ophthalmology & Visual Science, 2012, 53(7): 3481-3489.
DOI:10.1167/iovs.11-9076

摘要

PURPOSE. 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 Muller 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 Muller cells. Muller 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 Muller cells early in diabetes. In vitro high glucose stimulation of Muller 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 Muller cells secretion of VEGF under high glucose conditions. CONCLUSIONS. ERK1/2 signaling pathway has some role in regulating Muller cells secretion of VEGF in DR. Targeting the ERK1/2 signaling pathway in Muller 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. (Invest Ophthalmol Vis Sci. 2012;53:3481-3489) DOI:10.1167/iovs.11-9076