Mechanisms controlling binding site selection of ETS family transcription factors

Ets家族转录因子(Tf)PU1是一种典型的造血室主调控因子。它与白血病有关，是几种血细胞系正常生成所必需的。控制PU1与核小体和其他染色质相关蛋白竞争获得和选择其结合部位的机制只有部分了解，但显然是造血的基础。在之前DFG资助的一个项目中，我们系统地分析了体内和体外对多种不同类型细胞的DNA结合，这些细胞具有天然或异位表达的PU1。我们发现，在体外，PU1与DNA的结合受到表观遗传和染色质的限制。然而，在体内，PU1的异位瞬时诱导导致染色质的广泛重塑(在核小体上，但不在基因组水平上)和伴侣TF的重新分布。这两种现象都需要PU.1‘S N端酸性激活结构域及其募集SWI/SnF重塑复合体的能力。目前的应用旨在继续这项工作，以进一步表征PU1的染色质和重构体相互作用，并确定它们在造血中的功能相关性，并与其他ETS家族因子进行比较。这个项目的结果将促进我们对一个过程的了解，这个过程是造血和一般情况下基因调控的基础。在更广泛的意义上，考虑到ETS因子在白血病中的作用，我们的发现也可能与白血病的发生机制有关

The ETS family transcription factor (TF) PU.1 is a prototypic master regulator of the hematopoietic compartment. It has been implicated in leukemia and is required for the normal generation of several blood cell lineages. The mechanisms controlling PU.1 access to and selection of its binding sites in competition with nucleosomes and other chromatin associated proteins is only partially understood, but clearly fundamental for hematopoiesis. In a previous DFG-funded project, we systematically analyzed DNA-binding in vitro and genome-wide in vivo across many different cell types with native or ectopic PU.1 expression. We found that in vitro, PU.1 binding to DNA is subject to both epigenetic and chromatin constraints. However, in vivo, the ectopic, transient induction of PU.1 lead to the extensive remodeling of chromatin (on nucleosome, but not on genome level) and redistribution of partner TFs. Both phenomena required PU.1’s N-terminal acidic activation domain and its ability to recruit SWI/SNF remodeling complexes. The current application aims at continuing this work to further characterize chromatin and remodeler interactions of PU.1 and to determine their functional relevance in hematopoiesis, also in comparison to other ETS family factors. The results of this project will advance our knowledge of a process that is fundamental to gene regulation in hematopoiesis and in general. In a broader sense and given the role of ETS-factors in leukemia, our findings may also relate to mechanisms of leukemogenesis