ERO1 alpha deficiency impairs angiogenesis by increasing N-glycosylation of a proangiogenic VEGFA

Redox Biol. 2022 Oct:56:102455. doi: 10.1016/j.redox.2022.102455. Epub 2022 Aug 27.

Abstract

N-glycosylation and disulfide bond formation are two essential steps in protein folding that occur in the endoplasmic reticulum (ER) and reciprocally influence each other. Here, to analyze crosstalk between N-glycosylation and oxidation, we investigated how the protein disulfide oxidase ERO1-alpha affects glycosylation of the angiogenic VEGF121, a key regulator of vascular homeostasis. ERO1 deficiency, while retarding disulfide bond formation in VEGF121, increased utilization of its single N-glycosylation sequon, which lies close to an intra-polypeptide disulfide bridge, and concomitantly slowed its secretion. Unbiased mass-spectrometric analysis revealed interactions between VEGF121 and N-glycosylation pathway proteins in ERO1-knockout (KO), but not wild-type cells. Notably, MAGT1, a thioredoxin-containing component of the post-translational oligosaccharyltransferase complex, was a major hit exclusive to ERO1-deficient cells. Thus, both a reduced rate of formation of disulfide bridges, and the increased trapping potential of MAGT1 may increase N-glycosylation of VEGF121. Extending our investigation to tissues, we observed altered lectin staining of ERO1 KO breast tumor xenografts, implicating ERO1 as a physiologic regulator of protein N-glycosylation. Our study, highlighting the effect of ERO1 loss on N-glycosylation of proteins, is particularly relevant not only to angiogenesis but also to other cancer patho-mechanisms in light of recent findings suggesting a close causal link between alterations in protein glycosylation and cancer development.

Keywords: Angiogenesis; ERO1 alpha; N-glycosylation; Oxidative folding; VEGFA.

MeSH terms

  • Disulfides / metabolism
  • Glycosylation
  • Humans
  • Lectins / metabolism
  • Membrane Glycoproteins* / metabolism
  • Neovascularization, Pathologic / genetics
  • Oxidation-Reduction
  • Oxidoreductases / metabolism
  • Protein Folding
  • Thioredoxins / metabolism
  • Vascular Endothelial Growth Factor A* / genetics
  • Vascular Endothelial Growth Factor A* / metabolism

Substances

  • Disulfides
  • Lectins
  • Membrane Glycoproteins
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • Thioredoxins
  • ERO1A protein, human
  • Oxidoreductases