microRNA30b/96/182调控电压门控钠离子通道1.7参与神经病理性疼痛的作用机制

SCN9A gene encodes the ? subunit of sodium channel 1.7（Nav1.7）, which plays an important role in neuropathic pain. Its mutation has a close relation with three congenital diseases of paresthesia. MicroRNAs widely expresse in organisms and are closely related to the pain. Bioinformatics analysis revealed that miR-30b/96/182 are closely related to SCN9A.Therefore, we hypothesized that perpheral nerve injury might down regulate miR-30b/96/182 expression which make SCN9A lose post-transcriptional suppression. Nav1.7 expression increasing enhances neuronal excitability, causing the release of neurotransmitters such as substance P and glutamate in spinal cord. Signal transduction ultimately results in pain. In the present study, a rat neuropathic pain model established by the sciatic nerve injury are used. We will examine the relationship between SCN9A and miR-30b/96/182 by overexpression or knocking down miR-30b/96/182. To determine the analgesic effect of miR-30b/96/182, we detect changes of Nav1.7, neuronal electrophysiological and hyperalgesia by building viral vectors carrying miR-30b/96/182, which provide new ideas for the pain treatment.

SCN9A基因编码的钠离子通道1.7亚基（Nav1.7）在神经病理性疼痛的发生发展中具有重要作用。减少Nav1.7表达量及活性可降低神经元的兴奋性，缓解疼痛。microRNA广泛表达于生物体内，与疼痛密切相关。课题组通过生物信息学查找发现miR-30b/96/ 182与SCN9A密切相关。据此提出假说: 外周神经损伤，miR-30b/96/182表达下调，SCN9A 转录后抑制减少，Nav1.7表达增加，神经元兴奋性增强，引起脊髓P物质和谷氨酸等神经递质释放增加，进一步传递信号，最终导致疼痛。本项目拟建立坐骨神经分支选择性损伤疼痛模型，通过过表达或沉默miR-30b/96/182表达，探讨其与SCN9A的作用关系。通过构建病毒载体，上调miR-30b/96/182，观察Nav1.7和神经元电生理的变化及痛敏情况，明确miR-30b/96/182的镇痛效应，为疼痛治疗提供新思路。

该项目计划对SCN9A基因编码的钠离子通道1.7亚基（Nav1.7）的靶向microRNA调控功能在神经病理性疼痛的发生发展中的参与机制展开研究。自获得国家基金委资助后，该项目进展顺利，相继在国内外著名杂志发表相关成果。体外实验部分，首先我们利用双荧光素报告酶基因检测方法研究并验证了三种预测靶向microRNA30b/96/182中microRNA30b/182与SCN9A基因编码的钠离子通道1.7亚基（Nav1.7）存在预期靶标关系。应用原代培养DRG神经元细胞，通过构建病毒载体，细胞转染和谷氨酸刺激等方式，检测出microRNA30b/182与Nav1.7存在负向调控的关系。体内实验部分，应用大鼠神经病理性疼痛模型，利用蛋白免疫印记、实时定量PCR和电生理等方法，检测出疼痛模型大鼠DRG 中microRNA30b/182表达下调，继而对SCN9A 转录后抑制减少，导致Nav1.7表达增加，神经元兴奋性增强，进一步传递信号，最终导致疼痛。而当在神经病理性疼痛模型大鼠DRG内过表达microRNA30b/182，就可有效降低Nav1.7的过表达，有效缓解疼痛。该项目明确了microRNA30b/182的镇痛效应，为疼痛治疗提供新思路。