Line-1 Expression And Retrotransposition Of 293T Cells Induced By PCB153

Objective:Polychlorinated biphenyls(PCBs)is a kind of durable,bioaccumulative,highly toxic organic pollutants.2,2',4,4',5,5'-hexachlorobiphenyl(PCB153)is one of the most abundant PCBs congeners in human tissues and is closely related to human health.PCB153 can lead to DNA damage and genome instability.The long interspersed element-1(LINE-1)is the unique retrotransposon in the human genome which can be independently transposed,transpositions of LINE-1 could reduce the stability of the genome.This study intends to analyze the expression and transposition of LINE-1,cell apoptosis and DNA damage in the human renal epithelial cells(293T cells)exposed by PCB153 to provide new insights for the molecular toxicity of PCBs.Methods:(1)Flow cytometry was used to detect the apoptosis of 293 T cells.(2)Fluorescence quantitative PCR(real-time PCR)was used to detect the m RNA expression of LINE-1.LINE-1 protein expression level was detected by Western blot.(3)Real-time PCR was used to detect the copy number of LINE-1 in genome.(4)Pyrosequencing was used to detect the methylation status of LINE-1.m RNA expression of DNA methylation related genes were measured by Real-time PCR.(5)Immunofluorescence was used to detect DNA damage in 293 T cells.m RNA expression of DNA damage repair related genes were measured by real-time PCR.Results:(1)293T cells apoptosis rate was increased exposed to 15?mol/L PCB153 compared with the control group.(2)Compared with the control group,the expression of LINE-1 m RNA and protein in 293 T cells was gradually increased after 48 h treated with different concentrations of PCB153(5?mol/L,10?mol/L,15?mol/L),and the difference was most obvious at96 h in the expression of LINE-1 protein.(3)Exposed to different concentrations of PCB153 caused a significant increment of LINE-1 copy number in 293 T cells after 96 h.The difference was most obvious in15?mol/L PCB153 exposed group.(4)Exposed to 15?mol/L PCB153 led to a decrease in LINE-1 methylation in 293 T cells at 96 h.Meanwhile,the expression of methylase DNMT3 B m RNA in 293 T cells was decreased and the expression of demethylase TET1 m RNA was increased.(5)Compared with the control group,15?mol/L PCB153 could cause DNA damage in the cells at 96 h.Compared with the control group at 96 h,the expression of RAD51 D and XRCC2 m RNA in 293 T cells was decreased,and the expression of XRCC5 and XRCC6 m RNA was increased.Conclusions:(1)PCB153 exposure can cause cell apoptosis.(2)PCB153 exposure can reduce LINE-1 methylation,increase LINE-1 expression,and may induce LINE-1 transposition.(3)PCB153 exposure can cause DNA damage and have an effect on DNA damage repair.