| Research Abstract |
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.
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