Methyltransferase‐like 14 (METTL14)‐mediated N6‐methyladenosine (m6A) Modification of Forkhead Box Protein 1 (FOXP1) Regulates Trophoblast Inflammation and Function via Transmembrane BAX Inhibitor Motif‐Containing 6 (TMBIM6)

Pre-eclampsia (PE) represents a serious pregnancy complication characterized by impaired trophoblast function. Although methyltransferase-like 14 (METTL14) has been implicated in PE pathogenesis and trophoblast dysfunction, its precise molecular mechanisms remain unclear. mRNA expression was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Immunoblot analysis was used for protein expression evaluation. Total N6-methyladenosine (m6A) RNA methylation was analyzed using an assay kit. Cell tube formation, invasion and colony formation were assessed by tube formation, transwell and colony formation assays, respectively. Interleukin-8 (IL-8), IL-1beta (IL-1β), and IL-6 levels were quantified by enzyme-linked immunosorbent assay (ELISA). The influence of METTL14 in forkhead box protein 1 (FOXP1) was tested by methylated RNA immunoprecipitation (MeRIP) and mRNA stabilization assays. The FOXP1/transmembrane BAX inhibitor motif-containing 6 (TMBIM6) relationship was validated by chromatin immunoprecipitation (ChIP) and luciferase assays. Total m6A methylation levels and METTL14 expression were significantly increased in placental samples of PE patients. Overexpression of METTL14 diminished cell colony formation, invasion, and tube formation abilities of human HTR-8/SVneo trophoblast cells and promoted their pro-inflammatory cytokine production. METTL14 epigenetically reduced FOXP1 expression via an m6A dependent mechanism. Re-expression of FOXP1 exerted a counteracting impact on METTL14-driven dysfunction and inflammation of HTR-8/SVneo cells. FOXP1 promoted TMBIM6 transcription, and METTL14 reduced TMBIM6 expression by FOXP1. FOXP1 regulated HTR-8/SVneo cell phenotypes and inflammation by TMBIM6. Our findings identify a new epigenetic mechanism, the METTL14/FOXP1/TMBIM6 axis, with the ability to affect trophoblast function and inflammation.