Mechanism of Epigenetic Inheritance

在真核细胞中，基因组DNA被包装到染色质中，染色质编码表观遗传信息并维持细胞内的遗传信息。 基因组完整性染色质进一步组织成不同的功能结构域，如异染色质和异染色质。 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 在细胞周期的S期遗传是染色质中最具挑战性的问题之一， 表观遗传场这个复杂过程的“第一步”是复制的DNA组装成核小体 在一个与正在进行的DNA合成密切相关的过程中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，并进行了多项重大研究。 对这一进程的贡献。然而，如何亲本组蛋白（H3-H4）2四聚体，表观遗传的主要载体， 修饰，转移到复制DNA仍然知之甚少，这阻碍了我们对DNA的理解。 将表观遗传信息传递给子细胞。理解父母的主要挑战 组蛋白（H3-H4）2组装缺乏跟踪这一过程的方法。我们开发了eSPAN （富集和测序蛋白质相关新生DNA）方法，该方法可以辨别蛋白质 结合酵母和小鼠胚胎干细胞中DNA复制叉的前导链或滞后链。 该方法使得有可能鉴定在亲本组蛋白（H3-H4）的核小体组装中起作用的因子。 H4）2.此外，我们发现，在亲代组蛋白转移中有缺陷的细胞损害了对 内源性逆转录病毒（ERVs），通常通过基于异染色质的逆转录酶沉默的重复DNA元件， 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加。 在这个提议中，我们将阐明亲本（H3-H4）2重组成 核小体在酵母和小鼠ES细胞中的DNA复制，并确定如何在这种缺陷， 过程影响ERV消音。总之，这些研究将解决有关染色质的基本问题 复制和表观遗传，同时也提供了一个主要的表观遗传机制的新见解 增强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.