Nox 5 overexpression induces the activation of the unfolded protein response in human aortic endothelial cells

Oxidative stress is a critical mechanism that underlies the pathophysiology of cardiovascular diseases. At the vascular level, an enhanced NADPH oxidase-mediated superoxide production associates with endothelial dysfunction, metalloprotease secretion, cellular senescence, and more recently activation of the unfolded protein response (UPR). Human aortic endothelial cells (HAEC) were infected with Nox 5 or GFP adenovirus, RNA was extracted 12, 18 and 24 hours after infection and used to determine mRNA expression by a Gene Chip Human Transcriptome Array 2.0 (Affymetrix). Nox 5 overexpression after adenoviral infection in HAEC resulted in a significant enhancement of extracellular superoxide and hydrogen peroxide production and led to a significant increase in cellular apoptosis by caspases 3 and 7. The ontological analysis of the array showed an upregulation of UPR. Infection of HAEC with Nox 5 adenovirus activated the UPR pathway, increasing Ire1α and CHOP mRNA expression, GRP78 protein levels and reducing calnexin protein expression. Additionally, Nox 5 overexpression significantly reduced Nox 4 and NOS3 mRNA expression. Nox 5 overexpression promotes a situation of oxidative stress in HAEC, which alters correct protein folding and activates the UPR pathway.