The Role of Parental Histone Proteins in Early Development

摘要 卵母细胞和精子是终末分化的细胞，它们可以在受精后产生多细胞生物体。 尽管使用了相同的基因模板，几十年来，生物学家一直对这种现象的发生感到好奇 并帮助促进了对细胞表观基因组的理解。表观基因组由 组蛋白或DNA本身的几种类型的化学修饰。总的来说，这些 表观遗传修饰稳定基因表达模式并建立细胞特性。在体细胞中， 表观遗传状态通过许多有丝分裂来维持，但在生殖系和早期阶段基本上被清除。 胚胎，以确保适当的发展，和/或防止遗传获得的表观遗传信息 跨越几代人。尽管在胚胎和生殖细胞中发生了两波全基因组重编程， 在包括人类在内的各种生物体中已经观察到非遗传信息的遗传。这些 观察提出了一些基本的问题--配子是否将表观遗传信息传递给合子？ 跨代表观遗传携带者的分子本质是什么？一个合乎逻辑和合理的载体， 表观遗传记忆是组蛋白，但无论父母组蛋白是物理遗传还是有一个 由于技术和实验的限制，在胚胎发育中的功能作用仍然未知。 因此，为了克服这些挑战，我们开发了尖端的遗传和分子工具， 可视化和跟踪早期胚胎和最初几次分裂期间的母本和父本组蛋白。基于 根据以前的文献和我的初步数据，我假设母亲和父亲的组蛋白保留在 受精卵，并持续多次胚胎细胞分裂。为了解决这些问题，我将使用 小鼠遗传学组合，早期胚胎操作，免疫组织化学，单分子 分辨率成像技术。这些研究将提供基本的见解，是否组蛋白可以服务于 作为表观遗传记忆的信息载体。此外，完成这项工作将为我提供关键的 科学和技术培训，如我的培训计划所述，这将是成功职业生涯的基础 作为一个独立的科学家，研究决定我们早期发展的核心原则。

Abstract Oocytes and sperm are terminally differentiated cells that can give rise to a multicellular organism after fertilization despite using an identical genetic template. How this happens has intrigued biologists for decades and has helped spur advancements in the understanding of the cellular epigenome. The epigenome is comprised of several types of chemical modifications on either histone proteins or the DNA itself. Collectively, these epigenetic modifications stabilize gene expression patterns and establish cellular identity. In somatic cells these epigenetic states are maintained through many mitotic divisions, but are largely cleared in the germline and early embryos to ensure proper development, and/ or prevent the inheritance of acquired epigenetic information across generations. Despite the two waves of genome-wide reprogramming in embryos and germ cells, inheritance of non-genetic information has been observed in various organisms including humans. These observations have raised fundamental questions - Do gametes convey epigenetic information to the zygote? What is the molecular nature of an epigenetic carrier across generations? A logical and reasonable carrier of epigenetic memory are histone proteins, but whether the parental histones are physically inherited or have a functional role in embryonic development remains unknown due to technical and experimental limitations. Therefore, to overcome these challenges we have developed cutting edge genetic and molecular tools to visualize and track maternal and paternal histones in the early embryo and during the first few divisions. Based on previous literature and my preliminary data, I hypothesize that maternal and paternal histones are retained in the zygote, and persist across multiple embryonic cell divisions. To address these questions, I will use a combination of mouse genetics, early embryonic manipulations, immunohistochemical, single-molecule resolution imaging techniques. These studies will provide fundamental insights into whether histones can serve as informational carriers of epigenetic memory. Additionally, completion of this work will provide me with critical scientific and technical training, as outlined in my training plan, which will be foundational for a successful career as an independent scientist studying the core principles that dictate our early development.