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O-GlcNAc modification of transcription factor Sp1 mediates hyperglycemia-induced VEGF-A upregulation in retinal cells
Journal article   Open access   Peer reviewed

O-GlcNAc modification of transcription factor Sp1 mediates hyperglycemia-induced VEGF-A upregulation in retinal cells

Kelly Donovan, Oleg Alekseev, Xin Qi, William Cho and Jane Azizkhan-Clifford
Investigative ophthalmology & visual science, v 55(12), pp 7862-7873
28 Oct 2014
DOI: https://doi.org/10.1167/iovs.14-14048
PMID: 25352121
Featured in Collection :   UN Sustainable Development Goals @ Drexel
url
https://doi.org/10.1167/iovs.14-14048View
Published, Version of Record (VoR)Open Access (License Unspecified),  Open

Abstract

Animals Cell Line Disease Models, Animal Endothelial Cells - metabolism Epithelial Cells - metabolism Humans Hyperglycemia - metabolism N-Acetylglucosaminyltransferases - antagonists & inhibitors N-Acetylglucosaminyltransferases - physiology Rats Retina - metabolism Retinal Pigment Epithelium - metabolism Sp1 Transcription Factor - physiology Transcriptional Activation Up-Regulation - drug effects Vascular Endothelial Growth Factor A - metabolism
Proangiogenic protein VEGF-A contributes significantly to retinal lesions and neovascularization in diabetic retinopathy (DR). In preclinical DR, hyperglycemia can upregulate VEGF-A in retinal cells. The VEGF-A promoter is responsive to the transcription factor specificity protein 1 (Sp1). The O-GlcNAc modification is driven by glucose concentration and has a profound effect on Sp1 activity. This study investigated the effects of hyperglycemia on Sp1-mediated expression of VEGF-A in the retinal endothelium and pigment epithelium. Hyperglycemia-exposed ARPE-19 (human retinal pigment epithelial cells) and TR-iBRB (rat retinal microendothelial cells) were assayed for levels of VEGF-A by qRT-PCR, Western blot, and ELISA. Small molecule inhibitors of O-GlcNAc transferase (OGT) or O-GlcNAcase (OGA) were used to manipulate O-GlcNAc levels. Vascular endothelial growth factor-A protein and transcript were measured in cells depleted of OGT or Sp1 by shRNA. The proximal VEGF-A promoter was analyzed for glucose sensitivity by luciferase assay. Chromatin immunoprecipitation (ChIP) was used to assess Sp1 occupancy on the VEGF-A promoter. Hyperglycemia increased VEGF-A promoter activity and upregulated VEGF-A transcript and protein. Elevation of O-GlcNAc by OGA inhibitors was sufficient to increase VEGF-A. O-GlcNAc transferase inhibition abrogated glucose-driven VEGF-A. Cellular depletion of OGT or Sp1 by shRNA significantly abrogated glucose-induced changes in VEGF-A. ChIP analysis showed that hyperglycemia significantly increased binding of Sp1 to the VEGF-A promoter. Hyperglycemia-driven VEGF-A production is mediated by elevated O-GlcNAc modification of the Sp1 transcription factor. This mechanism may be significant in the pathogenesis of preclinical DR through VEGF-A upregulation.

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Web of Science research areas
Ophthalmology
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