Human SNAP23 adenoviral particles

Disturbed blood flow in vascular endothelial cells (ECs) at arterial branches and bends causes neighboring smooth muscle cells (SMCs) to switch from a quiescent to an activated phenotype, subsequently leading to smooth muscle hyperplasia. Endothelial microRNA-126-3p (miR-126-3p), a key intercellular molecule that increases turnover of recipient SMCs, release of which is reduced by atheroprotective laminar shear (12 dynes/cm2) of ECs. Here, researchers show that atherogenic oscillatory shear, but not atheroprotective pulsatile shear, increases endothelial secretion of non-membrane-bound miR-126-3p and other microRNAs (miRNAs) via activation of the SNAREs, vesicle-associated membrane protein 3 (VAMP3) and synaptosome-associated protein 23 (SNAP23). Knockdown of VAMP3 and SNAP23 reduced endothelial cell secretion of miR-126-3p and miR-200a-3p, as well as EC coculture-induced inhibition of proliferation, migration, and contraction markers in SMCs. Systemic inhibition of VAMP3 and SNAP23 by rapamycin or periventricular application of the endocytosis inhibitor dynasore improved perturbed flow-induced neointima formation, which was exacerbated by luminal overexpression of SNAP23. These findings demonstrate the flow pattern specificity of SNARE activation and its contribution to miRNA-mediated EC-SMC communication.

Partial carotid artery ligation resulted in increased expression of VAMP3 and SNAP23 in the endothelium of the common carotid artery 1 week after surgery compared with the unligated right side (Figure 1A). Repeated injections of rapamycin reduced the expression of VAMP3 and SNAP23 in the arteries (Figure 1A). H&E staining showed that neointimal thickening was reduced by 74.8% and 46.7%, respectively, in mice treated with rapamycin or dynasore, as indicated by the ratio of intima to media (Figure 1B). In situ hybridization for miR-126-3p in serial sections showed a concurrent reduction of miR-126-3p in the neointima of rapamycin- and dynasore-treated arteries (Figure 1C), suggesting that endothelial miR-126-3p plays a causal role in neointima formation. Intraluminal application of adenovirus expressing SNAP23 (Ad-SNAP23) increased the expression of SNAP23 in the endothelia (Figure 1D). Neointimal thickening (Figure 1E) and miR-126-3p accumulation (Figure 1F) were significantly exaggerated in the Ad-SNAP23-treated arteries compared with those in controls. Taken together, these results suggest that inhibition of endothelial VAMP3 and SNAP23 and the consequent transfer of EC to SMC miR-126-3p can suppress turbulent flow-induced smooth muscle hyperplasia.

Figure 1. Systemic application of rapamycin ameliorates the disturbed flow-induced neointimal formation, whereas local delivery of Ad-SNAP23 aggravates it. (Zhu J J, et al., 2017)