53BP1 regulates genome biology and cellular physiology through liquid phase separation

核DNA的功能不仅取决于其序列，还取决于其三维结构 (3D)结构。真核生物中的一种特殊类型的dna被称为异染色质，指的是 细胞核内有密集的DNA结构。异染色质在包括DNA在内的基因组功能中起着关键作用 结构维持、染色体分离、表观遗传、DNA复制、修复和 抄写。最近，越来越多的证据表明，一种名为液体的新生物过程参与其中。 液相分离在异染色质的形成和作用。液-液相分离，其 概念借用自聚合物科学，是一种独特的过程，涉及到 当蛋白质和核苷酸的浓度达到阈值时，由蛋白质和核苷酸形成的无膜液滴。 这些液滴使基于蛋白质的功能性细胞器能够在 细胞隔间遵循环境提示。因此，液-液相分离促进了我们的 了解基本的细胞信息处理、细胞动态平衡和细胞生理学。 最近，我们出人意料地发现了一个新的调节异染色质完整性的角色，人53BP1 通过液-液相分离。53BP1以前被认为是调节DNA的关键角色 双链断裂修复。然而，我们发现53BP1在结构和结构上的保护作用 异染色质的功能与其在DNA双链断裂修复中的典型活性不同。因此， 我们的研究为这种重要的蛋白质在信号、生物学和细胞方面开辟了一个新的研究范式 生理学。这项提议目标是通过解决几个尚未回答的问题来建立这一新的研究领域 关于53BP1这一新功能的重要问题。其中包括53BP1的分子基础 形成液滴及其在生物学、基因组生物学和细胞生理学中的意义。我们已经使用了 用质谱仪鉴定53BP1形成的液滴中的成分。我们将审问他们 此应用程序中的函数。通过组建一个由分子和生物科学领域的专家组成的跨学科团队 细胞生物学、蛋白质组学、计算生物信息学和下一代测序，我们将使用 结合细胞生物学、分子、生化、遗传、形态和化学方法 回答这些问题。我们的研究将阐明53BP1以前未被描述的功能和一种新的 53BP1和异染色质之间的相互作用并确定它们对基因组稳定性的影响，促进我们的 了解基本的细胞信息处理、细胞动态平衡和细胞生理学。

The function of nuclear DNA is not only determined by its sequence, but also depends on its three dimensional (3D) structure. A particular type of DNA in eukaryotes is called heterochromatin, which refers to as tightly packed DNA structure in the nucleus. Heterochromatin plays a critical role in genome function including DNA structural maintenance, chromosome segregation, epigenetic inheritance, DNA replication, repair and transcription. Recently, increasing evidence suggests the involvement of a new biological process called liquid- liquid phase separation in the formation and function of heterochromatin. Liquid-liquid phase separation, whose concept was borrowed from polymer sciences, is a unique process that involves the formation of membraneless liquid droplets by proteins and nucleotides when their concentration have reached a threshold. These liquid droplets enable the assembly and disassembly of functional protein-based organelles within a cellular compartment following environmental cues. Hence, liquid-liquid phase separation has facilitated our understanding of fundamental cellular information processing, cellular homeostasis, and cellular physiology. Recently, we unexpectedly identified a new player, human 53BP1, in regulating the heterochromatin integrity through liquid-liquid phase separation. 53BP1 was previously known as a critical player in regulating the DNA double strand break repair. However, we discovered that the protective role of 53BP1 in both the structure and the function of heterochromatin is distinct from its canonical activity in DNA double strand break repair. Hence, our studies opened a new research paradigm for this important protein in signaling, biology and cellular physiology. The goal of this proposal is to establish this new research field by addressing several unanswered important questions regarding this new function of 53BP1. These include the molecular basis by which 53BP1 forms the liquid droplets and its significance in biology, genome biology, and cellular physiology. We have used mass spectrometry to identify components in the liquid droplets formed by 53BP1. We will interrogate their functions in this application. By assembling an interdisciplinary team consisting of experts on molecular and cellular biology, proteomics, computational bioinformatics, and next generation sequencing, we will use a combination of cell biological, molecular, biochemical, genetic, morphological, and chemical approaches to answer these questions. Our studies will illustrate a previously uncharacterized function of 53BP1 and a novel interplay between 53BP1 and heterochromatin and determine their impact on genome stability, facilitating our understanding of fundamental cellular information processing, cellular homeostasis, and cellular physiology.