Pulmonary arterial hypertension (PAH) is a disease characterized by the vascular remodeling of the pulmonary arterioles, including formation of plexiform and concentric lesions comprised of proliferative endothelial cells. We recently found that disruption of the G protein-coupled receptor signaling axis comprised of the ligand apelin and the receptor APJ leads to significant worsening of hypoxia induced pulmonary hypertension (PH) in mice, and found that the pathway is also perturbed in clinical PAH. To further characterize the downstream endothelial targets which may be utilized by apelin-APJ signaling to protect against the remodeling processes in PAH, we carried out a microRNA (miRNA) array analysis of pulmonary artery endothelial cells (PAECs) subjected to knockdown of apelin, APJ, or both. We identified two miRNAs (miR-424 and miR-503) that are highly expressed in PAECs, but are significantly downregulated in the context of apelin/APJ knockdown. Remarkably, these miRNAs are also markedly decreased in the experimental monocrotaline rat model of PH, as well as in PAECs isolated from patients with clinically diagnosed PAH. Our in vitro functional studies demonstrated that both miR-424 and miR-503 exert anti-proliferative, anti-angiogenic effects, via a mechanism that at least in part involves targeting of the FGF signaling pathway. We found that restoration of miR-424/503 expression in the monocrotaline induced model of PH by intranasal lentiviral delivery can significantly ameliorate the severity of the disease. Based o these preliminary data, we hypothesize that miR-424/503 play a critical role in maintaining pulmonary vascular homeostasis, and that disruption of their expression serves a critical contribution to the aberrant endothelial proliferation which is a hallmark of PAH. We propose the following aims to further evaluate the role of miR-424/503 in PAH: 1) Determine the transcriptional regulatory mechanisms of miR-424/503 in PAECs that involves targeting of the myocyte-specific enhancer factor 2 (MEF2) by apelin-APJ signaling, 2) Evaluate the efficacy of endothelial specific expression of miR-424/503 in experimental models of PH, and 3) Further validate the role for miR-424/503 in clinical PAH.

Public Health Relevance

Pulmonary arterial hypertension (PAH) is a syndrome in which remodeling of the pulmonary arteries and increased pulmonary vascular resistance result in right ventricular failure, and if untreated ultimately leads to death. The limited existing therapies have improved outcome but mortality remains exceedingly high (up to 45% mortality at 3 years after diagnosis). We seek to define a novel microRNA based molecular mechanism that may be a key determinant of the disease process that will lead to better understanding of the mechanism of PAH and may ultimately identify novel pathways that can serve as therapeutic targets.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL113005-02
Application #
8534272
Study Section
Respiratory Integrative Biology and Translational Research Study Section (RIBT)
Program Officer
Caler, Elisabet V
Project Start
2012-09-01
Project End
2017-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
2
Fiscal Year
2013
Total Cost
$396,270
Indirect Cost
$158,270
Name
Yale University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Kim, Jongmin; Hwangbo, Cheol; Hu, Xiaoyue et al. (2015) Restoration of impaired endothelial myocyte enhancer factor 2 function rescues pulmonary arterial hypertension. Circulation 131:190-9
Mehrotra, Devi; Wu, Jingxia; Papangeli, Irinna et al. (2014) Endothelium as a gatekeeper of fatty acid transport. Trends Endocrinol Metab 25:99-106
Kim, Jun-Dae; Kang, Yujung; Kim, Jongmin et al. (2014) Essential role of Apelin signaling during lymphatic development in zebrafish. Arterioscler Thromb Vasc Biol 34:338-45
Kang, Yujung; Kim, Jongmin; Anderson, Joshua P et al. (2013) Apelin-APJ signaling is a critical regulator of endothelial MEF2 activation in cardiovascular development. Circ Res 113:22-31
Kim, Jongmin; Kang, Yujung; Kojima, Yoko et al. (2013) An endothelial apelin-FGF link mediated by miR-424 and miR-503 is disrupted in pulmonary arterial hypertension. Nat Med 19:74-82