Analyses of transcription factors related to megakaryocyte differentiation and maturation.

我们之前已经确定了负责巨核细胞特异性表达PF4基因的顺式元件和与该元件结合的蛋白质。在本研究中，我们研究了与这些蛋白相关的usf和AML-1的功能。我们发现这些转录因子刺激了PF4基因的表达。我们进一步研究了AML-1的生物学功能。虽然我们可以在包括AML-1在内的转录复合体中检测到ETS-1蛋白，但我们没有发现CBFβ在复合体中上调AML-1的转录活性。接下来我们研究了AML-1在巨核细胞分化中的功能。通过RNAi敲除AML-1的实验发现，AML-1在巨核形成早期促进巨核细胞的分化和成熟。然而，AML-1在巨核形成后期抑制分化。我们还研究了AML-1突变与家族性血小板疾病（FPD）之间的关系。研究了AML-1突变体对PF4基因表达的转录活性。我们发现某些AML-1突变体不仅降低了自身的转录活性，而且抑制了野生型AML-1的转录。进一步的分析表明，这些突变体抑制了ETS-1向细胞核的转运。这些结果为未来的FPD研究提供了重要的信息。

We have previously determined the cis-element that is responsible for the megakaryocyte specific expression of the PF4 gene and the proteins that bind to this element. In this study, we investigated the function of USFs and AML-1 which were involved in these proteins. We found that these transcription factors stimulated the expression of the PF4 gene. We further studied the biological function of AML-1. Although we could detect ETS-1 protein in the transcriptional complex including AML-1, we could not find CBFβ which up-regulated the transcriptional activity of AML-1 in the complex. We next investigated the function of AML-1 for the megakaryocyte differentiation. The knock down experiments of AML-1 by using RNAi revealed that AML-1 promoted the megakaryocyte differentiation and maturation at the early stage of megakaryopoiesis. However, AML-1 repressed the differentiation at the late stage of megakaryopoiesis.We also investigated the relationship between AML-1 mutations and familial platelet disorder (FPD). The transcriptional activities of AML-1 mutants on the PF4 gene expression were studied. We found that a certain AML-1 mutants not only diminished their own transcriptional activities but also inhibited the transcription by the wild type AML-1. Further analyses revealed that these mutants inhibited the transport of ETS-1 to the nucleus. These results provide us important information for the future approaches to the FPD research.