Transglutaminase 2-Mediated Activation of β-Catenin Signaling Has a Critical Role in Warfarin-Induced Vascular Calcification

Objective-Accumulating experimental evidence implicates beta-catenin signaling and enzyme transglutaminase 2 (TG2) in the progression of vascular calcification, and our previous studies have shown that TG2 can activate beta-catenin signaling in vascular smooth muscle cells (VSMCs). Here we investigated the role of the TG2/beta-catenin signaling axis in vascular calcification induced by warfarin. Methods and Results-Warfarin-induced calcification in rat A10 VSMCs is associated with the activation of beta-catenin signaling and is independent of oxidative stress. The canonical beta-catenin inhibitor Dkk1, but not the Wnt antagonist Wif-1, prevents warfarin-induced activation of beta-catenin, calcification, and osteogenic transdifferentiation in VSMCs. TG2 expression and activity are increased in warfarin-treated cells, in contrast to canonical Wnt ligands. Vascular cells with genetically or pharmacologically reduced TG2 activity fail to activate beta-catenin in response to warfarin. Moreover, warfarin-induced calcification is significantly reduced on the background of attenuated TG2 both in vitro and in vivo. Conclusion-TG2 is a critical mediator of warfarin-induced vascular calcification that acts through the activation of beta-catenin signaling in VSMCs. Inhibition of canonical beta-catenin pathway or TG2 activity prevents warfarin-regulated calcification, identifying the TG2/beta-catenin axis as a novel therapeutic target in vascular calcification. (Arterioscler Thromb Vasc Biol. 2012;32:123-130.)