小剂量辐射对小鼠全基因组DNA甲基化的影响  

Genome-wide DNA methylation changes induced by low dose radiation in mouse

作　　者：王静子[1] 张有为[1] 冒晓蓓[1] 刘小北[1] 任丽丽[1] 褚晓源[1] 

机构地区：[1]南方医科大学南京临床学院南京军区南京总医院肿瘤内科,210002

出　　处：《中华放射医学与防护杂志》2013年第4期341-345,共5页Chinese Journal of Radiological Medicine and Protection

基　　金：南京军区医药卫生科研基金课题（No.11MA092）

摘　　要：目的 探讨小剂量辐射（LDR）对小鼠全血基因组DNA甲基化的影响,以及DNMT1、MBD2在外周血单个核细胞（PBMC）及各组织中的表达变化.方法 SP级BALB/c雄性小鼠30只按随机数字表法均分为3组：对照组、单次0.5 Gy照射组和分次0.5 Gy（0.05 Gy/d ×10 d）照射组.照射组均行6MVX射线全身照射.其中分析早期效应的15只小鼠（5只/组）在末次照射后2h,每组10只处死,分析延迟效应的另外15只小鼠末次照射后30 d处死.收集PBMC、肾脏、肝脏、脾脏、脑及肺组织.采用整体甲基化定量试剂盒和高效液相色谱法（HPLC）分析全血DNA甲基化水平,RT-PCR法检测小鼠PBMC及各组织DNMT1和MBD2 mRNA的表达.结果 末次照射后2h,与对照组比较,分次照射组全血DNA甲基化水平降低（两种检测方法,t=10.19和8.93,P＜0.05）,DNMT1和MBD2 mRNA在小鼠PBMC、肾脏和肝脏中表达均降低（t=5.06、3.01、3.97、12.25、3.50和3.73,P＜0.05）,MBD2 mRNA表达在脾脏中降低（t=3.03,P＜0.05）；而单次照射组均无明显改变.末次照射后1个月,单次、分次照射组的全血甲基化水平较对照组差异均无统计学意义,仅分次照射组小鼠PBMC和脑组织MBD2 mRNA水平降低（t=3.52和2.85,P＜0.05）.结论 分次LDR可引起全基因组低甲基化,这种效应具有组织特异性,可能与DNMTI、MBD2的表达降低有关.Objective To study the whole genome DNA methylation changes induced by low dose radiation （LDR） in mouse,and mRNA expression profiles of DNMT1 and MBD2 in peripheral blood mononuclear cell （PBMC） and tissues.Methods Thirty male BALB/c mice were randomly divided into 3 groups：control,single exposure （0.5 Gy）,and fractionated exposure of 6 MV X-rays for 10 d （0.05 Gy/d × 10 d）.Control mice were sham-treated.To determine the immediate （early） effect of irradiation,15 mice （5/group） were sacrificed 2 h after the last irradiation.The other 15 mice were sacrificed 1 month after the last irradiation （delayed effect）.Before sacrifice,blood was sampled immediately.Kidney,liver,spleen,brain and lung tissues were collected.A global DNA methylation quantification Kit and highperformance liquid chromatography （HPLC） were used to investigate the methylation level in blood DNA.The expressions of DNMT1 and MBD2 were determined by RT-PCR.Results For the early effects of irradiation,as compared with controls,fractionated exposure to X-ray irradiation led to the significant depression of global DNA methylation level in blood （t =10.19 and 8.93,P 〈 0.05）.DNMT1 and MBD2 mRNA were down-regulated in PBMC,kidney and liver （t =5.06,3.01,3.97,12.25,3.50 and 3.73,P 〈0.05）,and MBD2 was also down-regulated in spleen （t =3.03,P 〈 0.05）.However,no changes were observed in single exposed group.As for the delayed effects,the methylation levels of blood were not changed in the single or fractionated exposed groups,and only MBD2 mRNA was down-regulated in PBMC and brain of fractionated exposed group （t =3.52 and 2.85,P 〈 0.05）.Conclusions Fractionated LDR exposure can induce genome DNA hypomethylation,which is tissue-specific,and may be related with down-regulation of DNMT1 and MBD2.

关 键 词：小剂量辐射 甲基化 甲基转移酶 甲基化结合蛋白 

分 类 号：R[医药卫生]