Light Induces VEGF Gene Expression through Sp1-binding Sites in Retinoblastoma Y79 Cells

Abstract

Abstract: : Purpose: Vascular endothelial growth factor (VEGF) is an angiogenic peptide, which has been implicated in many retinopathies. Although retinal tissues are closely related to light, the role of light stimulation in the pathogenesis of retinal disease remains elusive. In this study, we investigated the effects of light on the VEGF gene expression in retinoblastoma Y79 cells. Methods:Total RNA prepared from Y79 cells stimulated with or without light was subjected to Northern blot analyses. Reporter constructs consisting of VEGF promoter / luciferase gene were transfected into Y79 cells. Nuclear factors binding to the VEGF promoter were analyzed by electrophoretic mobility shift assays (EMSAs). Results: The levels of VEGF transcripts were increased by light in a time-dependent manner. Progressive deletion and site-specific mutation analyses indicated that light stimulation increased VEGF promoter activity through G+C-rich sequence which is proved as Sp1-binding sites by supershift assays. EMSAs showed that Sp1 binding was increased by light stimulation. Western blot analysis showed an increase in Sp1 protein levels in the light-treated cells. Conclusion: We showed that light induced transcription of the VEGF gene through Sp1-binding sites in Y79 cells. Pharmacological intervention which inhibits the signals elicited by light stimulation may be effective to treat the VEGF-mediated retinopathies.

Keywords: 566 retinal neovascularization • 417 gene/expression • 604 transcription