Endoplasmic reticulum stress and the development of endothelial dysfunction.

The vascular endothelium plays a critical role in cardiovascular homeostasis, and thus identifying the underlying causes of endothelial dysfunction has important clinical implications. In this regard, the endoplasmic reticulum (ER) has recently emerged as an important regulator of metabolic processes. Dysfunction within the ER, broadly termed ER stress, evokes the unfolded protein response (UPR), an adaptive pathway that aims to restore ER homeostasis. Although the UPR is the first line of defense against ER stress, chronic activation of the UPR leads to cell dysfunction and death and has recently been implicated in the pathogenesis of endothelial dysfunction. Numerous risk factors for endothelial dysfunction can induce ER stress, which may in turn disrupt endothelial function via direct effects on endothelium-derived vasoactive substances or by activating other pathogenic cellular networks such as inflammation and oxidative stress. This review summarizes the available data linking ER stress to endothelial dysfunction.