After sciatic nerve conditioning injury miR-124-3p regulates GAP-43 expression in dorsal root ganglion neurons and further promoting neurite growth via STAT3

Abstract

Objective To study the effect of sciatic nerve conditioning injury on repairment of dorsal column lesion via investigating the alteration of miRNomes. Methods To study the microRNAs which are associated with dorsal column lesion whose repairment is promoted by sciatic nerve conditioning injury, the microRNA profiles of dorsal root ganglion in sciatic nerve conditioning injury group and simple dorsal column lesion group were investigated by Microarray and bioinformatics. And then RT-qPCR, western blot, immunofluorescence staining and antisense oligonucleotide (AMO-124) were applied to validate the result of microarray. Results miR-124-3p was significantly upregulated on 7 d and 14 d post dorsal column lesion in simple dorsal column lesion group, whereas it was downregulated on 7 d and 14 d post dorsal column lesion in sciatic nerve conditioning injury. Compared with normal dorsal root ganglion (DRG) neurons, expression was increased and neurite was prolonged in miR-124-3p inhibited neurons. Compared with control group, there was no statistical difference about the expression of signal transducer and activator of transcription 3 (STAT3) mRNA among each check point of every group. On 7 d and 14 d post dorsal column lesion, STAT3 protein expression was significantly upregulated in sciatic nerve conditioning injury group, whereas it was significantly downregulated in simple dorsal column lesion group. Compared with normal DRG neurons, immunofluorescence of STAT3 was enhanced, neurite was prolonged and the expression of p-STAT3 protein and protein was upregulated in miR-124-3p inhibited neurons. Compared with normal DRG neurons, in AG490+AMO-124 co-inhibited neurons, the length of neurite and the expression of p-STAT3 protein and protein have no statistical difference whereas the expression of STAT3 was significantly upregulated. Conclusion It is one of the mechanisms of sciatic nerve conditioning injury promoting dorsal column lesion that the downregulation of miR-124-3p in DRG neurons increases the expression of GAP-43 protein via upregulating STAT3 protein. Key words: Sciatic nerve; Wounds and injuries; MicroRNAs; Axons