The miR-182/Myadm axis regulates hypoxia-induced pulmonary hypertension by balancing the BMP- and TGF-β-signalling pathways in an SMC/EC-crosstalk-associated manner

We recently identified oncologic miR-182 as a new regulator of pulmonary artery hypertension (PAH) that targets myeloid-associated differentiation marker (Myadm), which is expressed in bone marrow stem cells and multipotent progenitors. Both miR-182 and Myadm are expressed in the cardiopulmonary system and correlated with the balance between the bone morphogenetic protein (BMP) and the transforming growth factor (TGF)-β signalling pathways, which are disturbed in PAH. We hypothesize that miR-182/Myadm are involved in BMP-TGF-β-signalling way in PAH. Hypoxia triggered pathological progression in cardiopulmonary PAH in vivo and in vitro; these changes were accompanied by strongly dowregulated BMP/SMAD1/5/8 expression and enhanced TGF-β/SMAD2/3 signalling pathway, favouring SMAD4/SMAD2 transcript formation and inhibiting the PAH negative regulator Id1 expression. miR-182 gain-of-function significantly inhibited the pathological progression in hypoxia-induced PAH (HPH) in vivo and in vitro, with a restoration of the balance in BMP-TGF-β signalling pathway. This recovery was abrogated by overexpression of Myadm. Conversely, loss-of-function of miR-182 increased the pathological progression of HPH followed by severe disturbance of BMP and TGF-β signal transduction and reduced Id1 expression, which was restored by Myadm knockdown. We also showed that the miR-182/Myadm relate BMP-TGF-β pathway is associated with NOS3/NO/cGMP via the crosstalk between endothelial cells and smooth muscle cells. Our findings further support the therapeutic significance of miR-182/Myadm in PAH via the balance of BMP- and TGF-β-associated mechanisms.