MOLECULAR BASIS OF STEM CELL SYSTEMS AND ITS APPLICATION

为了揭示干细胞系统中的分子分化机制，我们建立了一种新的实验策略，将ES细胞体外分化方法(OP9系统)和Tet-off条件基因表达方法相结合。利用该系统，我们分析了GATA-1、GATA-2、RUNX-1和FOG-1等转录因子和辅助因子在造血分化过程中的作用。当一种造血型锌指蛋白GATA-2过度表达时，巨噬细胞分化被阻断，分化转换为红系或巨核系。以及决心。红系细胞或巨核细胞由GATA-2表达的时间决定。此外，组蛋白去乙酰酶(HDAC)抑制剂TSA(曲古抑素A)使巨核细胞向红系的分化发生倾斜。进一步的分析表明，另一种造血转录因子PU.1的表达水平对红系或巨核系的谱系决定起着至关重要的作用。目前，其他转录因子的功能正在研究中。

In order to reveal the molecular differentiation mechanisms in stem cell systems, we established a novel experimental strategy combining an ES cell in vitro differentiation method (OP9 system) and Tet-off conditional gene expression method. Using the system, we analyzed the functions of transcriptional factors and co-factors involved in hematopoietic differentiation such as GATA-1, GATA-2, Runx-1 and FOG-1.During the course of hematopoietic differentiation in the presence of M-CSF (macrophage-colony stimulating factor), macrophages are preferentially produced. When a hematopoietic zinc finger protein, GATA-2, is over-expressed, macrophage differentiation is blocked and differentiation switch to erythroid or megakaryocytic lineages occurs. And the determination to. erythroid cells or megakaryocytes were determined by the timing of GATA-2 expression. In addition, TSA (trichostatin A), an HDAC (histone de-acetylase) inhibitor skewed the differentiation from megakaryocyte to erythroid lineage. Further analyses revealed that expression level of PU.1, another hematopoietic transcription factor, played crucial roles for the lineage determination to erythroid or megakaryocytic lineages.Now the functions of the other transcription factors are under investigation.