MicroRNA‐144‐3p controls the apoptosis of pulmonary artery endothelial cells in pulmonary arterial hypertension via the BMPR2/Smad4 signaling pathway

Abstract Background This study was to determine the molecular mechanism of miR‐144‐3p in the treatment of pulmonary arterial hypertension (PAH). Methods Luciferase assays detected the binding site of miR‐144‐3p. Quantitative reverse transcription‐polymerase chain reaction (PCR) measured the expression of downstream genes of Smad4 in pulmonary artery endothelial cells (PAECs). Cell apoptosis was analysed by fluorescence activated cell sorting (FACS) analysis. In a monocrotaline‐induced rat PAH model, the integrity of PAECs was detected by hematoxylin eosin (H&E) staining, immunohistochemistry, and immunofluorescence. The protein expression of the bone morphogenetic protein receptor 2 (BMPR2)/Smad4 signaling pathway was analysed by Western blotting. Results MiR‐144‐3p targeted Smad4 directly and down‐regulated the expression of α‐smooth muscle actin (SMA), Connective tissue growth factor (CTGF) and c‐myelocytomatosis (MYC) in PAECs. There was a significant change in the apoptosis of PAECs transfected with miR‐144‐3p. After transfection, the phosphorylation of Smad4 decreased only at 24 h. The integrity of PAECs was improved by miR‐144‐3p. There was a down‐regulation in BMPR2, Smad1/5 and p‐Smad1/5 in the PAH group. The fold change in Smad4 and p‐Smad4 expression decreased significantly in the PAH‐miR group. Moreover, we observed decreased α‐SMA, CTGF and c‐MYC expression and an up‐regulation of vascular endothelial (VE)‐cadherin. Conclusions MiR‐144‐3p modulates apoptosis and phenotype switching of PAECs via phosphorylation of the BMPR2/Smad4 signaling pathway.