Purpose: Proangiogenic protein vascular endothelial growth factor A (VEGF-A) contributes significantly to retinal lesions and neovascularization in diabetic retinopathy (DR). In pre-clinical 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. Methods: 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. VEGF-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. Results: 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. OGT 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. Conclusions: 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 pre-clinical diabetic retinopathy through VEGF-A upregulation.
Pharmacology, Toxicology and Pharmaceutical Science
2
3%
Medicine and Dentistry
2
3%
Other
3
5%
Unknown
19
31%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 8. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 04 July 2017.
All research outputs
#6,437,409
of 33,834,589 outputs
Outputs from Investigative Ophthalmology & Visual Science
#1,781
of 12,851 outputs
Outputs of similar age
#59,592
of 304,418 outputs
Outputs of similar age from Investigative Ophthalmology & Visual Science
#29
of 142 outputs
Altmetric has tracked 33,834,589 research outputs across all sources so far. Compared to these this one has done well and is in the 80th percentile: it's in the top 25% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 12,851 research outputs from this source. They typically receive a little more attention than average, with a mean Attention Score of 5.1. This one has done well, scoring higher than 85% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 304,418 tracked outputs that were published within six weeks on either side of this one in any source. This one has done well, scoring higher than 80% of its contemporaries.
We're also able to compare this research output to 142 others from the same source and published within six weeks on either side of this one. This one has done well, scoring higher than 78% of its contemporaries.
