MOLECULAR CORRELATES OF HOXB4 FUNCTION

造血干细胞包括非常小的一部分骨髓单核细胞，其保留自我更新以及受控分化为外周血的所有细胞成分的能力。赋予干细胞表型的分子信号和控制干细胞增殖和分化的机制尚未完全理解。同源异型盒基因HoxB 4在造血干/祖细胞中表达，但在更分化的细胞中不表达。一些不同的研究 研究者已经表明，HoxB 4在造血干细胞中的强制表达导致它们在体内和体外扩增的能力增强，而不诱导不良事件如白血病的发展。该提案的总体研究目标是利用目前新兴的基因组规模分析工具，研究HoxB 4在干细胞扩增中的分子作用机制。这些分析将包括各种技术，包括基因转移，然后诱导转移基因的表达，使用微阵列进行基因表达谱分析，染色质免疫沉淀，然后进行大规模筛选以鉴定基因组DNA中的HoxB 4结合位点，蛋白质-蛋白质相互作用的研究，重组嵌合融合蛋白的功能研究，通过RNAi抑制基因表达和蛋白质摄取实验。

Hematopoeitic stem cells comprise a very small faction of bone marrow mononuclear cells, which retain the capacity for self-renewal as well as controlled differentiation into all of the cellular elements of the peripheral blood. The molecular signals that confer the stem cell phenotype and the mechanisms that control stem cell proliferation and differentiation are not completely understood. The homeobox gene HoxB4 is expressed in hematopoietic stem/progenitor cells but not in more differentiated cells. Studies by a number of different investigators have shown that enforced expression of HoxB4 in hematopoietic stem cells leads to enhancement of their ability to expand, both in vivo and in vitro, without inducing adverse events such as the development of leukemia. The overall research goal of this proposal is to investigate the molecular mechanisms of action of HoxB4 in stem cell expansion, using currently emerging tools for genomic scale analysis. These analyses will include a variety of technologies, including gene transfer followed by induced expression of the transferred gene(s), gene expression profiling using microarrays, chromatin immunoprecipitation followed by large scale screening to identify HoxB4 binding sites in genomic DNA, study of protein-protein interactions, functional studies of recombinant chimeric fusion proteins, inhibition of gene expression by RNAi and protein uptake experiments.