CAJ | 학술논문

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.
목적 탐토소제량복사(LDR)대소서전혈기인조DNA갑기화적영향,이급DNMT1、MBD2재외주혈단개핵세포(PBMC)급각조직중적표체변화.방법 SP급BALB/c웅성소서30지안수궤수자표법균분위3조:대조조、단차0.5 Gy조사조화분차0.5 Gy(0.05 Gy/d ×10 d)조사조.조사조균행6MVX사선전신조사.기중분석조기효응적15지소서(5지/조)재말차조사후2h,매조10지처사,분석연지효응적령외15지소서말차조사후30 d처사.수집PBMC、신장、간장、비장、뇌급폐조직.채용정체갑기화정량시제합화고효액상색보법(HPLC)분석전혈DNA갑기화수평,RT-PCR법검측소서PBMC급각조직DNMT1화MBD2 mRNA적표체.결과 말차조사후2h,여대조조비교,분차조사조전혈DNA갑기화수평강저(량충검측방법,t=10.19화8.93,P＜0.05),DNMT1화MBD2 mRNA재소서PBMC、신장화간장중표체균강저(t=5.06、3.01、3.97、12.25、3.50화3.73,P＜0.05),MBD2 mRNA표체재비장중강저(t=3.03,P＜0.05)；이단차조사조균무명현개변.말차조사후1개월,단차、분차조사조적전혈갑기화수평교대조조차이균무통계학의의,부분차조사조소서PBMC화뇌조직MBD2 mRNA수평강저(t=3.52화2.85,P＜0.05).결론 분차LDR가인기전기인조저갑기화,저충효응구유조직특이성,가능여DNMTI、MBD2적표체강저유관.
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.