RUI: Investigating enhancer grammar that underlies naive-state pluripotency

尽管经过了几十年的研究，从遗传信息中预测增强子的功能仍然是一个挑战。增强子是基因组中控制基因何时何地表达的序列，在多细胞生物的发育过程中具有深远的作用。虽然它们不编码蛋白质，但增强子所包含的信息被编码为转录因子（TFs）的结合位点，而转录因子是基因调控的关键蛋白质。人们认为，增强子功能的关键因素是语法，或TF结合位点的特征，如类型、数量、结合亲和力和排列。然而，关于增强子语法的原理以及它们如何构成基因调控机制的基础，仍然存在许多问题。对增强子的深入了解将有助于我们从遗传信息中预测表型，并可应用于其他领域，如医学和农业。该项目将研究naïve-state多能干细胞中的增强子语法，这代表了哺乳动物发育的最早阶段。除了推进基因调控如何编码到基因组中的知识外，这项工作每年将吸引25-50名本科生进行指导，调查和原创性研究，为科学事业做准备。为了研究naïve-state特异性增强子功能的语法约束，本项目将重点研究naïve-state基因Klf4的增强子，这些增强子包含tf OCT4、SOX2、ESRRB和STAT3的结合位点。初步研究表明，低亲和力的TF结合位点对一种Klf4增强子的naïve-state特异性功能至关重要。为了阐明这种结合亲和力约束在转录激活机制中的作用，该项目将利用分子方法来测量优化该增强子中TF结合位点的效果。先前的研究也表明，TF以等级顺序与Klf4增强子结合，这表明TF结合位点的排列是促进增强体组装的关键，特别是Klf4增强子上TF之间的相互作用。为了解决这些问题，本研究将结合报告基因分析、基因编辑和分子技术。最后，本项目将把这些知识和先前对Klf4增强子的研究应用于其他naïve-state特异性增强子。生物信息学和分子生物学技术的结合将被用来识别和分析推定的naïve-state特异性增强子。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Despite decades of research, it remains a challenge to predict enhancer functions from genetic information. Enhancers are sequences in genomes that control when and where genes are expressed and have profound roles during development of multicellular organisms. While they do not code for proteins, the information that enhancers contain is encoded as binding sites for transcription factors (TFs), which are key proteins in gene regulation. It is thought that a key contributor to enhancer function is grammar, or the characteristics of TF binding sites, such as type, number, binding affinities, and arrangement. However, there are still many questions about the principles of enhancer grammar and how those underlie mechanisms for gene regulation. A deeper understanding of enhancers will help us predict phenotypes from genetic information and can be applied in other areas, such as medicine and agriculture. This project will study enhancer grammar in naïve-state pluripotent stem cells, which represent the earliest stages of mammalian development. In addition to advancing knowledge about how gene regulation is encoded into the genome, this work will engage 25-50 undergraduate students per year in mentored, investigative, and original research in preparation for science careers.To investigate grammatical constraints that underlie naïve-state specific enhancer function, this project will focus on the enhancers for the naïve-state gene Klf4, which contain binding sites for the TFs OCT4, SOX2, ESRRB and STAT3. Preliminary work has indicated that low-affinity TF binding sites are critical for the naïve-state specific function of one Klf4 enhancer. To illuminate the role of this binding affinity constraint in transcription activation mechanisms, this project will utilize molecular approaches to measure the effects of optimizing TF binding sites in this enhancer. Prior studies also have shown that TFs bind to the Klf4 enhancers in a hierarchical order, suggesting that the arrangement of TF binding sites is key to facilitate enhanceosome assembly, particularly interactions among TFs at the Klf4 enhancers. To address these questions, this research will utilize a combination of reporter assays, gene editing, and molecular techniques. Lastly, this project will apply knowledge from these and prior studies of the Klf4 enhancers to other naïve-state specific enhancers. A combination of bioinformatics and molecular biology techniques will be employed to identify and analyze putative naïve-state specific enhancers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.