METTL3-Dependent YTHDF2 Mediates TSC1 Expression to Regulate Alveolar Epithelial Mesenchymal Transition and Promote Idiopathic Pulmonary Fibrosis.

Diffuse, progressive interstitial lung disease with few treatment options and low survival rates is known as idiopathic pulmonary fibrosis (IPF). Alveolar epithelial cell damage and dysfunction are the main features of IPF. TSC1 has been documented to exert a pivotal function in governing cellular growth, proliferation, and ontogenesis. This work investigated TSC1's function and mechanism in IPF. Mice were given BLM to cause pulmonary fibrosis, and A549 cells underwent epithelial mesenchymal transition (EMT) in response to TGF-β1. According to the data, TSC1 expression was reduced in IPF. Overexpression of TSC1 was established by adenopathy-associated virus in vivo and adenovirus in vitro to significantly block the EMT process. Besides, the findings from the RNA-sequencing analysis indicate that overexpression of TSC1 mitigated the EMT process by suppressing the activation of the AKT/mTOR pathway via downregulation of ACTN4 expression. To examine the upstream regulatory mechanism, we employed the SRAMP database to predict m6A modification of TSC1 mRNA, followed by verification of m6A modification levels and expression using MERIP-qPCR, Dot blot, RT-qPCR, and WB. The results indicated a high degree of m6A modification in TSC1 mRNA in pulmonary fibrosis. The expression of METTL3 was further found to be significantly elevated. METTL3 knockdown impeded EMT progression. METTL3 inhibits TSC1 expression by increasing TSC1 m6A modification through the reading protein YTHDF2. In conclusion, our study elucidated that the METTL3/YTHDF2/TSC1 signaling axis activates the AKT/mTOR pathway to promote the development of IPF. This study provides potential molecular-level therapeutic targets for IPF disease.