GCN2 Regulates ATF3-p38 MAPK Signaling Transduction in Pulmonary Veno-Occlusive Disease

Pulmonary veno-occlusive disease (PVOD) is a fatal disease of pulmonary vascular lesions leading to right heart failure. Heritable PVOD (hPVOD) is related to biallelic mutation of EIF2AK4 (encoding GCN2), but its molecular mechanism remains unclear. In this study, we aimed to investigate the pathogenesis of PVOD and to find potential drug targets for PVOD. GCN2 dysfunction led to an enhanced transcription of collagen I gene (col1a1 and col1a2) through decreasing ATF3-dependent p38 phosphorylation inhibition in PVOD, which promotes the collagen I synthesis in pulmonary arterial smooth muscle cells (PASMCs) and eventually leads to increased collagen deposition in pulmonary artery. Four GCN2 knockout (KO) cell lines (exon 15 or 33 mutation) were successfully constructed by epiCRISPR system. Two induced pluripotent stem cells (iPSCs) were generated by reprogramming peripheral blood mononuclear cells (PBMCs) of PVOD patient. It was also comfirmed that GCN2 dysfunction could lead to increased expression of collagen I in lateral plate mesoderm lineage-smooth muscle cells (LM-SMCs) differentiated from both GCN2 KO cell lines and iPSCs. SB203580 (a specific inhibitor of p38) improved hemodynamics and pulmonary vascular remodeling in mitomycin C (MMC)-induced PVOD rats by right ventricle echocardiography. On the whole, we proposed that GCN2 deficiency decreased ATF3-dependent p38 phosphorylation inhibition in PVOD development and suggested a potential therapeutic reagent of SB203580 for the treatment of the disease.