The Potential Molecular Mechanism Of MiR-29b Inhibition Of Collagen Synthesis In Pulmonary Arterial Hypertension

Objective: To investigate the effect of miR-29 b on collagen synthesis in PASMCs,and to explore the potential molecular mechanism of miR-29 b inhibiting collagen deposition of pulmonary arterial wall in the pathology of pulmonary arterial hypertension.Try to explore the potential targets of pulmonary arterial hypertension.Method: 1.Evaluated the effectiveness of animal models by measuring the right ventricular systolic pressure of rats.Observed and compared the changes of right ventricular systolic pressure,right ventricular hypertrophy index,the membrane ratio of pulmonary artery after monocrotaline treatment and miR-29 b mimic treatment.Analyzed the change of collagen deposition of the pulmonary vessel wall by Masson staining and Western Blot.2.To observe the effect of miR-29 b on collagen synthesis in PASMCs,we compared the expression changes of type I collagen and type III collagen which were detected by q RT-PCR and Western Blot in each group.3.To study the mechanism of miR-29 b on collagen synthesis,we searched for the target binding sites of miR-29 b and collagen through micro RNA database,and the accuracy of target sequences were detected by luciferase assay;at the same time,we screened the possible signaling pathways which were reported in the literature.After blocking the signal pathway,we analyzed the changes of collagen expression in each treatment group by Western Blot,and detected the expression level of miR-29 b by q RT-PCR and observed the interaction between target protein and miR-29 b by chromatin immunoprecipitation assay.Result: 1.Overexpression of miR-29 b can reduce the right ventricular systolic pressure,right ventricular hypertrophy index,the membrane ratio of pulmonary artery and deposition of collagen in pulmonary artery wall in animal model.2.miR-29 b can inhibit the collagen synthesis in pulmonary artery smooth muscle cells.3.After the mutation of type III collagen 3'-UTR,miR-29 b has no effect on collagen synthesis;MiR-29 b can block the phosphorylation of PI3K/AKT and inhibits the synthesis of I collagen.4.TGF-? inhibits the expression of miR-29 b through Smad3 signaling pathway.And the expression of miR-29 b in PASMCs has no statistical difference after the silence of Smad3.Conclusion: MiR-29 b could inhibit the collagen synthesis both in vitro and in vivo experiments.And the potential mechanisms are that: 1.miR-29 b inhibits the synthesis of collagen III by potential binding sites of collagen III 3'-UTR.2.miR-29 b regulates the synthesis of collagen I by the upstream TGF-?/Smad3 and the downstream PI3K/AKT signaling pathway.Thus it may partially reverse the process of PAH pathology.