PRMT2-mediated upregulation of miR-323-3p in sensory neurons promotes trigeminal neuropathic pain by targeting Kv2.1 channels

Herein, we show a molecular pathway driven by an evolutionarily conserved microRNA (miRNA) in sensory neurons to control neuropathic pain. By employing high-throughput sequencing analysis, we find that miRNA-323-3p (miR-323-3p) exhibits the most significant upregulation in injured trigeminal ganglia (TGs). Local inhibition of miR-323-3p in injured TGs suppresses established trigeminal neuropathic pain but has no effect on inflammatory pain. Mechanistically, nerve injury upregulates the protein expression of protein arginine methyltransferase 2 (PRMT2), which promotes asymmetric dimethylation of H3R8, thereby facilitating the binding of the transcription factor forkhead box A2 (FOXA2) to the miR-323-3p promoter and resulting in the upregulation of miR-323-3p expression. Furthermore, the increased miR-323-3p expression induces significant reductions in Kv2.1 protein expression and channel currents, resulting in TG neuronal hyperexcitability. Conversely, the downregulation of miR-323-3p in injured TGs restores the decreased Kv2.1 expression and attenuates nerve-injury-induced mechanical hypersensitivity. The PRMT2/FOXA2/miR-323-3p/Kv2.1 signaling axis in sensory neurons may offer therapeutic targets in neuropathic pain management.