Studies On The Role Of MicroRNAs In Retinoic Acid-induced Neural Cell Differentiation

This thesis examines the effects of retinoic acid (RA) on the differentiation of neuroblastoma N2a cells. Experiments have been perfomed to analyze the role of micorRNAs (miRNAs) in the retinoic acid-induced N2a differentiation. N2a cells were treated with RA and cell differentiation was examined based on the morphology and neuronal marker. The results showed that 5 days treatment of RA induced the differentiation of N2a cells. N2a cells showed significant neuronal process extension, neurite outgrowth and cell body enlargement. Biochemical analysis showed that the expression of mature neuron maker MAP2 was significantly increased, indicating that the N2a cells were differentiated into neuron after RA treatment.A large amount dada indicates that miRNA plays important roles in the development of nervous system and neural cell differentiation. However, it is not clear whether miRNA is involved in the regulation of N2a cell differentiation. In this report, we have systematically examined the expression of miRNAs, such as miR-124, miR-125b, miR-9 and let-7a, in N2a cells after RA treatment. The results showed that miR-124 was up-regulated, miR-125b was down-regulated, while let-7a had no change.Furthermore, we have examined the involvement of three different miRNAs in the regulation of N2a cell differentiation. Overexpression of miR-124 in N2a cells resulted in the induction of N2a cell differentiation, while inhibition of miR-124 blocked the effects. In addition, overexpression of miR-124 in N2a cells induced the expression of MAP2 protein, indicating that miR-124 participates in the regulation of N2a cell differentiation. On the other hand, overexpression of miR-125 and miR-9 had no effects on the N2a cell differentiation.