YTHDF1 Regulates Pulmonary Hypertension through Translational Control of MAGED1

Rationale: Posttranscriptional modifications are implicated in vascular remodeling of pulmonary hypertension (PH). m6A (N6-methyladenosine) is an abundant RNA modification that is involved in various biological processes. Whether m6A RNA modification and m6A effector proteins play a role in pulmonary vascular remodeling and PH has not been demonstrated.Objectives: To determine whether m6A modification and m6A effectors contribute to the pathogenesis of PH.Methods: m6A modification and YTHDF1 expression were measured in human and experimental PH samples. RNA immunoprecipitation analysis and m6A sequencing were employed to screen m6A-marked transcripts. Genetic approaches were employed to assess the respective roles of YTHDF1 and MAGED1 in PH. Primary cell isolation and cultivation were used for function analysis of pulmonary artery smooth muscle cells (PASMCs).Measurements and Main Results: Elevated m6A levels and increased YTHDF1 protein expression were found in human and rodent PH samples as well as in hypoxic PASMCs. The deletion of YTHDF1 ameliorated PASMC proliferation, phenotype switch, and PH development both in vivo and in vitro. m6A RNA immunoprecipitation analysis identified MAGED1 as an m6A-regulated gene in PH, and genetic ablation of MAGED1 improved vascular remodeling and hemodynamic parameters in SU5416/hypoxia mice. YTHDF1 recognized and promoted translation of MAGED1 in an m6A-dependent manner that was absent in METTL3-deficient PASMCs. In addition, MAGED1 silencing inhibited hypoxia-induced proliferation of PASMCs through downregulating PCNA.Conclusions: YTHDF1 promotes PASMC proliferation and PH by enhancing MAGED1 translation. This study identifies the m6A RNA modification as a novel mediator of pathological changes in PASMCs and PH.