Molecular Analysis of Maturation Arrest Mechanism of Myeloid Leukemogenesis

我们一直在利用髓系标志基因、细胞周期相关基因和转录因子基因对髓系白血病发生的成熟停滞机制进行分子分析。首先，我们从慢性粒细胞白血病患者的G-CSF刺激的白血病细胞中克隆了一个新的髓系细胞标志基因gig-1(G-CSF可诱导基因-1)。结果表明，GIG-1基因在髓系细胞中表达于mRNA和蛋白水平。这个新基因在成熟细胞的蛋白质水平上有更多的表达。电子显微镜结果显示该蛋白在微粒体中定位。该新基因与其他髓系特异性标志基因碱性磷酸酶、髓过氧化物酶、防御素的表达对于分析成熟停滞的分子机制具有重要意义。其次，我们试图分析导致髓系细胞系成熟停滞的第一个事件。我们特别关注PEBP2α和PEBP2β基因，DNA结合和DNA非结合转录调控基因，形成异源二聚体，它们都被认为与白血病的发生密切相关。PEBP2基因敲除小鼠的胚胎显示出严重的造血现象，包括髓系细胞成熟停滞。由于PEBP2α基因的缺陷也被报道与基因敲除小鼠的造血抑制密切相关，这两个分子都被认为是髓系白血病成熟停滞的责任分子之一。正常对应基因的使用可能对某些带有PEBP2α或PEBP2β基因突变的髓系白血病有用。我们还研究了包括Evi-1在内的其他转录因子和细胞周期特异性分子的作用，以阐明这些分子在髓系白血病细胞成熟停滞中的作用。

We have been focusing on the molecular analysis of maturation arrest mechanism underlying the myeloid leukemogenesis using myeloid marker genes, cell cycle related genes and trancriptional factor genes. First of all, we have cloned a novel myeloid cell marker gene of GIG-1 (G-CSF inducible gene-1) from G-CSF stimulated leukemia cells from CML patients. The results demonstrated that GIG-1gene was expressed in myeloid lineage cells at the levels of mRNA and protein. This novel gene was paricularly expressed more in matured cells at protein levels. The elecromicroscopic results revealed the microsomal localization of this protein. The expression of this novel gene together with other myeloid specific marker genes of alkaline phosphatase, myeloperoxidase, defensin are very important to analyze the molecular mechanisms of maturation arrest. Second, we tried to analyze the first event which induced the maturation arrest of myeloid cell lineage. Particulary we focused on PEBP2 alpha and PEBP2 beta genes, DNA binding and DNA nonbinding transcriptional regulating genes respectively, forming heterodimers and both of them are considered strongly involoved in leukemogenesis. The embryos of knockout mice of the PEBP2 beta revealed the severe pictures of hematopoiesis including maturation arrest of the myeloid cells. As the defect of PEBP2 a gene was also reported to be strongly involved in the suppressed hematopoiesis in knockout mice, both of these molecules are consiered to be one of the responsible molecule of maturation arrest found in myeloid leukemia. The use of the normal counterpart genes might be useful for some types of myeloid leukemia with the genetic disruptios of PEBP2 alpha or PEBP2 beta. We also studied the roles of othere transcriptional factors including Evi-1 and cell cycle specific molecules for elucidating the roles of these molecules in the maturation arrest of myeloid leukemia cells.