Mechanosensitive microRNA-181b Regulates Aortic Valve Endothelial Matrix Degradation by Targeting TIMP3

Abstract

Calcific aortic valve disease (CAVD) is a major cause of morbidity in the aging population, but the underlying mechanisms of its progression remain poorly understood. Aortic valve calcification preferentially occurs on the fibrosa, which is subjected to disturbed flow. The side-specific progression of the disease is characterized by inflammation, calcific lesions, and extracellular matrix (ECM) degradation. Here, we explored the role of mechanosensitive microRNA-181b and its downstream targets in human aortic valve endothelial cells (HAVECs). Mechanistically, miR-181b is upregulated in OS and fibrosa, and it targets TIMP3, SIRT1, and GATA6, correlated with increased gelatinase/MMP activity. Overexpression of miR-181b led to decreased TIMP3 and exacerbated MMP activity as shown by gelatinase assay, and miR-181b inhibition decreased gelatinase activity through the repression of TIMP3 levels. Luciferase assay showed specific binding of miR-181b to the TIMP3 gene. Overexpression of miR-181b in HAVECs subjected to either LS or OS increased MMP activity, and miR-181b inhibition abrogated shear-sensitive MMP activity. These studies suggest that targeting this shear-dependent miRNA may provide a novel noninvasive treatment for CAVD.

Biology of Tissue Inhibitor of Metalloproteinase 3 (TIMP3), and Its Therapeutic Implications in Cardiovascular Pathology

“…Through binding to, and inhibiting Timp3 expression, miR-21 enhances survival, migration and capillary formation ability of human umbilical vein endothelial cell lines (HUVECs) (Hu et al, 2016). miR-181b targets Timp3 and reduces apoptosis of cardiomyocytes (Gao et al, 2017), but enhances gelatinases/MMP activity in human aortic valve endothelial cells which may contribute to calcific aortic valve disease (Heath et al, 2018). MiR-181b is increased in human atherosclerotic plaques and abdominal aortic aneurysms (AAA), and inhibition of miR-181b suppressed the development and progression of atherosclerosis and aneurysms through increasing expression of TIMP3, elastin, and collagen (Di Gregoli et al, 2017).…”

Enlightening the Association between Bicuspid Aortic Valve and Aortopathy

“…Interestingly, miR-29b has already been shown to promote aortic valve interstitial cell calcification by inhibiting TGF-β3 through the activation of wnt3/β-catenin and to induce elastin downregulation, contributing to inorganic phosphorus-induced osteoblastic differentiation in vascular SMCs [ 114 ]. Moreover, a reduction of miR-195 in BAV was suggested to promote calcification of valve interstitial cells via SMAD7 targeting, and the mechanosensitive miR-181b regulates AV endothelial matrix degradation by targeting TIMP3 [ 115 , 116 ]. Other miRs reported to be deregulated in AV calcification and potentially mediating the calcification process are miR-204 and miR-449c [ 117 , 118 ].…”

“…Vascular physiology is maintained through alterations in shear stress that potentially lead to miR-regulated differential gene expression in endothelial cells. MiRNAs induced by laminar shear stress, like miR-126, 27b, and 143/145 were identified as leading to protection from atherosclerosis, whilst miRNAs induced by low oscillatory shear stress (like miR-181b) were identified as leading to pathological vascular phenotypes [ 116 , 137 , 138 , 139 ], potentially triggering cardiovascular diseases.…”

Endothelial Cell Aging: How miRNAs Contribute?

“…However, knockdown of miR-181a/b in EC significantly increased the production of nitric oxide (NO), even though the response of acetylcholine in the aortic ring of miR-181a/b knockout mice were not altered compared to wild-type mice [ 140 ]. In turn, miR-181b was one of the mechanosensitive miRNAs and upregulated in human aortic valve endothelial cells (HAVECs) sheared for 24 h under low-magnitude bidirectional shear stress (oscillatory shear stress; OS) [ 141 ]. Overexpression of miR-181b inhibited the tissue inhibitor of metalloproteinase 3 (TIMP3) in HAVECs under OS conditions suggesting that miR-181b induces ECM degradation by increased MMP activity.…”