Essential role of smooth muscle STIM1 in hypertension and cardiovascular dysfunction

Objectives-Chronic hypertension is the most critical risk factor for cardiovascular disease, heart failure, and stroke. Approach and Results-Here we show that wild-Type mice infused with angiotensin II develop hypertension, cardiac hypertrophy, perivascular fibrosis, and endothelial dysfunction with enhanced stromal interaction molecule 1 (STIM1) expression in heart and vessels. All these pathologies were significantly blunted in mice lacking STIM1 specifically in smooth muscle (Stim1^SMC-/-). Mechanistically, STIM1 upregulation during angiotensin II-induced hypertension was associated with enhanced endoplasmic reticulum stress, and smooth muscle STIM1 was required for endoplasmic reticulum stress-induced vascular dysfunction through transforming growth factor-β and nicotinamide adenine dinucleotide phosphate oxidase-dependent pathways. Accordingly, knockout mice for the endoplasmic reticulum stress proapoptotic transcriptional factor, CCAAT-enhancer-binding protein homologous protein (CHOP^-/-), were resistant to hypertension-induced cardiovascular pathologies. Wild-Type mice infused with angiotensin II, but not Stim1^SMC-/- or CHOP^-/- mice showed elevated vascular nicotinamide adenine dinucleotide phosphate oxidase activity and reduced phosphorylated endothelial nitric oxide synthase, cGMP, and nitrite levels. Conclusions-Thus, smooth muscle STIM1 plays a crucial role in the development of hypertension and associated cardiovascular pathologies and represents a promising target for cardiovascular therapy.