实验性2型糖尿病小鼠肝脏组蛋白H3表观修饰的变化及其意义

Changes and significance of hepatic histone H3 epigenetic modification in type 2 diabetic mice

目的:研究肝脏组蛋白H3表观修饰的变化在2型糖尿病小鼠发病过程中的作用,探讨其临床意义。方法:30只C57BL/6J小鼠分为正常组、高脂高糖组和糖尿病组,正常组和高脂高糖组小鼠分别给予正常饲料和高脂高糖饲料,糖尿病模型采用高脂高糖饲料联合注射链脲佐菌素(STZ)方法构建。采用HE染色、免疫印迹法、实时定量PCR和ChIP技术分别检测小鼠肝脏病理学变化、肝脏中总组蛋白H3的修饰状况及与糖代谢相关基因丙酮酸激酶(Pklr)、葡萄糖转运蛋白2(Glut2)、葡糖糖激酶(Gck)、过氧化物酶体增生物激活受体γ辅助活化因子1(Ppargc1a)和胰岛素受体(Insr)的表达水平和基因启动子区组蛋白的修饰变化。结果:糖尿病组小鼠肝脏病理学(HE染色)和组蛋白修饰模式均发生了明显变化。与正常组比较,高脂高糖组小鼠H3K23的乙酰化下降(P<0.01),H3K9Ac和H3K9Me2修饰水平上调(P<0.01),H3K4Me保持不变(P>0.05),糖代谢相关基因Pklr、Glut2和Gck的表达水平升高(P<0.01);糖尿病组小鼠H3K23Ac和H3K9Ac修饰水平下降(P<0.05或P<0.01),H3K9Me2和H3K4Me的修饰水平升高(P<0.01),糖代谢相关基因Pklr、Glut2、Gck、Ppargc1a和Insr表达水平明显下调(P<0.05或P<0.01)。Pklr、Glut2启动子区H3K23Ac、H3K9Ac、H3K9Me2和H3K4Me修饰水平变化与基因的表达水平变化相吻合。结论:肝脏组蛋白表观修饰变化可能参与了2型糖尿病的发生发展。

Objective To study the role of liver total histone epigenetic modification changes in the development of type 2diabetes mellitus in the mice,and to explore its clinical significance.Methods Thirty C57BL/6Jmice were divided into normal group,high-fat high-sucrose（HFS）group and type 2diabetes mellitus（T2DM）group.The mice in normal and HFS groups were given regular diet and HFS diet,respectively,while type 2diabetic mice were induced by HFS diet plus streptozotocin（STZ）.HE staining,Western blotting,Quantitative PCR and ChIP assay were used to analyze the pathological changes of liver tissue of the mice,total histone H3 modification,the expression levels of glucose metabolism-related genes and histone H3 modification in gene promoter.Results The liver pathology after HE staining and modification patterns of histone of the mice in T2 DM group were significantly different from other groups.Compared with normal group,the H3K23 acetylation of the mice in HFS group was decreased（P〈0.01）,the modification levels of H3K9 Ac and H3K9Me2 were increased（P〈0.01）,the level of H3K4 Me had no change（P〉0.05）,and the expression levels of glucose metabolism-related genes Pklr,Glut2 and Gck were increased（P〈0.01）.Compared with normal group,the modification levels of H3K23Ac（P〈0.01）and H3K9Ac（P〈0.05）in T2 DM group were decreased,the modification levels of H3K9Me2 and H3K4Me were increased（P〈0.01）,and the expression levels of glucose metabolism-related genes Pklr,Glut2,Gck,Ppargc1 a and Insr were decreased（P〈0.05 or P〈0.01）.Moreover,the changes of H3K23 Ac,H3K9Ac,H3K9Me2 and H3K4Me modification in gene promoter of Glut2 and Pklr showed consistent with its expression levels.Conclusion The epigenetic modification changes of liver histone might participate in the occurrence and development of type 2diabetes mellitus.