Senyuk Vitalyi, Sinha Kislay K, Li Donglan, Rinaldi Ciro R, Yanamandra Sastry, Nucifora Giuseppina
Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
Cancer Res. 2007 Jun 15;67(12):5658-66. doi: 10.1158/0008-5472.CAN-06-3962.
Recurring chromosomal translocations observed in human leukemia often result in the expression of fusion proteins that are DNA-binding transcription factors. These altered proteins acquire new dimerization properties that result in the assembly of inappropriate multimeric transcription complexes that deregulate hematopoietic programs and induce leukemogenesis. Recently, we reported that the fusion protein AML1/MDS1/EVI1 (AME), a product of a t(3;21)(q26;q22) associated with chronic myelogenous leukemia and acute myelogenous leukemia, displays a complex pattern of self-interaction. Here, we show that the 8th zinc finger motif of MDS1/EVI1 is an oligomerization domain involved not only in interaction of AME with itself but also in interactions with the parental proteins, RUNX1 and MDS1/EVI1, from which AME is generated. Because the 8th zinc finger motif is also present in the oncoprotein EVI1, we have evaluated the effects of the interaction between RUNX1 and EVI1 in vitro and in vivo. We found that in vitro, this interaction alters the ability of RUNX1 to bind to DNA and to regulate a reporter gene, whereas in vivo, the expression of the isolated 8th zinc finger motif of EVI1 is sufficient to block the granulocyte colony-stimulating factor-induced differentiation of 32Dcl3 cells, leading to cell death. As EVI1 is not detected in normal bone marrow cells, these data suggest that its inappropriate expression could contribute to hematopoietic transformation in part by a new mechanism that involves EVI1 association with key hematopoietic regulators, leading to their functional impairment.
在人类白血病中观察到的复发性染色体易位常常导致融合蛋白的表达，这些融合蛋白是DNA结合转录因子。这些改变的蛋白获得了新的二聚化特性，导致形成不适当的多聚体转录复合物，从而使造血程序失调并诱导白血病发生。最近，我们报道了融合蛋白AML1/MDS1/EVI1（AME），它是与慢性粒细胞白血病和急性粒细胞白血病相关的t(3;21)(q26;q22)的产物，表现出复杂的自我相互作用模式。在这里，我们表明MDS1/EVI1的第8个锌指基序是一个寡聚化结构域，不仅参与AME自身的相互作用，还参与与产生AME的亲本蛋白RUNX1和MDS1/EVI1的相互作用。由于第8个锌指基序也存在于癌蛋白EVI1中，我们已经在体外和体内评估了RUNX1和EVI1之间相互作用的影响。我们发现，在体外，这种相互作用改变了RUNX1结合DNA和调节报告基因的能力，而在体内，EVI1分离的第8个锌指基序的表达足以阻断粒细胞集落刺激因子诱导的32Dcl3细胞分化，导致细胞死亡。由于在正常骨髓细胞中未检测到EVI1，这些数据表明其不适当的表达可能部分通过一种新机制导致造血转化，该机制涉及EVI1与关键造血调节因子的结合，导致它们的功能受损。
