17β-estradiol enhances signalling mediated by VEGF-A-delta-like ligand 4-notch1 axis in human endothelial cells

PLoS One. 2013 Aug 13;8(8):e71440. doi: 10.1371/journal.pone.0071440. eCollection 2013.

Abstract

Estrogens play a protective role in coronary artery disease. The mechanisms of action are still poorly understood, although a role for estrogens in stimulation of angiogenesis has been suggested. In several cell types, estrogens modulate the Notch pathway, which is involved in controlling angiogenesis downstream of vascular endothelial growth factor A (VEGF-A). The goal of our study was to establish whether estrogens modulate Notch activity in endothelial cells and the possible consequences on angiogenesis. Human umbilical vein endothelial cells (HUVECs) were treated with 17β-estradiol (E2) and the effects on Notch signalling were evaluated. E2 increased Notch1 processing as indicated by i) decreased levels of Notch1 transmembrane subunit ii) increased amount of Notch1 in nuclei iii) unaffected level of mRNA. Similarly, E2 increased the levels of the active form of Notch4 without altering Notch4 mRNA. Conversely, protein and mRNA levels of Notch2 were both reduced suggesting transcriptional repression of Notch2 by E2. Under conditions where Notch was activated by upregulation of Delta-like ligand 4 (Dll4) following VEGF-A treatment, E2 caused a further increase of the active form of Notch1, of the number of cells with nuclear Notch1 and of Hey2 mRNA. Estrogen receptor antagonist ICI 182.780 antagonized these effects suggesting that E2 modulation of Notch1 is mediated by estrogen receptors. E2 treatment abolished the increase in endothelial cells sprouting caused by Notch inhibition in a tube formation assay on 3D Matrigel and in mouse aortic ring explants. In conclusion, E2 affects several Notch pathway components in HUVECs, leading to an activation of the VEGF-A-Dll4-Notch1 axis and to a modulation of vascular branching when Notch signalling is inhibited. These results contribute to our understanding of the molecular mechanisms of cardiovascular protection exerted by estrogens by uncovering a novel role of E2 in the Notch signalling-mediated modulation of angiogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Endothelial Cells / drug effects*
  • Endothelial Cells / metabolism*
  • Estradiol / pharmacology*
  • Estrogen Receptor alpha / metabolism
  • Estrogen Receptor beta / metabolism
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Ligands
  • Membrane Proteins / metabolism*
  • Mice
  • Neovascularization, Physiologic / drug effects
  • Receptor, Notch1 / metabolism*
  • Signal Transduction / drug effects*
  • Vascular Endothelial Growth Factor A / metabolism*

Substances

  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • Intracellular Signaling Peptides and Proteins
  • Ligands
  • Membrane Proteins
  • Receptor, Notch1
  • Vascular Endothelial Growth Factor A
  • delta protein
  • Estradiol

Grant support

This work was supported by a grant from Fondazione Annamaria Sechi per il Cuore (FASC), Italy. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.