LncRNAH19 acts as a ceRNA of let-7g to facilitate EndMT in hypoxic pulmonary hypertension via regulating TGF-β signalling pathway

Abstract Background Hypoxic pulmonary hypertension (HPH) is a challenging lung arterial disorder with remarkably high incidence and mortality rates, and the efficiency of current HPH treatment strategies is unsatisfactory. Endothelial-to-mesenchymal transition (EndMT) in the pulmonary artery plays a crucial role in HPH. Previous studies have shown that lncRNA-H19 (H19) is involved in many cardiovascular diseases by regulating cell proliferation and differentiation but the role of H19 in EndMT in HPH has not been defined. Methods In this research, the expression of H19 was investigated in PAH human patients and rat models. Then, we established a hypoxia-induced HPH rat model to evaluate H19 function in HPH by Echocardiography and hemodynamic measurements. Moreover, luciferase reporter gene detection, and western blotting were used to explore the mechanism of H19. Results Here, we first found that the expression of H19 was significantly increased in the endodermis of pulmonary arteries and that H19 deficiency obviously ameliorated pulmonary vascular remodelling and right heart failure in HPH rats, and these effects were associated with inhibition of EndMT. Moreover, an analysis of luciferase activity indicated that microRNA-let-7g (let-7g) was a direct target of H19. H19 deficiency or let-7g overexpression can markedly downregulate the expression of TGFβR1, a novel target gene of let-7g. Furthermore, inhibition of TGFβR1 induced similar effects to H19 deficiency. Conclusions In summary, our findings demonstrate that the H19/let-7g/TGFβR1 axis is crucial in the pathogenesis of HPH by stimulating EndMT. Our study may provide new ideas for further research on HPH therapy in the near future.