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Molecular Mechanisms of Inhibition of Erythroid Differentiation by Overexpression of Ets Family Oncogenes in MEL cells

MEL细胞中Ets家族癌基因过表达抑制红系分化的分子机制

基本信息

批准号：
10470063
负责人：
OIKAWA Tsuneyuki
金额：
$ 1.28万
依托单位：
Sasaki Institute
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10470063/
关键词：
leukemia differentiation apoptosis transcription factor Ets family oncogene PU.1 GATA-1 CBP 白血球細胞増殖分化

项目摘要

We previously reported that overexpression of PU.1, a member of ets family oncogenes, induces differentiation inhibition, growth arrest and apoptosis in murine erythroleukemia (MEL) cells treated with dimethylsulfoxide (DMSO) (Blood 89 : 1383-1393, 1997).In the present study, we have investigated molecular mechanisms of PU-.1-induced effects in MEL cells. Among several apoptosis-related proteins examined, expression of the Bcl-2 and c-Myc protein was significantly suppressed in PU.1-overexpressing MEL cells. Introduction of either bcl-2 or c-myc gene in the cells prevented the apoptosis, suggesting that down-regulation of the bcl-2 and c-myc genes is involved in PU.1-induced apoptosis in MEL cells. Furthermore, the DNA binding activity of GATA-1, an erythroid-specific transcription factor critical for survival of erythroid cells, was markedly reduced in PU.1-overexpressing MEL cells treated with DMSO. By using two-hybrid system, we found that physical and functional interactions between PU.1 and the coactivator CBP(CREB binding protein), suggesting that positive and negative cross-talk between transcription factors through limiting amount of CBP. Indeed, overexpression of c-myb inhibited PU.1-mediated transactivation. PU.1-induced growth arrest and apoptosis but not differentiation inhibition was prevented by overexpression of CBP in MEL cells. Overexpression of PU.1 not only inhibited erythroid differentiation but also promoted myelomonocytic differentiation of MEL cells. We have identified several novel genes associated with overexpression of PU.1 in MEL cells by the method of differential display. We are now cloning the genes to analyze their biological activities.

我们以前报道过，在用二甲基亚砜（DMSO）处理的鼠红白血病（MEL）细胞中，ets家族癌基因的成员PU-1的过表达诱导分化抑制、生长停滞和凋亡（Blood 89：1383-1393，1997）。在几个凋亡相关蛋白的检查，Bcl-2和c-Myc蛋白的表达显着抑制在PU.1过表达MEL细胞。在细胞中引入bcl-2或c-myc基因可以阻止细胞凋亡，这表明bcl-2和c-myc基因的下调与PU.1诱导的MEL细胞凋亡有关。此外，加塔-1的DNA结合活性，红系细胞的生存的关键红系特异性转录因子，在PU.1过表达MEL细胞与DMSO处理显着降低。利用双杂交系统，我们发现PU.1与共激活因子CBP（CREB结合蛋白）之间存在物理和功能上的相互作用，提示转录因子之间的正、负交互作用是通过限制CBP的量来实现的。事实上，c-myb的过表达抑制了PU.1介导的反式激活。在MEL细胞中，PU.1诱导的生长停滞和凋亡而不是分化抑制被CBP过表达所阻止。PU.1的过表达不仅抑制MEL细胞向红系分化，而且促进MEL细胞向粒单核细胞分化。我们通过差异显示方法鉴定了几个与MEL细胞中PU.1过表达相关的新基因。我们现在正在克隆这些基因以分析它们的生物活性。