miR-124-3p attenuates MPP⁺-induced neuronal injury by targeting STAT3 in SH-SY5Y cells

Ample evidence has demonstrated the involvement of microRNAs in Parkinson's disease pathogenesis. miR-124-3p was reported to be able to improve neural functional recovery. However, the underlying mechanism of miR-124-3p in Parkinson's disease progression was not well established. This study was designed to investigate the role of miR-124-3p in methyl phenyl pyridinium iodide (MPP)⁺-induced SH-SY5Y cells, an in vitro Parkinson's disease model. It is observed that miR-124-3p expression was decreased, and STAT3 expression was increased in MPP⁺-induced SH-SY5Y cells. miR-124-3p overexpression attenuated MPP⁺-induced neuronal injury, displayed as increased cell viability and superoxide dismutase activities, as well as reduced cell apoptosis, Caspase-3 activity, lactate dehydrogenase activity, inflammatory factors TNF-α, and IL-1β levels and reactive oxygen species generation. Moreover, STAT3 was confirmed to be a miR-124-3p target. Restored STAT3 expression reversed miR-124-3p-induced neuroprotective effects against MPP⁺-mediated neuronal injury. These data demonstrated that miR-124-3p contributed to neuroprotective effects in MPP⁺-induced Parkinson's disease cell model by targeting STAT3. Impact statement PD affects millions of people in the world, causing uncontrolled tremors. MicroRNAs, a class of endogenous single-stranded non-coding transcript with approximately 22 nucleotides, could bind to the 3″ UTR of their targets. The functional action of miR-124-3p in PD was not fully elucidated. Our study found that ectopic expression miR-124-3p attenuated MPP⁺-induced injury in PD model in vitro by suppressing neurotoxicity, neuronal apoptosis, neuroinflammation, and oxidative stress. Moreover, we validated that miR-124-3p could bind to STAT3 mediating the neuroprotective effect of miR-124-3p. We believe this study will be interesting for readers of this area.