Hydroxymethylation of microRNA-365-3p Regulates Nociceptive Behaviors via Kcnh2

Abstract

DNA 5-hydroxylmethylcytosine (5hmC) catalyzed by ten-eleven translocation methylcytosine dioxygenase (TET) occurs abundantly in neurons of mammals. However, the in vivo causal link between TET dysregulation and nociceptive modulation has not been established. Here, we found that spinal TET1 and TET3 were significantly increased in the model of formalin-induced acute inflammatory pain, which was accompanied with the augment of genome-wide 5hmC content in spinal cord. Knockdown of spinal TET1 or TET3 alleviated the formalin-induced nociceptive behavior and overexpression of spinal TET1 or TET3 in naive mice produced pain-like behavior as evidenced by decreased thermal pain threshold. Furthermore, we found that TET1 or TET3 regulated the nociceptive behavior by targeting microRNA-365-3p (miR-365-3p). Formalin increased 5hmC in the miR-365-3p promoter, which was inhibited by knockdown of TET1 or TET3 and mimicked by overexpression of TET1 or TET3 in naive mice. Nociceptive behavior induced by formalin or overexpression of spinal TET1 or TET3 could be prevented by downregulation of miR-365-3p, and mimicked by overexpression of spinal miR-365-3p. Finally, we demonstrated that a potassium channel, voltage-gated eag-related subfamily H member 2 (Kcnh2), validated as a target of miR-365-3p, played a critical role in nociceptive modulation by spinal TET or miR-365-3p. Together, we concluded that TET-mediated hydroxymethylation of miR-365-3p regulates nociceptive behavior via Kcnh2.

METTL3 regulates inflammatory pain by modulating m6A‐dependent pri‐miR‐365‐3p processing

“…Recently, Alarcon and colleagues demonstrated that m 6 A modification could mark pri-miRNA for processing by recognizing DGCR8 in a METTL3-dependent manner, 18 indicating that altered METTL3-mediated m 6 A modification might be responsible for the aberrant expression of miRNAs in many biological processes. 21 It is possible that miR-365-3p is targeted by two different regulators during inflammatory pain condition. We found that increased METTL3 induced by CFA could regulate pri-miRNA-365-3p processing in an m 6 A-dependent manner.…”

Epigenetic regulation mechanisms of microRNA expression

“…Recent studies revealed that 5hmC is consistently found at significantly reduced levels (more than 50% reduction, p ≤ 0.01) in various solid tumors (73)(74)(75). Recently, using a mouse model, Pan et al (76) studied the role of hydroxymethylation in neurophysiological processes and provided the first evidence that miRNAs can be regulated by hydroxymethylation of their promoters. Working with a mouse model of formalin-induced acute inflammatory pain, they observed a significant increase in 5hmC and a decrease in 5mC in the miR-365-3p promoter that resulted in the enhancement of miR-365-3p transcription and in the subsequent increase of miR-365-3p expression (Figure 4).…”

Tet1-dependent epigenetic modification of BDNF expression in dorsal horn neurons mediates neuropathic pain in rats

“…Conversely, Tet1-knockout mice present learning deficiencies and memory retention accompanied by extensive methylation of cytosine in the promoters of learning/memory-related genes8. Recently, a study reported that spinal Tet family are essential for inflammatory nociception transmission9. These evidence implying that analogous forms of synaptic plasticity caused by the Tet1-mediated DNA demethylation-modifying 5 mC/5 hmC enrichment in pain-associated genes may operate at spinal sites to participate in neuropathic pain processing.…”