Deregulation of miRNA-181c potentially contributes to the pathogenesis of AD by targeting collapsin response mediator protein 2 in mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is usually accompanied by abnormal gene expression. The 20 to 25 nucleotide (nt) tiny regulators, known as micro ribonucleic acids (miRNAs), have been found to play important roles in the etiology and pathogenesis of various biological processes. The purpose of the current study was to identify the aberrant expression of microRNAs in the hippocampus of an AD mouse model and to investigate its potential role during the progression of AD. The results from microarray analysis showed that several miRNAs were deregulated in the hippocampus tissue of SAMP8 mice compared to SAMR1 mice. Among the deregulated miRNAs, a significant decrease in miR-181c was validated by quantitative real-time PCR. Bioinformatic analysis revealed that miR-181c might be involved in the regulation of axon guidance, MAPK signaling, dorso-ventral axis formation and long-term depression. Moreover, the results of a luciferase activity assay, western blot analysis and immunofluorescent staining showed that over-expression of miR-181c targets the 3′-untranslated region (3′-UTR) of collapsin response mediator protein 2 (crmp2) through its binding sites and down-regulates crmp2 protein abundance at the post-transcriptional level. Taken together, these findings suggested that crmp2 is a target of miR-181c and that the abnormally low expression of miR-181c in the hippocampus of SAMP8 mice could lead to an increase of the crmp2 protein level in AD mice, which might potentially play a role in the pathogenesis of Alzheimer's disease.