Mechanisms controlling binding site selection of ETS family transcription factors

ETS家族转录因子（TF） PU.1是造血室的原型主调节因子。它与白血病有关，并且是几种血细胞谱系正常产生所必需的。控制PU.1在与核小体和其他染色质相关蛋白竞争中进入和选择其结合位点的机制仅部分被了解，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外和体内许多不同细胞类型的dna结合，这些细胞类型具有天然或异位的PU.1表达。我们发现在体外，PU.1与DNA的结合受到表观遗传和染色质的限制。然而，在体内，PU.1的异位瞬时诱导导致染色质的广泛重塑（在核小体上，而不是在基因组水平上）和伴侣tf的重新分配。这两种现象都需要PU.1的n端酸性活化结构域及其招募SWI/SNF重塑复合物的能力。目前的应用旨在继续这项工作，进一步表征PU.1的染色质和重塑器相互作用，并确定它们在造血中的功能相关性，以及与其他ETS家族因子的比较。这个项目的结果将推进我们对造血和一般情况下基因调控的基础过程的认识。从更广泛的意义上说，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发生的机制有关

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