METTL3/FOSL1-associated inflammatory and autophagy-related responses involve m6A-related regulation in sepsis-induced acute kidney injury.

Sepsis-induced acute kidney injury (S-AKI) is marked by tubular damage, inflammation, and dysregulated autophagy. N6-methyladenosine (m6A) RNA modification has emerged as an important regulator of mRNA stability and cellular stress responses; however, its involvement and related regulatory mechanisms in S-AKI remain incompletely understood. Human HK-2 proximal tubular epithelial cells were stimulated with LPS to establish an in vitro S-AKI model, while CLP-induced septic C57BL/6 J mice were used as an in vivo model. Global m6A levels, METTL3, and FOSL1 expression were assessed by ELISA, qRT-PCR, and Western blot. Functional roles of METTL3 and FOSL1 were evaluated using siRNA-mediated knockdown, plasmid-driven overexpression, and pharmacological inhibitors. MeRIP-qPCR and RIP-qPCR were performed to evaluate m6A-related enrichment and the association between METTL3 and FOSL1 mRNA. Inflammatory cytokines, autophagy-related markers, NF-κB and mTOR signaling alterations, renal function, and histopathological changes were assessed. LPS stimulation increased global m6A levels and upregulated METTL3 and FOSL1 expression in HK-2 cells, accompanied by enhanced inflammatory responses and autophagy-related alterations. FOSL1 knockdown attenuated LPS-induced inflammation and autophagy-related changes, whereas METTL3 overexpression increased FOSL1 expression and exacerbated these effects. Further analyses indicated that METTL3 was associated with FOSL1 mRNA stability in an m6A-related manner. Alterations in FOSL1 expression were associated with changes in NF-κB and mTOR-related signaling responses under S-AKI conditions. In CLP-induced S-AKI mice, METTL3 knockdown reduced FOSL1 expression, alleviated inflammatory responses and autophagy-related alterations, and improved renal function and histopathological injury. Our findings suggest that METTL3/FOSL1-associated regulatory responses may participate in S-AKI through m6A-related regulation, contributing to inflammatory and autophagy-related alterations. These findings provide further insight into the involvement of m6A-related regulation in the pathogenesis of S-AKI.