组蛋白甲基化酶EZH2下调参与心肌细胞终末分化  

The Histone Methyltransferase EZH2 is Downregulated in the Terminal Differentiation of Cardiomyocytes

作　　者：张婉怡 张婉蕾 刘媛媛 丁玲儿 唐琦凯 李圳航 杨昊颖 李涛[1,3] ZHANG Wan-Yi;ZHANG Wan-Lei;LIU Yuan-Yuan;DING Ling-Er;TANG Qi-Kai;LI Zhen-Hang;YANG Hao-Ying;LI Tao(Department of Medical Immunology,School of Medical Technology and Translational Medicine,Hunan Normal University,Changsha 410013,China;Grade 2021 Medical Laboratory Technology Class,Health Science Center,Hunan Normal University,Changsha 410013,China;Grade 2022 Medical Laboratory Technology Class,Health Science Center,Hunan Normal University,Changsha 410013,China;Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province,Hunan Normal University School of Medicine,Changsha 410013,China)

机构地区：[1]湖南师范大学医学技术与转化学院医学免疫学教研室,长沙410013 [2]湖南师范大学医学部,长沙410013 [3]模式动物与干细胞生物学湖南重点实验室,长沙410013

出　　处：《中国生物化学与分子生物学报》2025年第3期415-425,共11页Chinese Journal of Biochemistry and Molecular Biology

基　　金：国家自然科学基金(No.81870201);湖南省自然科学基金(No.2022JJ30411);湖南省教育厅科学研究项目(No.23A0074);2024年度湖南师范大学大学生创新创业训练计划一般项目(No.2024309)资助。

摘　　要：Zeste基因增强子人类同源物2(enhancer of zeste homolog 2,EZH2)是一个组蛋白甲基转移酶,与SUZ12和EED等组成多梳抑制复合体2(polycomb repressive complex 2,PRC2),对组蛋白H3的27位赖氨酸进行三甲基化修饰,介导下游基因表观沉默。其与细胞增殖、心血管发育关系密切,但EZH2在心血管终末分化中的表达变化尚不清楚。本研究通过GEO数据库筛选胚胎及成体心肌细胞中基因的表达差异,发现EZH 2在胚胎心肌细胞高表达,在成体心肌中表达极低(P<0.0001);而PRC2成员SUZ 12和EED的表达变化不够显著。通过Tabula Muris数据库在线分析显示,成体小鼠心组织各细胞亚群在生理状态下几乎不表达EZH2。对小鼠心组织进行免疫组化染色,发现在小鼠的胚胎期和初生期心肌组织中,EZH2表达水平较高,但在出生后的第1 d表达量开始逐渐下降(P<0.0001),到第3 d几乎消失不表达。蛋白质免疫印迹结果进一步验证,发现EZH2在出生后表达迅速消失(P<0.05),EZH1可弥补EZH2下调,维持H3K27me3修饰水平。本研究进一步采用畸胎瘤干细胞P19细胞心肌诱导分化模型,发现EZH2在心肌前体细胞向自发搏动的心肌细胞分化过程中显著高表达,与心肌转录因子Gata 4表达同步(P<0.01)。通过小分子药物MS1943靶向降解EZH2,Edu掺入实验显示,其显著抑制了诱导分化中心肌细胞的增殖(P<0.01),同时RT-qPCR检测显示,增殖抑制因子CDKN1A的表达显著升高(P<0.01)。总体而言,EZH2在胚胎发育中心肌细胞中的高表达,与促进细胞增殖相关。在出生后短时间内,EZH2表达快速丧失,与心肌细胞失去增殖能力相关,是心肌终末分化的标志之一。Enhancer of zeste homolog 2(EZH2)is a histone methyltransferase It mediates trimethylation of lysine 27 on histone H3,thereby facilitating the epigenetic silencing of downstream genes.In conjunction with SUZ12,EED,and other components,it constitutes the polycomb repressive complex 2(PRC2)complex.While EZH2 is intricately involved in cellular proliferation and cardiac development,the changes in its expression during cardiac terminal differentiation remain elusive.In this study,we employed differential gene expression analysis of embryonic and adult myocardial cells using the GEO database,and found that EZH 2 is highly expressed in embryonic myocardium,but is present at very low levels in adult myocardium(P<0.0001).Conversely,the expression changes of PRC2 members SUZ 12 and EED are not as pronounced.Online analysis through the Tabula Muris database indicates that under physiological conditions,various cell subpopulations in the adult mouse heart exhibit negligible expression of EZH 2.Immunohistochemical staining of mouse cardiac tissues shows that EZH2 is highly expressed in embryonic and neonatal myocardium but declines progressively from the first day after birth(P<0.0001),becoming almost undetectable by the third day.Western blotting further confirms the rapid disappearance of EZH2 expression post-birth(P<0.05),with EZH1 compensating for the downregulation of EZH2 to maintain H3K27me3 modification levels.Additionally,using the P19 teratocarcinoma stem cell model for cardiomyocyte differentiation,it is observed that EZH2 is significantly upregulated during the transition from cardiac progenitor cells to spontaneously beating cardiomyocytes,correlating with the expression of the cardiomyocyte transcription factor Gata4(P<0.01).Targeted degradation of EZH2 using the small molecule drug MS1943 significantly inhibits the proliferation of induced cardiomyocytes,as evidenced by 5-ethynyl-2’-deoxyuridine(EdU)incorporation assays(P<0.01),and RT-qPCR reveals a marked increase in the expression of the proliferation inhi

关 键 词：Zeste基因增强子人类同源物2 心肌细胞 终末分化 细胞增殖 表观修饰 

分 类 号：Q593[生物学—生物化学]