Interrogating YY1's role in chromatin organization during erythroid cell state transitions

项目摘要 染色质结构在指导基因表达和维持细胞同一性方面起着重要作用。 然而，关于基因组在关键的转变过程中如何重组仍有许多未知之处， 如细胞周期进程和细胞分化。 有丝分裂的标志是转录的全球停止，转录因子的驱逐，以及 大多数染色质结构溶解。在有丝分裂到G1期的转变过程中，新生细胞必须 因此，解决快速重建3D基因组组织的挑战，以忠实地反映 母细胞。而CTCF和粘附素介导的环挤出已被证明可以锻造一些染色质 循环，许多观察到的建筑特征不能用这种机制来解释。另一项重要的 在间期细胞的研究中，结构因子YY1被认为与增强子-启动子环有关。 然而，它的动力学和在染色质环形成中的作用在关键时刻还没有被探索。 在有丝分裂和G1期之间。我们的目标是表征YY1染色质的占用动力学，因为它与 染色质环的出现。我们将通过审问特定时间耗尽的影响来测试它的必要性 中期和进入G1期。我们还建议研究YY1的功能重要性- 通过表征有丝分裂耗竭引起的转录变化来调节环路的形成。 同样，YY1在造血过程中染色质组织中的作用也尚未明确。 YY1被提议作为开发所必需的循环的调节器，但之前的工作只是 专注于在有限的细胞类型中选择基因座。阐明YY1‘S参与的基因组重组 发展转变，我们将通过以下方式表征YY1绑定和相应的架构变化 生成红细胞成熟前后的高分辨率Micro-C图。我们还将严重耗尽 YY1在分化过程中，以测试其在红细胞中协调循环重新配置的必要性。 通过利用两个自然状态转换-细胞周期和红系分化-以及急性 降解系统，我们的目标是获得对基因组基本机制的新见解 组织。

Project Summary Chromatin structure plays an important role in instructing gene expression and maintaining cellular identity. However, much remains unknown regarding how the genome becomes reorganized during crucial transitions, such as cell cycle progression and cellular differentiation. Mitosis is marked by a global cessation of transcription, eviction of transcription factors, and the dissolution of most chromatin structure. During the mitosis to G1 phase transition, newly born cells must therefore address the challenge of rapidly re-establishing 3D genome organization that faithfully reflects that of the mother cell. While CTCF and cohesin-mediated loop extrusion has been shown to forge some chromatin loops, many observed architectural features cannot be explained by this mechanism. Another important architectural factor, YY1, has been implicated in enhancer-promoter loops in studies in interphase cells. However, its dynamics and role in chromatin loop formation has not been explored at the critical juncture between mitosis and G1 phase. We aim to characterize YY1 chromatin occupancy kinetics as it relates to the emergence of chromatin loops. We will test its necessity by interrogating effects of specifically timed depletion during metaphase and during G1 phase entry. We also propose to study the functional importance of YY1- mediated loop formation by characterizing transcriptional changes caused by mitotic depletion. Similarly, the role of YY1 in chromatin organization during hematopoiesis has yet to be clearly defined. YY1 has been proposed to be a regulator of loops essential for development, but previous work has only focused on select loci in limited cell types. To elucidate YY1’s involvement in genome reorganization during developmental transitions, we will characterize YY1 binding and corresponding architectural changes by generating high-resolution Micro-C maps before and after erythroblast maturation. We will also acutely deplete YY1 during differentiation to test its necessity in orchestrating looping reconfiguration in erythroblasts. By utilizing two natural state transitions – cell cycle and erythroid differentiation – as well as an acute degradation system, we aim to gain new insights into the fundamental mechanisms underlying genome organization.