Characterizaton of the chromatin remodelling activity of the transcription factor c-Myb

转录因子c-Myb在造血细胞的增殖、分化和凋亡的控制中起关键作用，并且与白血病和某些非造血肿瘤（如乳腺癌和结肠癌）的发展有关。虽然一些Myb调控基因是已知的，几个蛋白质相互作用和合作与Myb已被确定，我们目前只有一个相当不完整的图片如何Myb刺激其靶基因的表达在其天然的，染色质嵌入状态。这样的图片将显着提高我们对Myb在造血细胞中的作用的理解，并将有助于开发Myb的小分子抑制剂。该项目的总体目标是了解Myb和转录机制之间的分子相互作用，这些机制与Myb靶基因在其天然染色质化状态下的转录调控相关。在我们的初步工作中，我们研究了Myb对鸡mim-1基因（一种特征良好的Myb靶基因）染色质结构的影响，并确定了Myb反式激活结构域内的一个高度保守区域，该区域在Myb的染色质重塑中起着至关重要的作用。我们的工作表明，这个区域，称为染色质重塑结构域（CRD），参与蛋白质-蛋白质相互作用与Myb本身以及与几个染色质重塑蛋白，包括蛋白质精氨酸甲基转移酶PRMT 4，组蛋白乙酰转移酶TIP 60和Menin，衔接蛋白混合谱系白血病（MLL）组蛋白甲基转移酶复合物。在这个项目中，我们计划详细探索这个结构域及其分子相互作用如何控制Myb作为转录因子的活性。具体来说，我们将表征由CRD和Myb的其他部分介导的分子内相互作用，采用蛋白质组学方法来确定CRD的新的相互作用伙伴，并研究CRD与Menin，TIP 60和PRMT 4相互作用的功能相关性。总的来说，我们希望这项工作将大大推进我们对Myb作为转录因子的功能的理解。我们还期望，CRD的分子相互作用的表征，从长远来看，允许我们建立用于开发Myb功能的治疗性抑制剂的测定系统。

The transcription factor c-Myb plays a key role in the control of proliferation, differentiation and apoptosis of hematopoietic cells and has been implicated in the development of leukemia and of certain non-hematopoietic tumors, such as breast and colon cancer. Although a number of Myb-regulated genes are known and several proteins interacting and cooperating with Myb have been identified, we have presently only a rather incomplete picture of how Myb stimulates the expression of its target genes in their native, chromatin-embedded state. Such a picture would significantly improve our understanding of the role of Myb in hematopoietic cells and would aid in the development of small molecule inhibitors of Myb. The overall goal of this project is to understand the molecular interactions between Myb and the transcriptional machinery that are relevant for the transcriptional regulation of Myb target genes in their native, chromatinized state. In our preliminary work we have studied the impact of Myb on the chromatin structure of the chicken mim-1 gene, a well-characterized Myb target gene, and identified a highly conserved region within the Myb transactivation domain, that plays a crucial role in chromatin remodelling by Myb. Our work shows that this region, referred to as chromatin remodelling domain (CRD), participates in protein-protein interactions with Myb itself as well as with several chromatin remodelling proteins, including the protein arginine methyl-transferase PRMT4, the histone acetyl-transferase TIP60 and Menin, an adaptor protein Mixed lineage leukemia (MLL) histone methyl-transferase complexes. In this project we plan to explore in detail how this domain and its molecular interactions control the activity of Myb as a transcription factor. Specifically, we will characterize intramolecular interactions mediated by the CRD and other parts of Myb, employ proteomic approaches to identify novel interaction partners of the CRD, and investigate the functional relevance of the interaction of the CRD with Menin, TIP60 and PRMT4. Overall, we expect that this work will significantly advance our understanding of the function of Myb as a transcription factor. We also expect that the characterization of the molecular interactions of the CRD will, on the longer run, permit us to establish assay systems for the development of therapeutic inhibitors of Myb function.