Dynamic Arginine Methylation of Tumor Necrosis Factor (TNF) Receptor-associated Factor 6 Regulates Toll-like Receptor Signaling

Arginine methylation is a common post-translational modification, but its role in regulating protein function is poorly understood. This study demonstrates that, TNF receptor-associated factor 6 (TRAF6), an E3 ubiquitin ligase involved in innate immune signaling, is regulated by reversible arginine methylation in a range of primary and cultured cells. Under basal conditions, TRAF6 is methylated by the methyltransferase PRMT1, and this inhibits its ubiquitin ligase activity, reducing activation of toll-like receptor signaling. In response to toll-like receptor ligands, TRAF6 is demethylated by the Jumonji domain protein JMJD6. Demethylation is required for maximal activation of NF-kappa B. Loss of JMJD6 leads to reduced response, and loss of PRMT1 leads to basal pathway activation with subsequent desensitization to ligands. In human primary cells, variations in the PRMT1/JMJD6ratiosignificantlycorrelatewithTRAF6methylation, basal activation of NF-kappa B, and magnitude of response to LPS. Reversible arginine methylation of TRAF6 by the opposing effects of PRMT1 and JMJD6 is, therefore, a novel mechanism for regulation of innate immune pathways.