Abstract 11488: MicroRNA-141 is a Novel Regulator of BMP-2-Mediated Calcification in Aortic Stenosis
Bone morphogenic protein 2 (BMP-2) is a major regulator of aortic valve calcification and understanding its molecular regulation may uncover novel treatment approaches to limit calcific aortic stenosis. miRNAs are essential post-transcriptional modulators of gene expression which coordinate and integrate multiple regulatory pathways involved in normal and abnormal development. We investigated the role of miRNA-141 in the regulation of BMP-2-dependent aortic valve calcification and determined whether such signaling may account for aggressive stenosis observed in bicuspid aortic valves. Porcine valvular interstitial cells (VICs) were isolated, then transfected with miRNA-141 or control miRNA and stimulated with TGF-β to induce calcification. BMP-2 and Runx2 levels were determined by immunoblotting and RT-PCR. Aortic valve leaflets obtained intraoperatively from patients with stenotic bicuspid (BAV) and tricuspid (TAV; N=10/group) aortic valves were submitted for miRNA array analysis, BMP-2 immunoblotting and histological and immunohistochemical analyses. Stimulation of porcine VICs with TGF-β induced BMP-2 signaling and calcification as detected by increased alkaline phosphatase expression. Transfection with miRNA-141 completely restored alkaline phosphatase levels. Profile analyses of miRNA expression using a microarray containing 1583 human miRNA probes demonstrated differential expression of 35 of 1583 miRNA sequences in BAV vs. TAV samples. Eight miRNAs including miRNA-152, -373, -30e, -145 were upregulated and 27, which included miRNA-125b, -1260, -27a, -141, were down-regulated. Notably, expression of miRNA-141, a known repressor of BMP-2-mediated osteogenesis, was decreased 14.5-fold in BAV vs. TAV leaflets. This was associated with an increase in BMP-2 protein expression in BAV leaflets. We report a completely novel and previously unrecognized role of miRNA-141 as a regulator of BMP-2-dependent aortic valvular calcification and demonstrate marked attenuation of miRNA-141 expression in patients with BAV-associated severe aortic stenosis. Therapeutic targeting of miRNA-141 may serve as a novel treatment strategy to limit progressive calcification in aortic stenosis.
- © 2011 by American Heart Association, Inc.