Abstract 348: Loss of Cadherin-11 Prevents Aortic Valve Interstitial Cell Contraction

Abstract

Introduction: Calcific aortic valve disease affects 25% of the Western population over 65. Dystrophic calcification is initiated by TGF-β-mediated myofibroblastic differentiation of resident aortic valve interstitial cells (AVICs), which exhibit increased cell contractility and a subsequent imbalance of intercellular tension, which is speculated to lead to apoptosis of AVICs. Cadherin-11 (CDH11), a mechanosensitive transmembrane protein involved in cell-cell adhesion, is responsible for mediating much of this intercellular tension. While cadherins are known to complex with catenins intracellularly, downstream signaling is poorly understood. Both CDH11 and α-smooth muscle actin (αSMA), a myofibroblast marker involved in cell contractility, are overexpressed in diseased human valves, though previous in vitro work suggests they have an inverse relationship. Materials and Methods: AVICs were isolated from immortalized WT, CDH11 +/- and CDH11 -/- mice. They were exposed to 24 hours of 10% equibiaxial strain on the Flexcell-4000 system to recapitulate the mechanical environment of the valves and analyzed for αSMA, β-catenin, and p120-catenin via western blot. AVICs were also seeded on collagen gels and treated with 1 ng/ml murine TGF-β1 to assay contractility or plated on coverslips and stained for myosin light chain II (MLC II). Results and Discussion: Loss of CDH11 in AVICs results in a dramatic increase in αSMA ( A ). Though this suggests the cells would be highly contractile, we observe reduced contractility in CDH11 +/- and CDH11 -/- AVICs ( B ). Increases in β-catenin and p120-catenin expression indicate dramatic changes in intracellular cadherin signaling ( A ), and immunofluorescence shows a decrease in MLC II ( C ). Thus, loss of CDH11 may prevent contraction ( B ) by either preventing linkage between contractile AVICs or preventing MLC II expression. These results indicate that CDH11 may be a promising therapeutic target for calcific aortic valve disease.