Study On The Regulation Of BER Pathway By BRCA1 During DNA Oxidative Damagein SH-SY5Y Cells Induced By Aluminum

Objective:Aluminum（Al）is an important environmental pathogenic factor for neurodegenerative diseases.There is already evidence that aluminum can cause oxidative damage to the central nervous system,and BRCA1 may play an important regulatory role in it.This study mainly examined the possible role of BRCA1regulating the BER pathway in aluminum-induced SH-SY5Y cell DNA oxidative damage,and provided important experimental data and clues for further exploring the neurotoxic mechanism of aluminum.Methods:NSE immunofluorescence method was used to identify the neuron characteristics of SH-SH5Y cells;MTS method was used to detect cell activity to determine the dose and time of AlCl₃ neurotoxic cell model;after 24 hours of culture,the SH-SY5Y cell morphology was observed with an inverted microscope;2’,7’-dihydrodichlorofluorescent yellow sodium diacetate（DCFH-DA）fluorescence staining flow cytometry was used to determine intracellular ROS content;WST-1method was used to measure SOD（superoxide dismutase）activity;MitoSOX?Red method to measure ROS level in mitochondria;ATP content,total cell and 8-OHdG content in mitochondria with ELISA kit;detection of nDNA damage with comet assay;BRCA1,OGG1,APE1 mRNA measurement with Real-time PCR Expression levels;BRCA1,OGG1,and APE1 protein expression levels were measured by Western blot;the effects of aluminum chloride on the levels of OGG1 in mitochondria and the co-localized expression of OGG1 and BRCA1 were measured by immunofluorescence.Results:1.As the dose of AlCl₃ increased,the activity of SH-SY5Y cells gradually decreased.2.Active oxygen level and mitochondrial lipid peroxidation level increased significantly,and antioxidant enzyme SOD decreased significantly.3.The intracellular ATP content decreased,the total 8-OHdG level and mitochondrial8-OHdG level increased significantly,and the phenomenon of nDNA tailing in the comet experiment also increased significantly.5.The transcription and protein expression levels of BRCA1,OGG1 and APE1 key BER genes decreased,mitochondrial OGG1 protein levels decreased,and co-localization of OGG1 and BRCA1 decreased.5.After quercetin pretreatment,the above injuries were reduced.Conclusion:1.Aluminum exposure may induce a decrease in cell survival rate by disrupting the oxidative-antioxidant balance in cells and mitochondria,aggravating oxidative damage to nDNA and mtDNA.2.Aluminum exposure can downregulate BRCA1 and BER,reduce the level of OGG1 in mitochondria,and weaken the interaction between BRCA1 and OGG1.3.After quercetin pretreatment,it has a protective effect on the above process.It is suggested that the down-regulation of BRCA1 and BER pathways plays an important role in DNA oxidative damage caused by aluminum exposure.