Regulatory mechanism of miR‐20a‐5p in neuronal damage and inflammation in lipopolysaccharide‐induced BV2 cells and MPTP‐HCl‐induced Parkinson's disease mice

Abstract

AbstractBackgroundParkinson's disease (PD) is a prevailing neurodegenerative disorder increasingly affecting the elderly population. The involvement of microRNAs (miRNAs) in PD has been confirmed. We sought to explore the molecular mechanism of miR‐20a‐5p in PD.MethodsLipopolysaccharide (LPS)‐induced BV2 cell model and 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine hydrochloride (MPTP‐HCl)‐induced PD mouse model were established. miR‐20a‐5p, inducible nitric oxide synthase (iNOS), interleukin (IL)‐6, tumour necrosis factor (TNF)‐α, transforming growth factor (TGF)‐β1, and IL‐10 expression in BV2 cells was examined by reverse transcription – quantitative polymerase chain reaction. Cell viability was assessed by MTT assay. The apoptotic rate and levels of Bcl‐2, Bax, cleaved caspase‐3, and signal transducer and activator of transmission (STAT)3 were examined by flow cytometry and Western blot. Bioinformatics software predicted the potential binding sites of miR‐20a‐5p and STAT3. Dual‐luciferase experiment verified the binding relationship. Iba1‐positive and tyrosine hydroxylase (TH)‐positive cell numbers in substantia nigra pars compacta were detected by immunohistochemistry. The effect of miR‐20a‐5p on motor function in MPTP‐induced PD mice was detected by Rota‐rod test, Pole test, Traction test and Beam‐crossing task.ResultsmiR‐20a‐5p was under‐expressed in LPS‐induced BV2 cells. Overexpression of miR‐20a‐5p increased the viability of LPS‐induced BV2 cells and reduced apoptosis rates. Moreover, overexpression of miR‐20a‐5p reduced cleaved caspase‐3, Bax, iNOS, IL‐6, and TNF‐α and increased Bcl‐2 and TGF‐β1, and IL‐10. miR‐20a‐5p targeted STAT3. STAT3 overexpression partially reversed miR‐20a‐5p overexpression‐mediated effects on LPS‐induced BV2 cell viability, apoptosis, and inflammatory responses. miR‐20a‐5p overexpression inhibited MPTP‐induced STAT3 and α‐synuclein levels, microglia activation, and inflammatory response, and reduced the loss of TH‐positive cells in mice. miR‐20a‐5p overexpression ameliorated MPTP‐induced dyskinesia in PD model mice.ConclusionmiR‐20a‐5p alleviates neuronal damage and suppresses inflammation by targeting STAT3 in PD.