June 2013
Volume 54, Issue 15
ARVO Annual Meeting Abstract  |   June 2013
High glucose activates ChREBP-mediated HIF-1α and VEGF expression in human RPE cells under normoxia
Author Affiliations & Notes
  • Min-Lee Chang
    HNRCA Tufts University, Boston, MA
  • Chung-Jung Chiu
    HNRCA Tufts University, Boston, MA
  • Fu Shang
    HNRCA Tufts University, Boston, MA
  • Allen Taylor
    HNRCA Tufts University, Boston, MA
  • Footnotes
    Commercial Relationships Min-Lee Chang, None; Chung-Jung Chiu, None; Fu Shang, None; Allen Taylor, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 4577. doi:
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      Min-Lee Chang, Chung-Jung Chiu, Fu Shang, Allen Taylor; High glucose activates ChREBP-mediated HIF-1α and VEGF expression in human RPE cells under normoxia. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4577.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: Because retina-damaging angiogenesis is controlled by VEGF and people with higher glucose intakes are more susceptible to retinal complications that may be due to increased VEGF, it is crucial to elucidate relations between glucose exposure and VEGF expression. We aimed to determine if a carbohydrate response element binding protein (ChREBP) plays a role in the transcriptional up-regulation of hypoxia-inducible factor-1α (HIF-1α) and downstream vascular endothelial growth factor (VEGF) expression in retinal pigment epithelial (RPE) cells exposed to normoxia and high glucose.

Methods: ARPE19 cells were exposed to 5.6, 11, 17, 25 and 30 mM glucose for 48h in serum-free culture media under normoxic (21% O2) conditions. Protein and mRNA expression of indicated genes were determined by immunoblot analyses and real-time RT-PCR, respectively. An enzyme-linked immunosorbent assay (ELISA) was used to detect the concentrations of VEGF in the media. Immunofluorescence (IF) and chromatin immunoprecipitation (ChIP) for ChREBP were used to demonstrate nuclear translocation and HIF-1α gene promoter association, respectively.

Results: Immunoblot analyses showed that HIF-1α levels were positively related to levels of glucose exposure between 5.6-25 mM in the RPE cells, indicating the induction and stabilization of HIF-1α by elevated glucose under normoxic conditions. Human lens epithelial cells and HeLa cells did not respond to high glucose, implying that this phenomenon is cell type-specific. Real-time RT-PCR for HIF-1α and VEGF and ELISA for VEGF indicated that high glucose is associated with elevated production of HIF-1α-induced VEGF, an established inducer of neovascularization, in the RPE cells. IF analyses showed that, although ChREBP was equally expressed under both low (5.6 mM) and high (25 mM) glucose conditions, it appeared more in the nuclear region than in the cytosol of the RPE cells after the high glucose treatment. ChIP analyses suggested a HIF-1α gene promoter association with ChREBP under the high glucose condition. These results imply that RPE cells use cytosolic ChREBP as a glucose sensor to up-regulate HIF-1α expression.

Conclusions: These results suggest a high glucose-induced, ChREBP-mediated, and normoxic HIF activation that may be partially responsible for the neovascularization in both diabetic and age-related retinopathy.

Keywords: 412 age-related macular degeneration • 609 neovascularization • 499 diabetic retinopathy  

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