MicroRNA-124 Enhances Dopamine Receptor Expression and Neuronal Proliferation in Mouse Models of Parkinson's Disease via the Hedgehog Signaling Pathway by Targeting EDN2.

Recent studies have elaborated on the concept that a number of microRNAs (miRNAs) have a potential effect on the pathogenesis and development of Parkinson's disease (PD). PD is recognized as a common progressive bradykinetic disorder that results from the death of dopaminergic neurons in the substantia nigra. The purpose of this study was to explore whether microRNA-124 (miR-124) affected dopamine receptor (DAR) expression and neuronal proliferation and apoptosis in the 1-methyl-4-pheny-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse models of PD. The targeting relationship of miR-124 and EDN2 was confirmed through bioinformatic predictions and dual-luciferase reporter assay. The expression of miR-124 and EDN2 was altered to assess their effect on the expression of DAR in the substantia nigra and isolated neurons, as well as the neuronal proliferation and apoptosis rate. The obtained results implied that the treatments of miR-124 mimic and si-EDN2 resulted in elevated expressions of Glil, SHH, PTCH1, DAT, DRD1, and DRD2. However, these treatments facilitated neuronal proliferation and suppressed neuronal apoptosis, corresponding to reduced expression of caspase-3 and Bax, as well as increased levels of Bcl-2 expression. These results were discovered to be achieved through the activation of the Hedgehog signaling pathway. With this taken into account, our study demonstrated that miR-124 overexpression promoted DAR expression and neuronal proliferation and suppressed neuronal apoptosis by downregulating EDN2 via activating the Hedgehog signaling pathway.