Hypoxia-Mediated Regulation of Histone Demethylases Affects Angiogenesis-Associated Functions in Endothelial Cells

Arterioscler Thromb Vasc Biol. 2020 Nov;40(11):2665-2677. doi: 10.1161/ATVBAHA.120.315214. Epub 2020 Sep 17.

Abstract

Objective: Previous studies have demonstrated that the expression of several lysine (K)-specific demethylases (KDMs) is induced by hypoxia. Here, we sought to investigate the exact mechanisms underlying this regulation and its functional implications for endothelial cell function, such as angiogenesis. Approach and Results: We analyzed the expression changes of KDMs under hypoxia and modulation of HIF (hypoxia-inducible factor) expression using GRO-Seq and RNA-Seq in endothelial cells. We provide evidence that the majority of the KDMs are induced at the level of nascent transcription mediated by the action of HIF-1α and HIF-2α. Importantly, we show that transcriptional changes at the level of initiation represent the major mechanism of gene activation. To delineate the epigenetic effects of hypoxia and HIF activation in normoxia, we analyzed the genome-wide changes of H3K27me3 using chromosome immunoprecipitation-Seq. We discovered a redistribution of H3K27me3 at ≈2000 to 3000 transcriptionally active loci nearby genes implicated in angiogenesis. Among these, we demonstrate that vascular endothelial growth factor A (VEGFA) expression is partly induced by KDM4B- and KDM6B-mediated demethylation of nearby regions. Knockdown of KDM4B and KDM6B decreased cell proliferation, tube formation, and endothelial sprouting while affecting hundreds of genes associated with angiogenesis. These findings provide novel insights into the regulation of KDMs by hypoxia and the epigenetic regulation of VEGFA-mediated angiogenesis.

Conclusions: Our study describes an additional level of epigenetic regulation where hypoxia induces redistribution of H3K27me3 around genes implicated in proliferation and angiogenesis. More specifically, we demonstrate that KDM4B and KDM6B play a key role in modulating the expression of the major angiogenic driver VEGFA.

Keywords: cardiovascular diseases; cell proliferation; endothelial cells; hypoxia; lysine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Cell Hypoxia
  • Cells, Cultured
  • Demethylation
  • Histone Demethylases / genetics
  • Histone Demethylases / metabolism*
  • Histones / metabolism*
  • Human Umbilical Vein Endothelial Cells / enzymology*
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Jumonji Domain-Containing Histone Demethylases / genetics
  • Jumonji Domain-Containing Histone Demethylases / metabolism
  • Neovascularization, Physiologic*
  • Protein Processing, Post-Translational
  • Signal Transduction
  • Vascular Endothelial Growth Factor A / genetics
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Basic Helix-Loop-Helix Transcription Factors
  • HIF1A protein, human
  • Histones
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • endothelial PAS domain-containing protein 1
  • Histone Demethylases
  • Jumonji Domain-Containing Histone Demethylases
  • KDM4B protein, human
  • KDM6B protein, human