Blocking the Spinal Fbxo3/CARM1/K+ Channel Epigenetic Silencing Pathway as a Strategy for Neuropathic Pain Relief

Abstract

Many epigenetic regulators are involved in pain-associated spinal plasticity. Coactivator-associated arginine methyltransferase 1 (CARM1), an epigenetic regulator of histone arginine methylation, is a highly interesting target in neuroplasticity. However, its potential contribution to spinal plasticity-associated neuropathic pain development remains poorly explored. Here, we report that nerve injury decreased the expression of spinal CARM1 and induced allodynia. Moreover, decreasing spinal CARM1 expression by Fbxo3-mediated CARM1 ubiquitination promoted H3R17me2 decrement at the K⁺ channel promoter, thereby causing K⁺ channel epigenetic silencing and the development of neuropathic pain. Remarkably, in naïve rats, decreasing spinal CARM1 using CARM1 siRNA or a CARM1 inhibitor resulted in similar epigenetic signaling and allodynia. Furthermore, intrathecal administration of BC-1215 (a novel Fbxo3 inhibitor) prevented CARM1 ubiquitination to block K⁺ channel gene silencing and ameliorate allodynia after nerve injury. Collectively, the results reveal that this newly identified spinal Fbxo3-CARM1-K⁺ channel gene functional axis promotes neuropathic pain. These findings provide essential insights that will aid in the development of more efficient and specific therapies against neuropathic pain.

Keywords: CARM1; Fbxo3; Histone arginine methylation; neuropathic pain; spinal.