BACKGROUND: Acute kidney injury (AKI) is a common and severe complication of sepsis and represents an independent risk factor for mortality in septic patients. Despite its clinical significance, the mechanisms of sepsis-induced AKI (Sepsis-AKI) remain incompletely understood. This study investigates the role of methyltransferase like 14 (METTL14)-mediated m6A modification in regulating brain and muscle ARNT-like protein-1 (BMAL1) stability and its effect on tubular epithelial cell injury and ferroptosis.
METHODS: Human renal proximal tubular epithelial (HK-2) cells were treated with lipopolysaccharide (LPS) to establish an in vitro model of Sepsis-AKI. Cell proliferation and viability were assessed using EdU and CCK-8 assays; apoptosis was evaluated by TUNEL staining, and inflammatory cytokines Interleukin-6 (IL-6) and IL-1β were measured by ELISA. Ferroptosis indices were detected using corresponding kits. RT-qPCR and Western blotting were used to detect mRNA and protein expression. MeRIP and RIP assays were used to evaluate BMAL1 m6A modification and RNA-protein interaction. The stability of BMAL1 mRNA was determined using an Actinomycin D chase assay. A Sepsis-AKI model was established to examine the effect of METTL14 silencing on renal injury.
RESULTS: BMAL1 overexpression significantly alleviated LPS-induced apoptosis, inflammatory responses, and ferroptosis in HK-2 cells. Furthermore, METTL14 silencing reduced BMAL1 m6A modification, stabilized BMAL1 mRNA, and consequently improved HK-2 cell injury. In addition, YTHN6-methyladenosine RNA binding protein 1 (YTHDF1) was identified as the critical m6A reader mediating BMAL1 mRNA degradation. Consistently, in vivo experiments demonstrated that METTL14 knockdown mitigated Sepsis-AKI and ferroptosis in mice.
CONCLUSION: METTL14 enhanced BMAL1 m6A modification and promoted YTHDF1-mediated BMAL1 degradation, thereby facilitating ferroptosis and aggravating Sepsis-AKI.
