May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
Methylglyoxal-Induced Degradation of HIF-1a: Implications to Diabetic Retinopathy
Author Affiliations & Notes
  • P. C. Pereira
    Center of Ophthalmology, IBILI-Faculty of Medicine of University of Coimbra, Coimbra, Portugal
  • C. Bento
    Center of Ophthalmology, IBILI-Faculty of Medicine of University of Coimbra, Coimbra, Portugal
  • R. Fernandes
    Center of Ophthalmology, IBILI-Faculty of Medicine of University of Coimbra, Coimbra, Portugal
  • A. Fernandes
    Center of Ophthalmology, IBILI-Faculty of Medicine of University of Coimbra, Coimbra, Portugal
  • A. Taylor
    HNRC, Tufts University, Boston, Massachusetts
  • F. Shang
    HNRC, Tufts University, Boston, Massachusetts
  • Footnotes
    Commercial Relationships P.C. Pereira, None; C. Bento, None; R. Fernandes, None; A. Fernandes, None; A. Taylor, None; F. Shang, None.
  • Footnotes
    Support FCT- POCI/SAU-OBS/57772/2004; grants EY 11717 (to FS) and EY 13250 (to AT)
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 1378. doi:https://doi.org/
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    • Get Citation

      P. C. Pereira, C. Bento, R. Fernandes, A. Fernandes, A. Taylor, F. Shang; Methylglyoxal-Induced Degradation of HIF-1a: Implications to Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1378. doi: https://doi.org/.

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

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Abstract

Purpose:: Intracellular production and accumulation of glycating agents such as methylglyoxal (MGO) is a main feature of many pathological complications associated with diabetes including diabetic retinopathy.This study is designed to assess the role of methylglyoxal in degradation of HIF-1a and implications on production of VEGF by human retinal-pigmented epithelial cells (RPE)

Methods:: ARPE-19 cells were submitted to hypoxic conditions (CoCl2 or 2%O2) in the presence or absence of MGO. The role of the proteasome on MGO-induced degradation of HIF-1a was assessed by incubating the cells with proteasome inhibitors (MG132, PS-341). To assess whether degradation of HIF-1a requires prior ubiquitinylation of the protein, HIF-1a was immunoprecipitated and Western blots were probed for ubiquitin conjugates. To assess the requirement for prolyl hydroxylation and ligase Von Hippel-Lindau (VHL) protein, RPE cells were transfected either with the wild type (wt-HIF-1a) or the prolyl hydroxylation mutant (P402/564A) and treated as described above. Levels of VEGF released into the medium were determined by ELISA.

Results:: In RPE, MGO strongly destabilizes HIF-1a by promoting increased degradation of HIF-1a by an ubiquitin-proteasome dependent mechanism. Significantly, the MGO mediated degradation of HIF-1a is independent on the ubiquitin ligase Von Hippel-Lindau (VHL) protein and does not require prior hydroxylation of P402 and P564 as revealed by the sensitivity of the P402/564A-HIF-1a to MGO-dependent degradation. Increased degradation of HIF-1a resulted in decreased production of VEGF by RPE.

Conclusions:: Increased degradation of HIF-1a in the presence of MGO is likely to compromise retina ability to cope with hypoxia at early stages of diabetic retinopathy thus leading to increased endothelial cell death and pericytes dropout.

Keywords: retinal degenerations: cell biology • diabetic retinopathy • protein modifications-post translational 
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