The Role And Mechanism Of YTHDF1 In Pulmonary Vascular Remodeling By Regulating The Phenotype Switching Of Smooth Muscle Cells

Background:Pulmonary Hypertension is an irreversible disease characterized by pulmonary vascular remodeling,lumen stenosis and progressive increase of pulmonary vascular resistance,ultimately leading to right heart failure and premature death.According to the classification of World Health Organization,PH are divided into the following five group:Group 1,pulmonary arterial hypertension(idiopathic and familial PAH);group2,PH associated with left heart disease;group 3,PH with chronic hypoxia and/or chronic lung disease;group 4,PH with pulmonary artery obstructive diseases;group 5,PH with unknown mechanism and(or)multiple mechanisms.Although endothelin receptor blockers,prostanoids and NO vasodilators are the main treatments currently,no medication can rescue or prevent PH progression.Thus,it is necessary to screen for an effective target for clinical therapy.Additionally,certification of the causes about PH associated death is a difficult task in forensic application for unability to measure pulmonary arterial pressure after death,complex etiologies and lack of specificity of pathological features.So,screening for biological markers is important for evaluation on causes of PH associated death.N~6-methyladenosine is the most prevalent methylation modification onRNA,which accounts for 80%of allRNA modification.Methytransferases(m~6A writers)and demethylases(m~6A erasers)modify m~6A onRNAs in a dynamic regulation.The different downstream effects ofRNAs with m~6A modification are mainly determined by m~6A readers(YTH domain family members).It has been reported that YTHDF1 and YTHDF3 can promoteRNA translation and protein expression through recruiting translation initial factor on transcripts and transporting to ribosome.While YTHDF2can promoteRNA degradation through recognizing the m~6A modifiedRNAs and transportingRNAs into processing body in cytoplasm.M~6ARNA modification plays an important role in embryogenesis,tumorigenesis and metastasis,lipid metabolism and cell phenotype switching in a transcriptional independent manner.However,whether m~6ARNA modification contribute to PH and pulmonary vascular remodeling has not been demonstrated.Objects:1.To investigate the relevance between m~6A modification and PH.2.To study the role of m~6A modification and m~6A binding protein YTHDF1 in pulmonary vascular remodeling and PH.3.To identify the target gene regulated by m~6A modification and YTHDF1 in PH.4.To determine the role and mechanism of target gene involved in PH and pulmonary vascular remodeling.Results:1.The level of m~6A modification and the expression of YTHDF1 protein were higher in the lung tissues of IPAH patients and mice as well as in the pulmonary arterioles of rat.2.The genetic ablation of YTHDF1 alleviated PH development and improved right heart function of PH mice.3.Elevated m~6A levels and higher YTHDF1 protein expression were found in PASMCs(pulmonary artery smooth muscle cells)treated with hypoxia or other pro- PH factors,and the deletion of YTHDF1 improved the PASMCs phenotype switching induced by hypoxia.4.The m~6A modification and protein expression of MAGED1 were significantly enriched in human and rodent PH samples as well as in hypoxic PASMCs.5.YTHDF1 recognized MAGED1 mRNA modified by m~6A and promoted MAGED1 mRNA translation.6.MAGED1 knockout attenuated the progression of PH and inhibited the phenotype switching of PASMCs induced by hypoxia.Conclusion:YTHDF1 regulates PASMCs phenotype switching through mediating MAGED1translation in the development of PH,the levels of m~6A modification and YTHDF1protein expression can be a potential biomarker in forensic evaluation on causes of PH associated death.