MicroRNAs 144, 145, and 214 are down-regulated in primary neurons responding to sciatic nerve transection

MicroRNAs (miRNAs) play an important role in the development, differentiation, proliferation, survival, and oncogenesis of cells and organisms including nervous system. However, the role of miRNAs in primary neurons of dorsal root ganglion (DRG) after injury was not clear. In this study, a miRNA microarray analysis was performed, and a total of 21 miRNAs were found to be down-regulated following unilateral sciatic nerve transection. The miR-144, miR-145, and miR-214 were further validated using quantitative reverse transcriptase PCR (qRT-PCR). Moreover, in situ hybridization (ISH) experiments using locked nucleic acid (LNA)-modified DNA oligonucleotide probes verified that miR-144, miR-145, and miR-214 were expressed in primary neurons of DRG and down-regulated following sciatic nerve transection. Predictions of potential miRNA targets involved were identified by performing a bioinformatics analysis. These predictions were tested using miRNA luciferase reporter vectors, with Robo2 and srGAP2 evaluated as the potential targets of miR-145 and miR-214, respectively. The role of miR-145 in cultured primary neurons was also investigated, and the result found that miR-145 miR-145 inhibited neurite growth and down-regulated Robo2 expression. Finding from this study suggested that miRNAs of DRG can mediated the course of regeneration including through Slit-Robo-srGAP signaling pathway after injury.