Low-methylation Status Of Estrogen Receptor α Gene Promoter In Pristane-induced ApoE^-/- C57BL/6Mouse-a Model Of Lupus With Atherosclerosis

【Objective】Analysing the whole genomic DNA methylation level and estrogenreceptorα(ERα)gene promoter methylation status in systemic lupuserythematosus (SLE) with atherosclerosis (AS) model mouse, to explore itsrole in pathogenesis of SLE with AS.【Methods】11apoE-/-C57BL/6mice were randomly divided into model group (groupA) and control group (group B);11ordinary C57BL/6mice were also randomlydivided into model group (group C) and control group (group D).Singleintraperitoneal injection of pristane0.5ml for model group, singleintraperitoneal injection of normal saline0.5ml for control group;8months after injection,all mice were bled to death,genomic DNA wasextracted from spleen,detecting the total genomic DNA methylationlevel,and pyrosequencing was performed to determine the methylationstatus of ER α gene promoter,comparing the differences betweengroups.ANOVA,LSD-t test,Tamhane’s T2test were used for statisticalanalysis with software SPSS17.0.【Results】1.Analysis of the whole genomic DNA methylation levelThe total genomic DNA methylation were（4.7±1.5）%、（5.1±0.5）%、（6.6±1.6）%、（7.5±1.6）%in group A,group B,group C,group D.The totalgenomic DNA methylation level in group A and C were significantly lowerthan that in group D (P＜0.05).Compared with group B, the total genomicDNA methylation levels in group A was significantly decreased (P＜ 0.05).The difference between group B and group D was not statisticallysignificant (P＞0.05）.2.The methylation status of estrogen receptorα(ERα) gene promoter2.1The average methylation index of estrogen receptor alpha genepromoterThe average methylation index of ERαgene promoter were (13.0±3.1）%、（26.7±7.2）%、（15.7±3.8）%、（21.4±4.2）%in group A,group B,groupC,group D.The average methylation index of ERαgene promoter in group Aand C were significantly lower than that in group D (P＜0.05).Comparedwith group B, the average methylation index of ERαgene promoter in groupA were significantly decreased (P＜0.05).While compared with group D, theaverage methylation index of ERαgene promoter in group B was increased,but the difference was not statistically significant (P＞0.05）.2.2The methylation index of each CpG loci in ERα gene promoterregionCompared with group D,the methylation index of all of the7CpG lociin ERαgene promoter region in group C and group A were decreased, andeach group had a statistically significant difference of3CpG loci (P＜0.05); The methylation index of all of the7CpG loci in group B wereincreased, of which there are4CpG loci has statistical significancedifference(P＜0.05).Compared with group B, the methylation index of allof the7CpG loci in group A were significantly decreased (P＜0.05).【Conclusion】The total genomic DNA methylation in pristane-induced apoE-/-C57BL/6lupus with atherosclerosis mouse model is decreased,and the ERαgenepromoter are in low-methylation status, epigenetics may play an importantrole in the pathogenesis of SLE with AS.