Nuclear Pore Complexes As Scaffolds For Genome Architecture And Epigenetic Maintenance

核孔复合体（NPC）是一种核被膜， 嵌入的多组分复合物，介导细胞核和细胞核之间的分子运输， 细胞质除了它们在运输中的经典功能之外，NPC组分（Nups）已经被 通过与基因组结合参与转录调控。然而， 转录是由Nups控制的，以及Nups的染色质结合作用如何有助于后生动物的转录。 目前发展尚不清楚。我们鉴定了多个NUP与数百个启动子的结合， 以及果蝇基因组中的增强子，并发现了NPC在 增强子-启动子环的形成。具体来说，我们确定Nup98是 在由发育激素蜕皮激素激活的基因处形成增强子-启动子环。 在功能上，我们发现Nup98介导的增强子-启动子环的缺失影响了启动子的表达。 对随后的激活或转录记忆的反应。有趣的是，蜕皮激素调控基因 活化前后与核孔稳定相关，表明后生动物NPC可以 可以用作等待未来激活事件的基因的组织支架。所有这些 这些发现暗示Nups是一类新的增强子结构蛋白，并表明， 增强子-启动子环通过核孔结合的稳定化构成了表观遗传的机制， 上维护我们预测核孔的这种功能将与基因调控高度相关 在后生动物的发育过程中。为了能够研究Nups在基因组组织中的作用， 发育基因调控，我们首先计划确定NUP介导的 增强子-启动子环。因此，在目标1中，我们将定义哪些Nup和哪些其他架构 蛋白质参与蜕皮激素诱导的基因组环的建立。此外，我们计划 鉴定足以连接NPC或环所必需的DNA元件 稳定化在目标2中，我们提出定义Nup介导的形成与 增强子-启动子环和转录激活和记忆，通过识别染色质变化 这是循环的特定结果。此外，我们将研究Nups对 在发育过程中维持果蝇组织中的基因组环，并确定一套全面的 由NUPS调控的基因组接触。这些实验有望扩大我们的 基因组结构，基因表达和核的驱动力和原则的知识 孔隙生物学

The Nuclear Pore Complex (NPC) is a nuclear envelope embedded multi-component complex, which mediates transport of molecules between the nucleus and the cytoplasm. In addition to their classical function in transport, NPC components (Nups) have been implicated in transcriptional regulation via binding to the genome. Yet what regulatory steps of transcription are controlled by Nups and how chromatin-binding roles of Nups contribute to metazoan development is currently unclear. We identified the binding of multiple Nups to hundreds of promoters and enhancers in the Drosophila genome, and discovered a previously unreported role of the NPC in the formation of enhancer-promoter loops. Specifically, we identified Nup98 to be required for the formation of an enhancer-promoter loop at a gene activated by a developmental hormone ecdysone. Functionally, we found that the loss of Nup98-mediated enhancer-promoter loop affected the primed response to subsequent activation or transcriptional memory. Interestingly, ecdysone-regulated genes stably associated with nuclear pores before and after activation, suggesting that metazoan NPCs can be utilized as an organizing scaffold for genes awaiting future activation events. Together, these findings implicate Nups as a new class of architectural proteins for enhancers and suggest that stabilization of enhancer-promoter loops by nuclear pore binding constitutes a mechanism of epigenetic maintenance. We project that this function of the nuclear pore will be highly relevant to gene regulation during metazoan development. To be able to investigate the genome- organizing role of Nups in developmental gene regulation, we first plan to identify molecular determinants of Nup-mediated enhancer-promoter looping. Thus, in Aim 1, we will define which Nups and which other architectural proteins participate in the establishment of ecdysone- induced genomic loops. Additionally, we plan to identify DNA elements that are sufficient to tether to the NPC or that are necessary for loop stabilization. In Aim 2, we propose to define the relationship between formation of Nup-mediated enhancer-promoter loops and transcriptional activation and memory, by identifying chromatin changes that occur as a specific consequence of looping. Furthermore, we will examine the effect of Nups on maintenance of genomic loops in fly tissues during development and identify a comprehensive set of genomic contacts that are regulated by Nups. Together, these experiments are expected to expand our knowledge of the driving forces and principles of genome architecture, gene expression and nuclear pore biology.