Administrative Supplement: Surveying transcription factor pioneer interactions with nucleosomal DNA

许多研究把重点放在对基因组“部分清单”进行编目，包括转录本， 转录因子(TF)结合部位和染色质状态。转录调控网络 已经根据这些数据进行了推断，从而得出了金融监管机构擅长什么的模型 或者接近监管层级的顶端，而不是特定于血统或条件的TF，后者是 在这些监管机构的下游。然而，这些方法都不能直接识别哪些 因子参与不可及的染色质启动转录调控级联反应。 先锋因子是染色质可及性的关键，可由大多数转录因子结合 通过稳定地与核小体DNA结合(“先锋结合”)从而增加DNA 酶促染色质的可及性(‘先锋活性’)，允许顺序招募 不活跃染色质上的其他转录因子。通过为后续的顺应性法规要素启动 转录调控活动，先锋因子充当细胞的“守门人” 差异化。 尽管它们很重要，但人们对先锋因素知之甚少，而且只有少数人已经成为先锋 特色化的。在表征先锋因素方面的一个主要障碍是缺乏一个强大的、高度的 吞吐功能测定。在这个项目中，我们将开发一种名为先锋的新技术 高通量核小体工程阵列(PIONEAR)上的相互作用 先锋结合的特征。我们将使用PIONEAR分析来调查先驱者 几十个人类TF的相互作用。由PIONEAR检测确定的TFS展示先驱 结合将在体内进行评估，以在更广泛的范围内检查染色质的分解。 鉴定具有先锋活性的转录因子可能导致定向细胞的突破 分化和重新编程与针对肿瘤的改进治疗方法的发展 干细胞。

Numerous studies have focused on cataloging the genome `parts list', including transcripts, transcription factor (TF) binding sites, and chromatin states. Transcriptional regulatory networks have been inferred based on these data, leading to models of what TFs are master regulators at or near the top of the regulatory hierarchy versus lineage- or condition-specific TFs, which are downstream of those regulators. However, none of these approaches directly identifies which factors engage inaccessible chromatin to initiate the transcriptional regulatory cascades. Pioneer factors serve as keys to chromatin accessibility for binding by the majority of TFs in a cell, by binding stably to nucleosomal DNA (`pioneer binding') and thus increase the DNA enzymatic accessibility of the chromatin (`pioneer activity'), allowing the sequential recruitment of other TFs on inactive chromatin. By priming cis regulatory elements for subsequent transcriptional regulatory activity, pioneer factors serve as `gatekeepers' to cellular differentiation. Despite their importance, little is known about pioneer factors, and only a handful have been characterized. A major hurdle in characterization of pioneer factors is the lack of a robust, high- throughput functional assay. In this project, we will develop a new technology, termed Pioneer Interactions On Nucleosomal Engineered ARrays (PIONEAR), for high-throughput characterization of pioneer binding. We will use PIONEAR assays to survey the pioneer interactions of dozens of human TFs. TFs identified by PIONEAR assays to exhibit pioneer binding will be evaluated in vivo to examine chromatin decompaction on a broader scale. Identification of TFs that exhibit pioneer activity may lead to breakthroughs in directed cellular differentiation and reprogramming and the development of improved therapies to target cancer stem cells.