【摘要】 不改变基因的DNA编码,通过改变DNA双链与组蛋白间紧密度来决定基因是否转录表达,这称为表观遗传编码机制。表观遗传编码的生理作用是通过组蛋白修饰和DNA甲基化,调控细胞在适当的时间、空间位置表达适当的基因,从而控制细胞的增殖状况和分化方向。在细胞发育过程中,细胞内DNA甲基化水平增龄性增高,基因转录活性逐渐降低,使细胞从幼稚增殖进入成熟分化。肿瘤细胞中出现表观遗传编码紊乱,致细胞增殖失控,不能进入分化成熟阶段。基因启动子出现甲基化重排,阻碍转录因子与启动子结合,导致基因转录丧失正常调控,合成成熟功能蛋白受阻。利用表观遗传机制(如,RNA干涉)可成为肿瘤治疗的新方法。更多还原

【Abstract】 Epigenetic code is the switch in gene expression by histone modification and DNA methylation,other than alteration in the primary nucleotide sequence of a gene.The epigenetic code is responsive to developmental,physiological,and pathological signals.And it confers cell type and temporal identities of gene expression programs.In cell developing process,with the level of DNA methylation increasing by age,the activity of gene transcription is decreasing.Distortions in DNA methylations result in cancerous cell transformation,losing the control of cell proliferation.In cancer cell,de novo methylation takes place and break down the transcription factors attach to gene promoter,transcription collapsing into disorder.The DNA methylation pattern is one of the safe cancer diagnostics at early stages of carcinogenesis.Epigenetics(such as RNA interference) can become potential method of cancer therapy.更多还原