Effects Of MiR-181b On Autophagy In Alzheimer’s Disease Cell Model

Objective: Autophagy is a conserved metabolic process that occurs extensively in eukaryotic cells.It is a lysosomal-dependent degradation pathway in which cell lysosomes degrade their organelles and other macromolecular substances.In recent years,many studies have shown that abnormalities of autophagy can lead to the accumulation of denatured proteins and damaged organelles,which may be an important cause of neurodegenerative diseases such as Alzheimer’s disease.The regulatory mechanism of autophagy is very complex and involves many signaling pathways.Micro RNA plays a regulatory role in autophagy by regulating the expression of autophagy-related genes.In recent years,many studies have shown that miRNAs are closely related to the occurrence and development of AD.Among them,miR-181 b is very abundant in normal human cerebrospinal fluid and serum and is significantly decreased in AD patients.It has been demonstrated that miR-181 b promotes neurite outgrowth and inhibits and delays the deformity of axons.These studies indicate that there is a correlation between miR-181 and nervous system diseases such as AD,and miR-181 b has little information on the regulation of autophagy in AD cell model and its mechanism of action.On this basis,we constructed AD cell model to explore the impact of miR-181 b on AD cell autophagy and its mechanism of action,which may provide new targets and directions for the prevention and treatment of AD.Methods: In this study,PC12 cells(rat chromaffin neuroma cells)and neurotoxin Aβ25-35 AD cell model was prepared,the activity of PC12 cells was detected by MTT assay,and Aβ25-35 treated cells treated with transmission electron microscopy The number of autophagosomes was observed.The expression of autophagy-related protein LC3-II protein and the expression of P70S6 K,AKT and phosphorylated protein were detected by Western blot.The expression of miR-181 b was determined by real-time fluorescence quantitative PCR,and the effect of miR-181 b on m TOR pathway and autophagy was further observed by transfecting miR-181 b mimic / inhibitor.Results: The results of this experiment show that in Aβ25-35-treated PC12 cells,cell viability decreased.At the same time,the expression of autophagy-related protein LC3-Ⅱ was up-regulated.The number of autophagosomes was increased and the expression of miR-181 b was down-regulated under transmission electron microscope.Transfection of miR-181 b with mimic up-regulates miR-181 b can protect PC12 cells from Aβ25-35-induced cytotoxicity,increase cell viability,and inhibit Aβ25-35-induced PC12 cell autophagy.Compared with Aβ25-35 group,the levels of p-AKT,p-m TOR and p-P70s6 k were significantly increased after miR-181 b was up-regulated,while the results were the opposite after transfection with miR-181 b inhibitor.Conclusions: Aβ25-35 induces autophagy in PC12 cells and down-regulates miR-181 b expression in AD cell models.Overexpression of miR-181 b in Aβ25-35-treated PC12 cells inhibited autophagy.Mi R-181 b may be involved in Aβ25-35-induced autophagy regulation in a m TOR-dependent manner.