Mechanism of Epigenetic Inheritance

在真核细胞中，基因组DNA被包装成染色质，该染色质编码表观遗传信息并维持 基因组完整性。染色质进一步被组织成不同的功能区，如异染色质和 常染色质，含有不同的翻译后组蛋白修饰(PTM)。不同的染色质状态 都是在S阶段遗传的细胞周期中最具挑战性的问题之一，在染色质和 表观遗传领域。这一复杂过程的“第一步”是将复制的DNA组装成核小体。 在一个与正在进行的DNA合成紧密耦合的过程中，同时使用亲本和新合成的组蛋白。 我们一直在研究DNA复制后核小体是如何形成的，并已经做出了多个主要的 对这一进程的贡献。然而，亲代组蛋白(H3-H4)2四聚体是表观遗传学的主要载体 修饰，转移到复制的DNA仍然知之甚少，这阻碍了我们对 将表观遗传信息传递到子代细胞。理解父母的主要挑战 组蛋白(H3-H4)2的组装缺乏跟踪这一过程的方法。我们已经开发了eSPAN (浓缩和测序蛋白质相关的新生DNA)方法，可以区分蛋白质是否 结合在酵母和小鼠胚胎干细胞中领先或滞后的DNA复制叉链。 这种方法使鉴定在亲代组蛋白(H3-H3-)核小体组装中起作用的因子成为可能。 H4)2.此外，我们还发现，在亲代组蛋白转移中存在缺陷的细胞会抑制 内源性逆转录病毒(ERV)，一种重复的DNA元件，通常通过基于异染色质的 机制。其他研究表明，ERV在癌细胞中的重新激活导致对免疫治疗的反应增强。 在这项建议中，我们将阐明亲本(H3-H4)2重组为 在酵母和小鼠ES细胞中DNA复制后的核小体，并确定这一缺陷如何 流程影响ERV静音。这些研究将共同解决有关染色质的基本问题。 复制和表观遗传，同时也提供了对主要表观遗传机制的新见解 这增强了癌细胞对免疫疗法的反应。

In eukaryotic cells, genomic DNA is packaged into chromatin that encodes epigenetic information and maintain genome integrity. Chromatin is further organized into distinct functional domains, such as heterochromatin and euchromatin, that contain different post-translational histone modifications (PTM). How different chromatin states are inherited during S phase of the cell cycle is one of the most challenging questions in the chromatin and epigenetic fields. The “first” step in this complex process is the assembly of replicated DNA into nucleosomes using both parental and newly-synthesized histones in a process that is tightly coupled to ongoing DNA synthesis. We have been studying how nucleosomes are formed following DNA replication and have made multiple major contributions to this process. However, how parental histone (H3-H4)2 tetramers, the primary carrier of epigenetic modifications, are transferred to replicating DNA is still poorly understood, which hinders our understanding of the transmission of epigenetic information into daughter cells. The major challenge to understanding parental histone (H3-H4)2 assembly is a lack of methods to track this process. We have developed the eSPAN (enrichment and Sequencing Protein- Associated Nascent DNA) method that can discern whether a protein binds to leading or lagging strands of DNA replication forks in both yeast and mouse embryonic stem (ES) cells. This method makes it possible to identify factors that function in nucleosome assembly of parental histone (H3- H4)2. Moreover, we discovered that cells defective in parental histone transfer compromise the repression of endogenous retrovirus (ERVs), repetitive DNA elements that are normally silenced via a heterochromatin-based mechanism. Others show that ERV reactivation in cancer cells leads to increased response to immunotherapy. In this proposal, we will elucidate the molecular mechanisms whereby parental (H3-H4)2 are reassembled into nucleosomes following DNA replication in yeast and mouse ES cells and determine how deficiencies in this process impact ERV silencing. Together, these studies will address fundamental questions regarding chromatin replication and epigenetic inheritance, while also providing novel insights into a major epigenetic mechanism that boosts the response of cancer cells to immunotherapy.