Does ER stress increase cell-surface GRP78 in endothelial cells?

In the aging vasculature, chronic cardiovascular risk factors induce endoplasmic reticulum (ER) stress, driving pathological changes in endothelial cells via localized autoimmune mechanisms.

ER stress and cell-surface translocation

• Typically an ER-resident chaperone retained by its C-terminal KDEL motif, GRP78 translocates to the endothelial plasma membrane when ER stress upregulates its expression and saturates KDEL receptor retrieval machinery.
• This active translocation is documented across multiple vascular beds, including human aortic, retinal, and brain microvascular endothelial cells, exposing GRP78 to the extracellular environment.

Immune recognition and downstream activation

• Once on the cell surface (csGRP78), GRP78 acts as an immunogenic neoantigen, triggering a loss of self-tolerance and the generation of circulating anti-GRP78 autoantibodies.
• Direct binding of anti-GRP78 autoantibodies to csGRP78 activates canonical NF-κB signaling, characterized by IκBα degradation and p65 nuclear translocation.
• This transcriptional activation upregulates vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), facilitating monocyte adhesion, leukocyte transmigration, and atherosclerotic plaque progression.
• Beyond localized adhesion, this antibody-receptor engagement mobilizes intracellular calcium to upregulate tissue factor procoagulant activity and alters junctional proteins (such as VE-cadherin), leading to increased vascular permeability and blood-brain barrier disruption.

Bottom line

• Bottom line: ER stress-induced translocation of GRP78 to the endothelial cell surface exposes a pathogenic neoantigen. Binding by anti-GRP78 autoantibodies triggers canonical NF-κB signaling, directly linking cellular stress to vascular inflammation, hypercoagulability, and barrier breakdown.