Department of Medical GeneticsDepartment of Medical Genetics表观遗传学染色质结构的分子水平研究00Department of Medical GeneticsDepartment of Medical GeneticsAny question? Contact me at: BBS:楚布衣 (丁香园) Email: (Google talk) QQ：2308659 Tel:757475Department of Medical GeneticsDepartment of Medical GeneticsDepartment of Medical Genetics多色FISH （2424种染色）种染色）染色体病？ 染色体结构？Department of Medical GeneticsDepartment of Medical GeneticsDepartment of Medical Genetics T(9:22)相互易位导致慢性粒细胞白血病Department of Medical GeneticsDepartment of Medical GeneticsDepartment of Medical GeneticsDepartment of Medical GeneticsDepartment of Medical GeneticsDepartment of Medical GeneticsWhat is epigenetics： the Different phenotype caused by different genome decoding in different environments.How is epigenetics: environment is the key. chromatin is the most important environment of DNADepartment of Medical GeneticsDepartment of Medical Genetics表观遗传DNA甲基化组蛋白修饰和组蛋白密码染色质重塑非编码RNA调控Department of Medical GeneticsDepartment of Medical GeneticsThe roles of chromatin structure in epigenetics and transcription Epigeneticschromatin TranscriptionHistone variantsChromatin remodelingNon-coding RNA DNA methylationHistonemodificationsChromatin trans-actingfactorsRoeder, 2010Department of Medical GeneticsDepartment of Medical GeneticsThe molecular mechanism of epigeneticsChromatin: an epigenetic platformEpigenetic mechanisms: . DNA methylation . Histone modifications . Chromatin remodeling . Histone variants . RNAi . DNA/RNA editingAllis, Jenuwein and Reinberg, Epigenetics 2006储存信息组织信息表达信息Department of Medical GeneticsDepartment of Medical Genetics先有细胞，还是先有DNA？ 谁因谁果？自然环境和人相互影响；基因组环境与基因组也是相互影响的。道法自然，天人合一。基因组DNA和其所处环境的鸡和蛋问题：Department of Medical GeneticsDepartment of Medical Genetics“the causal interactions between genes and their products, which bring the phenotype into being”Conrad Hal Waddington (19051975)Conrad Hal Waddington: the last Renaissance biologist?Nature Reviews Genetics 3, 889-895,2002Epigenetics基因的产物形成环境来影响基因！Department of Medical GeneticsDepartment of Medical Genetics哈佛大学遗传学教授乔治切奇代孕母亲的不同，对后代的影响？Department of Medical GeneticsDepartment of Medical Genetics一、染色质结构与核小体二、染色质重塑三、方法与应用Department of Medical GeneticsDepartment of Medical Genetics不同生物的遗传信息（基因）表达特点 病毒：时间依赖性调节和利用宿主细胞的机制； 细菌：组成性表达+负反馈调控； 真核生物：以核小体为基本单位的染色质，以激活和沉默为基本方式调控基因的表达。Department of Medical GeneticsDepartment of Medical Genetics DNA序列缠绕在核心组蛋白的八聚体上DNA所处环境：核小体Department of Medical GeneticsDepartment of Medical Genetics染色质: 阴阳理论常染色质异染色质- 较为疏松- 基因密度高- 基因活化- 在S早期复制- DNA缺甲基化- 组蛋白H1缺乏- 组蛋白具有活化性质的修饰- 高度致密- 基因密度低- 基因沉默- 在S后期复制- DNA过甲基化- 组蛋白H1密集- 组蛋白具有抑制性的修饰Department of Medical GeneticsDepartment of Medical Genetics异染色质与常染色质常染色质组成型的异染色质端粒动粒染色体上基因沉默的区域染色体上基因活化的区域Department of Medical GeneticsDepartment of Medical Genetics组蛋白与DNA的结合1.保护遗传信息；2.控制遗传信息的表达。给定一段DNA序列，其和组蛋白组装成核小体时，有无规律？哪些区域结合组蛋白？Department of Medical GeneticsDepartment of Medical Genetics核小体的分布 A：有丝分裂间期的染色体纤维：30nm B：DNA链拉伸后核小体的分布Department of Medical GeneticsDepartment of Medical Genetics核小体 1. 链上的珠子+连接DNA: 200bp 2. 核心组蛋白； 3. 通过核酶切割DNA：直径11nm的核小体Department of Medical GeneticsDepartment of Medical Genetics核小体 (2) 1. 核心组蛋白：8个组蛋白的复合物； 2. 146bp的核心DNA； 3. 平均缠绕1.65圈。Department of Medical GeneticsDepartment of Medical Genetics核心组蛋白 A. 核心组蛋白：H2A, H2B, H3 & H4 B. 组蛋白的结构；C. 组蛋白二聚体的结构Department of Medical GeneticsDepartment of Medical Genetics核心组蛋白 (2) 二聚体：H3 & H4, H2A & H2BDepartment of Medical GeneticsDepartment of Medical Genetics核心组蛋白 (3) 四聚体 vs. 八聚体Department of Medical GeneticsDepartment of Medical Genetics核小体 DNA序列缠绕在核心组蛋白的八聚体上Department of Medical GeneticsDepartment of Medical Genetics核小体 核小体呈致密或疏松状态，形成30nm的染色体纤维Department of Medical GeneticsDepartment of Medical Genetics组蛋白H1 确定核小体的边界Department of Medical GeneticsDepartment of Medical Genetics核小体的分布 1. 8114bp的连接序列； 2. 序列特异性的DNA结合蛋白质结合裸露的DNA序列。Department of Medical GeneticsDepartment of Medical GeneticsDNase I DNase I与DNA双螺旋的小沟结合，并切断磷脂键；Department of Medical GeneticsDepartment of Medical GeneticsDNase Footprinting 当有组蛋白与DNA结合之后，可观察到不能被切割的部分Department of Medical GeneticsDepartment of Medical GeneticsNaked & nucleosomal DNATranscriptionfactorfootprintr DNA组装到核小体上能够阻止DNase I的切割r DNase I切割：平均间隔10bpDepartment of Medical GeneticsDepartment of Medical GeneticsQuesion1：组蛋白和DNA序列的结合有无规律？Department of Medical GeneticsDepartment of Medical GeneticsAnswer：Structure of Nucleosome核心组蛋白H1组蛋白其他组蛋白核心组蛋白H1组蛋白核心组蛋白Department of Medical GeneticsDepartment of Medical GeneticsDepartment of Medical GeneticsDepartment of Medical GeneticsQuestion 2：How is the interaction between histone & DNA OK, 每146 bp DNA 和组蛋白包裹形成核小体。对一给定DNA片段，从哪里开始包裹组蛋白？基因组上的一段DNA是随机的分布在核小体的任何位置？ 还是特定位置？Department of Medical GeneticsDepartment of Medical Genetics核小体定位：Nucleosome positioningRandom ？Department of Medical GeneticsDepartment of Medical Genetics核小体定位：Nucleosome positioningRegulated ？In vivoDepartment of Medical GeneticsDepartment of Medical GeneticsResults：定位不是随机的，存在内在定位机制Department of Medical GeneticsDepartment of Medical Genetics优先装配的核小体 内在定位机制：定位信号