Study On The Histone Mechanism Of Food-Derived Pb Exposure To Dendritic Spine

Food metal pollution is a worldwide safety problem.The effects of Pb on children’s health is a hot spot in the field of toxicology.Food is an important source of Pb poisoning in human body.Pb exposure seriously damaged the central nervous system,reproductive system,cell growth and development.The molecular mechanism of low-dose Pb exposure to the dendritic injury has been studied,but the study on the epigenetic mechanism of Pb exposure to the hippocampus of the brain is unclear.Therefore,the purpose of this paper is to discover the effect of Pb exposure on histone in hippocampal neurons and its molecular mechanism.It may provide a reliable basis for the treatment of pb-injuryed disease.Objective To investigate the effect of Pb exposure on the H3K27me3 of hippocampal neurons in rats and whether changethe regulation of dendritic related gene;The role of EZH2 in neuronal development and the formation of spine;To explore the effect of Pb exposure on histone methylation EZH2;To study the relationship betweem mi R-137 and EZH2 after Pb exposure.Methods 1.The effect of food Pb exposure on the expression of groups of neurons protein in hippocampus was studied in vitro.The exposure dose of cultured hippocampal neurons was 5 μM and the exposure time was DIV3-14.The protein expression was detected by western blot,and the expression of gene was detected by the immune technique and Q-PCR.2.The expression of EZH2 in the development neuron was conductedin vivo and vitro.3.The effect of Pb exposure on the expression of EZH2 was studied in vivo and in vitro.For in vivo experiment,the dose of Pb was 250 ppm.4.The regulation of mi R-137 on EZH2 after Pb exposure was studied in vitro.The expression of related genes was detected by Q-PCR.Results1.During the development of hippocampal neurons,the expression of EZH2 decreased significantly(P<0.001).2.Pb exposure significantly reduced the expression of EZH2 in the hippocampus of neonatal rats,however,it is no significant effect on the cortical.3.Luciferase reporter assay showed that the interaction between mi R-137 and EZH2 was up-regulated,and the expression of mi R-137 was increased by lead exposure(P<0.05).4.H3K27me3 protein expression level was significantly decreased after Pb exposure(P<0.001),which is not affected by the near site of H3K27me3S28P;further study found that Pb can inhibite the expression of H3K27me3 by down-regulate of EZH2 expression.5.H3K27me3 changed the level of genes involved in the formation of dendritic spines after Pb exposure.Conclusions 1.The expression of EZH2 decreased gradually with the development of mature neurons,and the inhibition of EZH2 expression induced by lead exposure could damage the formation of dendritic spines.2.Through EZH2 and mi R-137 negative feedback amplification effect lead to histone methylation down regulated after Pb exposure.