Tubulin-folding cofactor E deficiency promotes vascular dysfunction by increased endoplasmic reticulum stress

Assessment of endothelial function in humans by measuring flow-mediated dilation (FMD) risk-stratifies individuals with established cardiovascular disease, whereas its predictive value is limited in primary prevention. We therefore aimed to establish and evaluate novel markers of FMD at the population level.

In order to identify novel targets that were negatively correlated with FMD and investigate their contribution to vascular function, we performed a genome-wide association study (GWAS) of 4175 participants of the population based Gutenberg Health Study. Subsequently, conditional knockout mouse models deleting the gene of interest were generated and characterized. GWAS analysis revealed that single-nucleotide polymorphisms (SNPs) in the tubulin-folding cofactor E (TBCE) gene were negatively correlated with endothelial function and TBCE expression. Vascular smooth muscle cell (VSMC)-targeted TBCE deficiency was associated with endothelial dysfunction, aortic wall hypertrophy, and endoplasmic reticulum (ER) stress-mediated VSMC hyperproliferation in mice, paralleled by calnexin up-regulation and exacerbated by the blood pressure hormone angiotensin II. Treating SMMHC-ERT2-Cre^+/−TBCE^fl/fl mice with the ER stress modulator tauroursodeoxycholic acid amplified Raptor/Beclin-1-dependent autophagy and reversed vascular dysfunction.

TBCE and tubulin homeostasis seem to be novel predictors of vascular function and offer a new drug target to ameliorate ER stress-dependent vascular dysfunction.