1,25(OH)2D3 attenuates pulmonary arterial hypertension via microRNA-204 mediated Tgfbr2/Smad signaling

Pulmonary arterial hypertension (PAH) is a devastating disease characterized by high pulmonary artery pressure. It is reported that microRNA-204 (miR-204) plays an important role in the development of PAH. Calcitriol [1,25-dihydroxyvitamin D3, 1,25(OH)₂D₃] mediates multiple pathophysiological processes. The aim of the current study was to explore the role of 1,25(OH)₂D₃ in PAH. PAH was induced in rats and rat pulmonary arterial endothelial cells (PAECs) were isolated as in vitro PAH model. The mean pulmonary artery pressure, morphologic changes, and expressions of transforming growth factor-beta1 (Tgfbr2), Smad2/7, alpha smooth muscle actin (α-SMA), and p21 were then measured. Furthermore, the effect of 1,25(OH)₂D₃ on rat PAECs with or without hypoxia treatment was also assessed by measuring the proliferation, migration, and cell cycle distribution of PAECs. The potential targets of miR-204 were also predicted and validated with a dual-luciferase reporter system. Then the role of miR-204 and Tgfbr2 in the anti-PAH effect of 1,25(OH)₂D₃ was further explored by modulating the expression of the two genes. The overall pulmonary hypertension and hypoxia-induced proliferation and migration of PAECs were attenuated by administration of 1,25(OH)₂D₃, which was associated with the suppressed expressions of Tgfbr2, α-SMA, and Smad7 and induced expressions of miR-204, p21 and Smad2 both in vitro and in vivo. Moreover, the luciferase reporter assay identified Tgfbr2 as a novel direct target of miR-204. Both overexpression of miR-204 and inhibition of Tgfbr2 would strengthen the effect of 1,25(OH)₂D₃ administration. Findings outlined in the current study demonstrated that 1,25(OH)₂D₃ was a promising therapeutic modality for treatment of PAH, function of which was exerted through miR-204 mediated Tgfbr2 signaling.