Cooperative DNA binding with AP-1 proteins is required for transformation by EWS-Ets fusion proteins
Cooperative DNA binding with AP-1 proteins is required for transformation by EWS-Ets fusion proteins
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DOI：
10.1128/mcb.26.7.2467-2478.2006
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发表时间：
2006-04-01
影响因子：
5.3
通讯作者：
Wisdom, R
中科院分区：
文献类型：
--
作者：
Kim, S;Denny, CT;Wisdom, R
尤文氏肉瘤发生的一个关键分子事件是染色体易位的持续存在，这些易位导致EWS的氨基末端与包括DNA结合域在内的五种不同ETS家族蛋白之一的羧基末端融合。这些融合蛋白作为非调控转录因子发挥作用，导致基因表达的异常控制。最近的数据表明，一些EWS-ETS靶向启动子，包括尿苷磷酸化酶(UPP)启动子，含有ETS和AP-1蛋白的串联结合位点。在这里，我们发现那些参与尤文氏肉瘤的ETS家族蛋白，包括FLI1，ERG和ETV1，协同结合这些串联元件与Fos-Jun，而其他ETS家族成员不这样做。体外对这种协同性的分析表明：(I)Ets和AP-1位点的许多不同空间排列支持协同结合，(Ii)Fos和Jun的bZIP基序足以支持这种协同结合，以及(Iii)FLI1的Ets结构域和羧基末端序列对于协同DNA结合都是重要的。EWS-FLI1激活UPP mRNA的表达，直接与UPP启动子结合，并转化3T3成纤维细胞；相比之下，C端截断的EWS-FLI1突变形式不能与DNA协同结合Fos-Jun，在所有这些特性中都是缺陷的。结果表明，EWS-ETS蛋白协同结合DNA和Fos-Jun的能力是这些蛋白生物学活性的关键。这一结果对了解尤文肉瘤的发病机制具有重要意义。此外，它们可能与含有串联Ets和AP-1结合位点的基因的RAS依赖激活机制有关。
A key molecular event in the genesis of Ewing's sarcoma is the consistent presence of chromosomal translocations that result in the formation of proteins in which the amino terminus of EWS is fused to the carboxyl terminus, including the DNA binding domain, of one of five different Ets family proteins. These fusion proteins function as deregulated transcription factors, resulting in aberrant control of gene expression. Recent data indicate that some EWS-Ets target promoters, including the uridine phosphorylase (UPP) promoter, harbor tandem binding sites for Ets and AP-1 proteins. Here we show that those Ets family proteins that participate in Ewing's sarcoma, including Fli1, ERG, and ETV1, cooperatively bind these tandem elements with Fos-Jun while other Ets family members do not. Analysis of this cooperativity in vitro shows that (i) many different spatial arrangements of the Ets and AP-1 sites support cooperative binding, (ii) the bZIP motifs of Fos and Jun are sufficient to support this cooperativity, and (iii) both the Ets domain and carboxy-terminal sequences of Fli1 are important for cooperative DNA binding. EWS-Fli1 activates the expression of UPP mRNA, is directly bound to the UPP promoter, and transforms 3T3 fibroblasts; in contrast, a C-terminally truncated mutant form of EWS-Fli1 that cannot cooperatively bind DNA with Fos-Jun is defective in all of these properties. The results show that the ability of EWS-Ets proteins to cooperatively bind DNA with Fos-Jun is critical to the biologic activities of these proteins. The results have implications for understanding the pathogenesis of Ewing's sarcoma. In addition, they may be relevant to the mechanisms of Ras-dependent activation of genes that harbor tandem Ets and AP-1 binding sites.