Pan Zhiqiang, Zhang Ming, Ma Tao, Xue Zhou-Ya, Li Guo-Fang, Hao Ling-Yun, Zhu Li-Jiao, Li Yan-Qiang, Ding Hai-Lei, Cao Jun-Li
Jiangsu Province Key Laboratory of Anesthesiology and Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical College, Xuzhou 221004, China, and
Jiangsu Province Key Laboratory of Anesthesiology and Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical College, Xuzhou 221004, China, and.
J Neurosci. 2016 Mar 2;36(9):2769-81. doi: 10.1523/JNEUROSCI.3474-15.2016.
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.
Mounting evidence indicates that epigenetic modifications in the nociceptive pathway contribute to pain processes and analgesia response. Here, we found that the increase of 5hmC content mediated by TET1 or TET3 in miR-365-3p promoter in the spinal cord is involved in nociceptive modulation through targeting a potassium channel, Kcnh2. Our study reveals a new epigenetic mechanism underlying nociceptive information processing, which may be a novel target for development of antinociceptive drugs.
由十一-易位甲基胞嘧啶双加氧酶（TET）催化产生的DNA 5-羟甲基胞嘧啶（5hmC）大量存在于哺乳动物的神经元中。然而，TET失调与伤害性感受调节之间的体内因果关系尚未确立。在此，我们发现，在福尔马林诱导的急性炎性疼痛模型中，脊髓中的TET1和TET3显著增加，同时脊髓中全基因组5hmC含量也随之增加。敲低脊髓中的TET1或TET3可减轻福尔马林诱导的伤害性行为，而在未处理的小鼠中过表达脊髓TET1或TET3则会产生类似疼痛的行为，热痛阈值降低即为证据。此外，我们发现TET1或TET3通过靶向微小RNA-365-3p（miR-365-3p）来调节伤害性行为。福尔马林增加了miR-365-3p启动子中的5hmC，这被TET1或TET3的敲低所抑制，并在未处理的小鼠中被TET1或TET3的过表达所模拟。下调miR-365-3p可预防福尔马林或脊髓TET1或TET3过表达诱导的伤害性行为，而过表达脊髓miR-365-3p则可模拟该行为。最后，我们证明了一种钾通道，电压门控EAG相关亚家族H成员2（Kcnh2），被确认为miR-365-3p的靶点，在脊髓TET或miR-365-3p对伤害性感受的调节中起关键作用。我们共同得出结论，TET介导的miR-365-3p羟甲基化通过Kcnh2调节伤害性行为。
越来越多的证据表明，伤害性感受通路中的表观遗传修饰有助于疼痛过程和镇痛反应。在此，我们发现脊髓中TET1或TET3介导的miR-365-3p启动子中5hmC含量的增加通过靶向钾通道Kcnh参与伤害性感受调节。我们的研究揭示了伤害性信息处理背后一种新的表观遗传机制，这可能是开发抗伤害性药物的一个新靶点。
