Multi-omics analysis reveals ER stress as a main feature in two endothelial cell models of N-linked congenital disorders of glycosylation.

Glycosylation is one of the most important posttranslational modifications. When the glycosylation machinery is affected, this leads to a congenital disorder of glycosylation (CDG). CDG are a class of rare multisystemic diseases that often affect the endoplasmic reticulum (ER). Although vascular complications have been reported in CDG, the contribution of endothelial dysfunction to these phenotypes remains incompletely understood. Here, we evaluated the effect of glycosylation deficiency on endothelial dysfunction by generating two endothelial cell models using pharmacological inhibitors: tunicamycin (a well-known glycosylation inhibitor at the level of DPAGT1), and 2-deoxy-2-fluoro-D-mannose (FMan). This is a novel inhibitor that inhibits mannose and related sugar-phosphate metabolism. These cell models were subjected to transcriptomics, proteomics, and tracer metabolomics to pinpoint the pathways that are most affected across these different levels. Both transcriptomics and proteomics revealed ER stress as the top upregulated feature. This was functionally characterized by decreased cell growth, induced apoptosis, decreased cell migration, and induced an immune response. The barrier function of the cells was not affected. Here, we demonstrate that N-glycosylation deficiency triggers an ER stress response, contributing to endothelial dysfunction, and investigated ER stress mitigation as a potential therapeutic strategy for CDG.