METTL3-m⁶A-LOXL2 Axis Post-Transcriptionally Fine-Tunes Macrophage Migration and Invasion

While the RNA modification N⁶-methyladenosine (m⁶A) is known to influence immune cell function, its specific role in regulating macrophage migration and invasion remains poorly defined. This study aimed to elucidate the function and mechanism of the core m⁶A methyltransferase METTL3 in the migratory and invasive capacities of macrophages.

A macrophage-specific METTL3-knockdown model was established. The functional effects of METTL3 deficiency were systematically evaluated using migration, invasion, phagocytosis, and polarization assays. Subsequent transcriptome sequencing (RNA-seq) and methylated RNA immunoprecipitation-quantitative PCR (MeRIP-qPCR) were employed to identify the key differentially expressed gene, lysyl oxidase-like 2 (LOXL2). This mechanistic link was ultimately confirmed through functional rescue experiments and reconstitution assays.

METTL3 deficiency significantly increased the migratory and invasive capacities of macrophages but attenuated their phagocytic activity, promoting a shift toward an M2-like polarization state. Mechanistically, METTL3 knockdown reduced m⁶A modification at a specific site of LOXL2 mRNA, thereby decreasing its RNA stability and leading to decreased expression. Importantly, this phenotype was validated through functional inhibition assays. Reconstitution of LOXL2 in METTL3-deficient macrophages substantially reversed the enhanced migratory and invasive phenotypes.

This study reveals a novel METTL3-m⁶A-LOXL2 signaling axis that posttranscriptionally fine-tunes macrophage migration and invasion by regulating gene expression. These findings provide a mechanistic explanation for the functional dynamics of macrophage migration and invasion and underscore that m⁶A modification is a key regulator of innate immune cell behavior.