The t(8;21) fusion protein, AML1/ETO, transforms NIH3T3 cells and activates AP-1
The t(8;21) fusion protein, AML1/ETO, transforms NIH3T3 cells and activates AP-1
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DOI：
10.1038/sj.onc.1202459
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发表时间：
1999-03-04
期刊：
影响因子：
8
通讯作者：
Nimer, SD
中科院分区：
文献类型：
--
作者：
Frank, RC;Sun, X;Nimer, SD
8; 21易位是人类急性髓性白血病中最常见的细胞遗传学异常，将21号染色体上的AML 1基因与8号染色体上的ETO基因连接，形成AML 1/ETO融合基因。然而，AML 1/ETO也可以激活BCL-2启动子并在体外引起增强的造血祖细胞自我更新，这表明融合蛋白具有独特的功能获得性。我们用NIH 3 T3细胞来测定AML 1/ETO的转化能力，并进一步表征其作用机制。NIH 3 T3细胞中AML 1/ETO的表达引起细胞类型特异性细胞死亡和细胞转化，其特征是表型变化、非贴壁依赖性生长和裸鼠肿瘤形成。相比之下，AML 1A、AML 1B或ETO的表达都没有改变细胞的正常生长模式。为了研究AML 1/ETO的转化机制，我们分析了活化、非贴壁生长和肿瘤形成的水平。磷酸化的c-Jun（ser 63）和AP-1复合物的其他成分，在各种AML 1/ETO相关蛋白的存在下。AML 1/ETO的表达增加了c-Jun-P（ser 63）的水平，并激活了AP-1依赖的转录，这被显性负性c-Jun蛋白的表达抑制。突变分析表明，AML 1/ETO中的runt同源结构域（RHD）和C末端转录抑制结构域是转化、激活c-Jun和增加AP-1活性所必需的。这些结果确立了t（8;21）融合蛋白的转化潜力，并将这种功能获得性特性与AP-1活性的调节联系起来。
The 8;21 translocation is the most common cytogenetic abnormality in human acute myelogenous leukemia, joining the AML1 gene on chromosome 21, to the ETO gene on chromosome 8, forming the AML1/ETO fusion gene, The AML1/ETO fusion protein has been shown to function mainly as a transcriptional repressor of AML1 target genes and to block AML1 function in vitro and in vivo. However, AML1/ETO can also activate the BCL-2 promoter and cause enhanced hematopoietic progenitor self-renewal in vitro, suggesting gain-of-functions unique to the fusion protein. We used NIH3T3 cells to determine the transforming capacity of AML1/ETO, and to further characterize its mechanism of action. Expression of AML1/ETO in NIH3T3 cells caused cell-type specific cell death, and cellular transformation, characterized by phenotypic changes, anchorage-independent growth, and tumor formation in nude mice, In contrast, neither expression of AML1A, AML1B or ETO altered the normal growth pattern of the cells, To investigate the mechanism of transformation by AML1/ETO, we analysed the levels of activated, phosphorylated c-Jun (ser63) and other constituents of the AP-1 complex, in the presence of various AML1/ETO related proteins. Expression of AML1/ETO increased the level of c-Jun-P (ser63), and activated AP-1 dependent transcription, which was inhibited by expression of a dominant-negative c-Jun protein. Mutational analysis revealed that the runt homology domain (RHD) and a C-terminal transcriptional repression domain in AML1/ETO are required for transformation, activation of c-Jun and increased AP-1 activity, These results establish the transforming potential of the t(8;21) fusion protein and link this gain-of-function property to modulation of AP-1 activity.