METTL14 deficiency impairs chondrogenic differentiation via m6A-dependent TRAF4 mRNA regulation in Kashin-Beck disease.

This study sought to establish the transcriptome-wide m6A methylome landscape in Kashin-Beck disease (KBD) chondrocytes and delineate the mechanistic contributions of the m6A methyltransferase METTL14 to KBD pathogenesis. Articular cartilage specimens were obtained from surgically confirmed Kashin-Beck disease (KBD) patients and normal controls. Multi-omics integration combined MeRIP-seq and RNA-seq to delineate m6A landscapes, supplemented by spectrophotometric m6A quantification. Differential expression of m6A machinery components was validated using qRT-PCR and immunoblotting. In chondrocyte models, lentiviral-mediated METTL14 knockdown (shRNA) and complementary overexpression were performed. METTL14-TRAF4 interaction was resolved via MeRIP and FISH. The therapeutic mechanism of quercetin was analyzed using CETSA and molecular docking. The methylome profiling of KBD articular cartilage revealed 1539 transcripts with differential m6A methylation patterns. Pathway enrichment analysis identified significant association with Wnt signaling and ubiquitin-mediated proteolysis pathways. Global m6A hypomethylation was accompanied by reduced expression of core methyltransferase complex components, including METTL14, YTHDC2, and WTAP. Mechanistic studies demonstrated that METTL14 directly binds to TRAF4 mRNA through an RNA-protein interaction. METTL14 knockdown significantly attenuated chondrogenic differentiation capacity, as evidenced by reduced expression of COL2A1, SOX9, TGF-β1, and PTHrP, while pharmacological activation via quercetin restored METTL14 expression and ameliorated KBD phenotypes. METTL14 is a central epigenetic modulator in KBD pathophysiology through TRAF4 coupled regulation of chondrocyte differentiation.