Functional changes in pulmonary arterial endothelial cells associated with BMPR2 mutations.

Hu Wang,Daniel J Penny,Li Sun,Lei Huo,Wenxin Zou,Ruirui Ji,Yuxin Fan,Lei Li,Guoliang Wang,Jie Meng,Qiqiong Cui,Zhaohui Li,Weili Zhang

doi:10.1371/journal.pone.0106703

Abstract

Pulmonary arterial hypertension (PAH) is a devastating disease characterized by abnormal remodeling of small, peripheral pulmonary arteries. Germline mutations in the bone morphogenetic protein receptor type 2 (BMPR2) gene are a major risk factor for developing PAH. At present, the correlation between the BMPR2 mutation and the patient's prognosis remains controversial despite several investigations. In this study, we explored the functional effects of four BMPR2 mutations to dissect the functional significance of the BMPR2 gene defect. Cellular immunofluorescence assay of four mutants (Tyr67Cys, Thr268fs, Ser863Asn, and Gln433X) revealed that the BMPR2 protein containing Thr268fs, Ser863Asn, or Gln433X exhibited abnormal subcellular localization. The BrdU incorporation and TUNEL assay suggested that any of the BMPR2 mutations Thr268fs, Ser863Asn, or Gln433X could improve endothelial cell apoptosis and decrease cell proliferation. All of the four mutants could inhibit nitric oxide (NO) synthesis in HLMVE cells, and ET-1 levels increased in the cells transfected with mutant Ser863Asn. Our results will improve the understanding of the genotype-phenotype correlations and mechanisms associated with BMPR2 mutations.

Highlights

Pulmonary arterial hypertension (PAH) is a rare but devastating disease characterized by pulmonary vascular proliferation and remodeling, resulting in loss of patency of the pulmonary arteries [1]
Effects of bone morphogenetic protein receptor type 2 gene (BMPR2) mutations on human lung microvascular endothelial (HLMVE) cell proliferation The HLMVE cells were transfected with BMPR2 wild-type or mutant constructs, and the cell proliferation was analyzed by incorporating Brdu
The results showed that the HLMVE cells transfected with mutants Thr268fs, Gln433X, or Ser863Asn demonstrated significantly decreased cell proliferation compared with cells transfected with wild-type BMPR2 (Figure 2)

Summary

Introduction

Pulmonary arterial hypertension (PAH) is a rare but devastating disease characterized by pulmonary vascular proliferation and remodeling, resulting in loss of patency of the pulmonary arteries [1]. A key event in the pathophysiology of PAH is dysregulation of endothelial-dependent regulators, including nitric oxide (NO) and endothelin (ET), which, when combined with abnormal proliferation of endothelial and smooth muscle cells and vascular remodeling, results in increased pulmonary arterial pressure and vascular resistance [1,2]. Germline mutations in the bone morphogenetic protein receptor type 2 gene (BMPR2), a member of the transforming growth factor (TGF)-b superfamily of transmembrane serine/threonine kinase receptors, were identified in at least 50% of familial cases and as many as 40% of sporadic cases [5,6,7,8]. Bone morphogenic proteins (BMPs) may modulate a number of pathophysiological processes, in the vascular smooth muscle (VSM) and in the endothelium, which may contribute to the development of PAH. BMP has been shown to modulate the formation of the key transmitters, NO [9] and ET [10], and to regulate endothelial cell migration [11], as well as survival and proliferation [12]

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Results

Conclusion