Differential expression of miR-34a, miR-141, and miR-9 in MPP+-treated differentiated PC12 cells as a model of Parkinson's disease.

Parkinson's disease (PD) is a debilitating neurodegenerative condition characterized by the loss of dopaminergic neurons in substantia nigra. MPP+ as a dopaminergic neurotoxin induces many parkinsonian-like symptoms in cell culture. MicroRNAs are noncoding RNAs which their deregulation participates in neurodegeneration by affecting most of the mechanisms responsible for neurodegenerative diseases. Differentiated PC12 cells impaired by MPP+ were served as an in vitro model of PD. The aim of present research is to evaluate expression of several miRNAs and possible target genes in MPP+-treated differentiated PC12 cells. PC12 cells were differentiated by induction of NGF. Neurite outgrowth was quantified using image analysis software. MTS assay was served to assess cell viability. DCFH-DA assay and Annexin v staining were used to detect reactive oxygen species (ROS) levels and apoptosis, respectively. An in-silico study was performed to make interaction analysis between selected mRNAs and microRNAs. The expression levels of microRNAs and target genes were examined by RT-qPCR. NGF induced differentiation led to a substantial increase in neurite lengths means and percentage of the neurite-bearing cells. NGF-differentiated PC12 cells substantially expressed TH and retained their dopaminergic characteristic after differentiation. NGF treatment enhanced TH gene expression. MPP+ exposure caused loss of cell viability and induced apoptosis and ROS overproduction. SIRT1, BCL2, and BDNF were down-regulated after MPP+-treatment. In contrast, MPP+ toxicity significantly caused up-regulation in miR-34a, miR-141, and miR-9. The present study showed altered levels of selected microRNAs in response to MPP+ for the first time, suggesting that perturbed expression of them may contribute to the PD-related pathogenic processes, probably by affecting the expression of BCL2, BDNF, and SIRT1 as potential targets.