ELL-associated factor 2 (EAF2), a functional homolog of EAF1 with alternative ELL binding properties
ELL-associated factor 2 (EAF2), a functional homolog of EAF1 with alternative ELL binding properties
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DOI：
10.1182/blood-2002-06-1664
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发表时间：
2003-03-15
期刊：
影响因子：
20.3
通讯作者：
Thirman, MJ
中科院分区：
文献类型：
--
作者：
Simone, F;Luo, RT;Thirman, MJ
急性白血病的(11；19)(q23；p13.1)易位导致MLL-ELL融合蛋白的形成。Ell是一种RNA聚合酶11延伸因子，与最近发现的EA 11蛋白相互作用。为了研究ELL的正常功能及其在融合到MILL时的异常活性，我们分离了与ELL相互作用的第二个蛋白EAF2，命名为ELL相关因子2。EAF2与EAF1高度同源，同源性为58%，氨基酸保守率为74%。利用产生的针对EAF2的特异性抗体，我们从多个细胞系中免疫共沉淀了ELL和EAF2。共聚焦显微镜显示内源性EAF2和ELL冷凝成核斑点状。与EAF2的数据库比对发现了一个与EAF1保守的富含丝氨酸、天冬氨酸和谷氨酸残基的区域，该区域与MILL的几个易位伙伴蛋白AF4和ENL具有氨基酸相似性。我们发现EAF2和EAF1在该区域都含有转录激活结构域。利用逆转录病毒骨髓转导技术，我们观察到EAF2与MLL的异种融合使造血祖细胞永生化。与EAF1不同，EAF2不与ELL的羧基末端结合。我们在ELL的氨基末端发现了一个与EAF1和EAF2结合的蛋白质-蛋白质相互作用结构域。这种氨基末端相互作用结构域在MLL-ELL融合蛋白的形成过程中被破坏。因此，MLL-ELL为EAF1保留了一个相互作用域，但为EAF2保留了HOT。综上所述，这些数据表明MLL-ELL可能扰乱ELL的正常蛋白质-蛋白质相互作用。
The (11;19)(q23;p13.1) translocation in acute leukemia results in the formation of an MLL-ELL fusion protein. ELL is an RNA polymerase 11 elongation factor that interacts with the recently identified EA 11 protein. To characterize the normal functions of ELL and its aberrant activities when fused to MILL, We isolated a second protein that interacts with ELL named EAF2 for ELL Associated Factor 2. EAF2 is highly homologous to EAF1, with 58% identity and 74% amino acid conservation. Using specific antibodies generated to EAF2, we coimmunoprecipitated ELL and EAF2 from multiple cell lines. Confocal microscopy revealed that endogenous EAF2 and ELL coldcalized in a nuclear speckled pattern. Database comparisons with EAF2 identified a region with a high content of serine, aspartic acid, and, glutamic, acid residues that is conserved with EAF1 and exhibited amino acid similarity with several translocation partner proteins of MILL, including AF4 and ENL. We found that EAF2 and EAF1 both contain transcriptional activation domains within this region. Using retroviral bone marrow transduction, we observed that a heterologous fusion of EAF2 to MLL immortalized hematopoietic progenitor cells. In contrast to EAF1, EAF2 does not bind to the carboxy-terminus of ELL. We identified a protein-protein interaction domain within the amino-terminus of ELL that binds to both EAF1 and EAF2. This amino-terminal interaction domain is disrupted in the formation of the MLL-ELL fusion protein. Thus, MLL-ELL retains an interaction domain for EAF1 but hot for EAF2. Taken together, these data suggest that MLL-ELL may disrupt the normal protein-protein interactions of ELL.