Bone morphogenetic protein‐7 inhibits endothelial‐mesenchymal transition in pulmonary artery endothelial cell under hypoxia

Pulmonary artery hypertension (PAH) is characterized by structural changes in pulmonary arteries. Increased numbers of cells expressing α‐smooth muscle actin (α‐SMA) is a nearly universal finding in the remodeled artery. It has been confirmed endothelial‐to‐mesenchymal transition (EndoMT) may be a source of those α‐SMA–expressing cells. In addition, the EndoMT is reversible. Here, we show that under hypoxia, the expression of bone morphogenetic protein 7 (BMP‐7) was decreased both in vivo and in vitro. We also found that under normoxia, BMP‐7 deficiency induced spontaneous EndoMT and cell migration. The hypoxia‐induced EndoMT and cell migration were markedly attenuated after pretreatment with rh‐BMP‐7. Moreover, m‐TOR phosphorylation was involved in EndoMT and BMP‐7 suppressed hypoxia‐induced m‐TORC1 phosphorylation in pulmonary artery endothelial cells. Our results demonstrate that BMP‐7 attenuates the hypoxia‐induced EndoMT and cell migration by suppressing the m‐TORC1 signaling pathway. Our study revealed a novel mechanism underlying the hypoxia‐induced EndoMT in pulmonary artery endothelial cells and suggested a new therapeutic strategy targeting EndoMT for the treatment of pulmonary arterial hypertension.