METTL4 mediated-N6-methyladenosine promotes acute lung injury by activating ferroptosis in alveolar epithelial cells

Sepsis-induced acute lung injury has been deemed to be an life-threatening pulmonary dysfunction caused by a dysregulated host response to infection. The modification of N6-Methyladenosine (m6A) is implicated in several biological processes, including mitochondrial transcription and ferroptosis. Ferroptosis is an iron-dependent type of programed cell death, which plays a role in sepsis-induced acute lung injury (ALI). Nuclear factor erythroid 2related factor 2 (Nrf2) is a crucial regulator of intracellular oxidative homeostasis, linked to ferroptosis resistance. This research aims to explore the effect of m6A in ferroptosis in sepsis-induced ALI. First, we found a timedependent dynamic alteration on pulmonary methylation level during sepsis-induced ALI. We identified METTL4 as a differentially expressed gene in ALI mice using m6A sequencing and RNA-sequencing, and revealed the methylation of several ferroptosis related genes (Nrf2). Thus, we generated METTL4 deficiency mice and found that METTL4 knockdown alleviated ferroptosis, as evidenced by lipid ROS, MDA, Fe2+, as well as alterations in GPX4 and SLC7A11 protein expression. Consistently, we found that METTL4 silencing could decrease ferroptosis sensitivity in LPS-induced TC-1 cells. Furthermore, both the dual-luciferase reporter assay and rescue experiments indicated that METTL4 mediated the N6-methyladenosine of Nrf2 3 ' UTR, then YTHDF2 binded with the m6A site, promoting the degradation of Nrf2. In conclusion, we revealed that METTL4 promoted alveolar epithelial cells ferroptosis in sepsis-induced lung injury via N6-methyladenosine of Nrf2, which might provide a novel approach to therapeutic strategies for sepsis-induced ALI.