METTL14 knockdown attenuates neuron injury and improves function recovery after spinal cord injury via regulating FGF21 in a m6A-IGF2BP1 dependent mechanism.

Background: Fibroblast growth factor 21 (FGF21) and Methyltransferase-like 14 (METTL14) have been identified to be involved in spinal cord injury (SCI). However, whether FGF21 functioned in SCI via METTL14-induced N6-methyladenosine (m6A) modification remains unclear.

Materials and methods: PC12 cells were exposed to lipopolysaccharide (LPS) in vitro. qRT-PCR and western blotting analyses were applied to detect the mRNA and protein levels of METTL14, FGF21 and Insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1). The CCK-8 assay, EdU assay, flow cytometry and ELISA analysis were used to conduct in vitro functional analyses. Cell ferroptosis was assessed by measuring the levels of Fe2+, reactive oxygen species, glutathione and related regulators. The N6-methyladenosine (m6A) modification profile was analyzed by methylated RNA immunoprecipitation (MeRIP) assay. The interaction between IGF2BP1 and FGF21 was validated using RIP assay. SCI animal models were constructed for in vivo analysis.

Results: Levels of FGF21 were decreased in LPS-induced PC12 cells. Functionally, FGF21 overexpression reversed LPS-induced proliferation inhibition, apoptosis, ferroptosis and inflammation in PC12 cells. Mechanistically, METTL14 induced FGF21 m6A modification in SCI cell models, and m6A-binding protein IGF2BP1 was involved in regulating FGF21 expression by METTL14. METTL14 silencing abolished LPS-induced neuronal apoptosis, inflammation and ferroptosis via regulating FGF21. Moreover, METTL14 silencing improved neuronal injury in SCI rat models by modulating FGF21 expression.

Conclusions: METTL14 knockdown attenuates neuron injury and improves function recovery after SCI via up-regulating FGF21 in an m6A-IGF2BP1 dependent mechanism, suggesting a useful target for SCI recovery.