Concerted inhibition of HIF-1α and -2α expression markedly suppresses angiogenesis in cultured RPE cells

Takeshi Nakajima, Emi Nakajima, Thomas R. Shearer, Mitsuyoshi Azuma

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

HIF-1α is known to play an important role in the induction of VEGF by hypoxia in retinal pigment epithelial (RPE) cells. However, the involvement of the other isoform, HIF-2α, in RPE cells remains unclear. Thus, the purpose of present study was to clarify the role of HIF-2α during induction of angiogenic genes in hypoxic RPE cells. When human RPE cells (ARPE-19) were cultured under hypoxic conditions, HIF-1α and HIF-2α proteins increased. This induced an increase in mRNA for VEGF, causing secretion of VEGF protein into the medium. This conditioned medium induced tube formation in human vascular endothelial cells (HUVEC). The increased expression of mRNA for VEGF in hypoxic RPE cells was partially inhibited by HIF-1α siRNA, but not by HIF-2α siRNA. However, co-transfection of HIF-1α siRNA and HIF-2α siRNA augmented downregulation of VEGF mRNA and protein in hypoxic RPE cells and inhibited formation of tube-like structures in HUVEC. GeneChip and PCR array analyses revealed that not only VEGF, but also expression of other angiogenic genes were synergistically downregulated by co-transfection of hypoxic RPE cells with HIF-1α and HIF-2α siRNAs. These findings suggest an important compensatory role for the HIF-2α isoform in the regulation of angiogenic gene expression. Thus, suppression of angiogenic genes for HIF-1α and HIF-2α may be a possible therapeutic strategy against retinal angiogenesis in Age-related macular degeneration (ARMD).

Original languageEnglish (US)
Pages (from-to)113-122
Number of pages10
JournalMolecular and Cellular Biochemistry
Volume383
Issue number1-2
DOIs
StatePublished - Jul 22 2013

Keywords

  • Age-related macular degeneration
  • Hypoxia
  • Hypoxia-inducible factor-1α and -2α
  • Retinal pigment epithelial cells
  • Vascular endothelial growth factor

ASJC Scopus subject areas

  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology

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