微小RNA-199a-5p下调后通过c-jun氨基端激酶通路促进脊髓后索损伤修复的研究

Identification of miRNomes reveals microRNA-199a-5p promoting the repairment of dosal column lesion through c-Jun N-terminal kinase pathway

目的 从微小RNA（miRNA,miR）表达谱（miRNomes）角度探讨坐骨神经预损伤促进脊髓后索损伤修复的机制.方法 39只雌性Wistar大鼠随机分为坐骨神经预损伤组、单纯脊髓后索损伤组、单纯坐骨神经损伤组和对照组.用微阵列芯片技术和生物信息学方法研究坐骨神经预损伤促进脊髓后索损伤修复的相关miRNA,并用实时定量反转录聚合酶链反应（RT-qPCR）、Western blot、免疫组织化学以及苏木素-伊红（HE）染色等技术进行生物学验证.结果 miR-199a-5p在坐骨神经预损伤组各时间窗表达下调,其靶基因促分裂原活化蛋白激酶磷酸酶2（MKP2）的蛋白表达上升,进而抑制c-Jun氨基末端激酶（JNK）的磷酸化.坐骨神经预损伤组脊髓后索损伤中心尾端脊髓神经丝蛋白明显增加且白质纤维束形态规整.单纯损伤坐骨神经并不改变miR-199a-5p和MKP2蛋白表达.结论 miR-199a-5p表达下调增加了MKP2阻断JNK磷酸化的作用,是坐骨神经预损伤促进脊髓后索损伤修复的机制之一.

Objective To explore the repair mechanism of dorsal column lesion which is promoted by sciatic nerve conditioning injury on the basis of microRNAome globally.Methods 39 female wistar rats was divided into sciatic nerve conditioning injury group,simple dorsal column lesion group,simple sciatic nerve injury group and control group randomly.Microarray and bioinformatics were used to investigate the microRNAs （miRNA,miR） which are associated with the repair mechanism of dorsal column lesion that is promoted by sciatic nerve conditioning injury.To validate the result,real-time reverse transcriptase polymerase chain reaction （RT-qPCR）,Western blotting,immunohistochemistry and hematoxylin and eosin stain were applied.Results The downregulation of miR-199a-5p in each check point of sciatic nerve conditioning injury group was significant,which induces the upregulation of mitogen-activated protein kinase phosphatase 2 （MKP2）.Thereby the upregulation of MKP2 inhibits the phosphorylation of c-Jun N-terminal kinase （JNK）.Comparing with the simple dorsal column lesion group,the expression level of neurofilament protein significantly increased and the shape of nerve fiber bundle was more regular in caudal lesion site of sciatic nerve conditioning injury group.And simple sciatic nerve injury cannot alter the expression level of miR-199a-5p and MKP2 protein.Conclusion It is one of the repair mechanisms of dorsal column lesion which is promoted by sciatic nerve conditioning injury that the downregulation of miR-199a-5p inhibits the phosphorylation of JNK by upregulating MKP2 protein.