The differential regulation of target genes by transcription factor BACH 1 in erythroid and megakaryocytic cells.

目的大约10%的唐氏综合征（DS）新生儿出生时伴有类白血病反应，通常称为短暂性骨髓增生性疾病（TMD）。一部分TMD患者在其生命的前4年内会发展为恶性急性巨核细胞白血病（AMKL）。人BACH1基因定位于21号染色体上潜在的DS相关基因区域内。本研究的目的如下：第一，寻找转录因子BACH 1的新靶基因。第二，揭示BACH 1在红系和巨核细胞中的转录调控机制。第三，研究BACH 1基因在DS患者TMD和AMKL发生中的作用。结果我们建立了在红系和巨核细胞中表达人BACH 1基因的转基因小鼠。用胎肝细胞在含TPO的培养基中进行巨核细胞的体外培养，获得成功。接下来，我们使用从培养的巨核细胞和Ter 119阳性细胞提取的RNA，通过微阵列分析，分析了来自BACH1 Tg小鼠和野生同窝仔的红系和巨核细胞的基因表达。我们证实了先前报道的BACH1靶基因在BACH1 Tg小鼠的巨核细胞中消退。新靶基因的转录调控机制正在研究中。我们发现BACH1在红系和巨核细胞中对一些靶基因有不同的调控。我们正在研究BACH 1因子在这些基因中的调节元件中的结合。我们还成功地通过逆转录病毒感染将BACH 1基因转导到造血细胞系中，并在体外实验系统中分析了BACH 1的功能。

ObjectApproximately 10% of newborn babies with Down's syndrome (DS) are born with a leukemoid reaction commonly called transient myeloproliferative disorder (TMD). A portion of TMD patients will develop malignant acute megakaryoblastic leukemia (AMKL) during their first 4 years of life. The human BACH1 gene is localized to chromosome 21 within the potential DS-associated gene region. Objects in this research are as follows : First, finding novel target genes of the transcription factor BACH1. Second, disclosing the mechanism of the transcriptional regulation by BACH1 in erythroid or megakaryocytic cells. Third, investigating the contribution of BACH1 gene in developing TMD and AMKL in DS patients.ResultsWe established the transgenic (Tg) mice expressing human BACH1 gene in erythroid and megakaryocytic cells. We succeeded in culture of megakaryocytes in vitro using the fetal liver cells in the medium containing TPO. Next, we profiled the gene expression of erythroid and megakaryocytic cells derived from BACH1 Tg mice and wild littermates by micro array analysis using RNA extracted from cultured megakaryocytes and Ter119 positive cells. We confirmed the BACH1 target genes previously reported was regressed in megakaryocytes of BACH1 Tg mice. Mechanism of transcriptional regulation in novel target genes is being investigated. We found the some of BACH1 target genes were differentially regulated by BACH1 in erythroid and megakaryocytic cells. We are investigating the binding of BACH1 factor in the regulatory elements in these genes. We also succeeded in transducing the BACH1 gene to hematopoietic cell lines by retrovirus infection and analyzed the function of BACH1 in vitro experimetal systems.