Abstract 13395: A Systems-Biology Approach Reveals That MicroRNA-21 Integrates Diverse Pathogenic Signaling to Control Pulmonary Hypertension
Background: Pulmonary hypertension (PH) is a vascular disorder driven by diverse etiologies such as hypoxia, bone morphogenetic protein (BMP signaling), and inflammation, among others. MicroRNA (miRNA) can maintain coordinate control of these molecular pathways, but their importance in PH is poorly defined.
Objective: We aim to identify miRNA that integrate diverse pathogenic stimuli to control the development of PH.
Results: Guided by a unique network-based in silico approach, we identify a set of miRNA, including miR-21, predicted to associate with multiple pathogenic pathways central to PH. As validation, in cultured human pulmonary artery endothelial cells (HPAEC), we have found that miR-21 is up-regulated by hypoxia (1.8-fold ± 0.11 SEM) and the BMP Receptor Type II (BMPRII) [0.55-fold ± 0.17 expression after RNAi-knockdown of BMPRII]. In a reciprocal feedback loop, miR-21 down-regulates BMPRII (0.74-fold ± 0.08), and inhibition of miR-21 increases BMPRII (1.49-fold ± 0.02). Downstream of such regulation, miR-21 represses Rho/Rho kinase signaling, as miR-21 inhibition up-regulates its direct target RhoB (1.61-fold ± 0.12) and Rho kinase-dependent activity (1.75-fold ± 0.07). Consequently, miR-21 induces an anti-angiogenic and pro-vasodilatory state, as miR-21 inhibition increases F-actin stress fibers and decreases nitric oxide synthase levels (0.66-fold ± 0.11). In vivo, miR-21 is up-regulated in pulmonary tissue from rodent models of PH [5.2-fold ± 0.57 in monocrotaline-treated rats; 4.2-fold ± 1.00 in transgenic interleukin-6-expressing mice; 3.5-fold ± 0.40 in constitutive hypoxia inducible factor-expressing (HIF) mice]. Upon induction of disease in miR-21-null mice, RhoB and Rho-kinase activity are increased in the pulmonary vasculature, as shown by immunohistochemistry. An exaggerated manifestation of PH results, with increased right ventricular systolic pressure [38.54 mmHg ± 1.00 (miR-21-null, N=8) vs 27.27 mmHg ± 0.99 (wildtype littermate control, N=8), p=0.007] and worsened histological remodeling.
Conclusions: A novel bioinformatics approach and confirmatory in vivo data delineate a central protective role for miR-21 in PH and, thus, present a validated method to identifying additional PH-modifying miRNA.
- © 2011 by American Heart Association, Inc.