METTL3-mediated m(6)A modification of HMGA2 mRNA promotes subretinal fibrosis and epithelial–mesenchymal transition

Subretinal fibrosis is a major cause of the poor visual prognosis for patients with neovascular age-related macular degeneration (nAMD). Myofibroblasts originated from retinal pigment epithelial (RPE) cells through epithelial–mesenchymal transition (EMT) contribute to the fibrosis formation. N(6)-Methyladenosine (m(6)A) modification has been implicated in the EMT process and multiple fibrotic diseases. The role of m(6)A modification in EMT-related subretinal fibrosis has not yet been elucidated. In this study, we found that during subretinal fibrosis in the mouse model of laser-induced choroidal neovascularization, METTL3 was upregulated in RPE cells. Through m(6)A epitranscriptomic microarray and further verification, high-mobility group AT-hook 2 (HMGA2) was identified as the key downstream target of METTL3, subsequently activating potent EMT-inducing transcription factor SNAIL. Finally, by subretinal injections of adeno-associated virus vectors, we confirmed that METTL3 deficiency in RPE cells could efficiently attenuate subretinal fibrosis in vivo. In conclusion, our present research identified an epigenetic mechanism of METTL3–m(6)A–HMGA2 in subretinal fibrosis and EMT of RPE cells, providing a novel therapeutic target for subretinal fibrosis secondary to nAMD.