Cooperative interaction between ETS1 and GFI1 transcription factors in the repression of Bax gene expression
Cooperative interaction between ETS1 and GFI1 transcription factors in the repression of Bax gene expression
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DOI：
10.1038/sj.onc.1210140
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发表时间：
2007-05-01
期刊：
影响因子：
8
通讯作者：
Oikawa, T.
中科院分区：
文献类型：
--
作者：
Nakazawa, Y.;Suzuki, M.;Oikawa, T.
原癌蛋白ETS1和生长因子独立-1 （growth factor independent-1, GFI1）参与各种类型细胞的生长和分化，其不受调控的表达参与了恶性转化。在这里，我们报道了ETS1和GFI1通过它们的串扰相互作用并影响基因表达。共免疫沉淀分析和谷胱甘肽- s -转移酶下拉试验表明，ETS1通过其Ets结构域直接与GFI1结合，GFI1通过其锌指结构域与ETS1结合。荧光素酶（Luc）测定显示，GFI1抑制ETS1介导的转录激活，ETS1抑制GFI1介导的转录激活，且呈剂量依赖性。然而，在Ets和gfi结合位点（EBS和GBS）相邻的Bax启动子中，ETS1和GFI1共同降低了激活。对Bax启动子的EBS和GBS进行定点突变表明，这两个结合位点都是完全抑制所必需的。染色质免疫沉淀分析证实，即使EBS或GBS发生突变，在Bax启动子上也会形成ETS1-GFI1复合物。引入针对ETS1和/或GFI1的小干扰RNA可增强内源性Bax基因的表达。我们的研究结果表明，ETS1和GFI1之间的相互作用促进了它们与特异性的结合。在体内抑制Bax启动子上的c位点的表达。
The proto-oncoproteins ETS1 and growth factor independent-1 (GFI1) are implicated in cell growth and differentiation in various types of cells, and their deregulated expression is involved in malignant transformation. Here, we report that ETS1 and GFI1 interact and affect gene expression through their cross-talk. Co-immunoprecipitation analyses and glutathione-S-transferase pull-down assays revealed that ETS1 bound directly to GFI1 via its Ets domain, and GFI1 bound to ETS1 via its zinc-finger domain. Luciferase (Luc) assays using artificial reporters showed that GFI1 repressed ETS1-mediated transcriptional activation and ETS1 repressed GFI1-mediated transcriptional activation, in a dose-dependent manner. However, in the Bax promoter where the Ets- and Gfi-binding sites (EBS and GBS) are adjacent, ETS1 and GFI1 cooperatively reduced activation. Site-directed mutagenesis on the EBS and GBS of the Bax promoter showed that both binding sites were necessary for full repression. Chromatin immunoprecipitation analyses con. rmed that an ETS1-GFI1 complex formed on the Bax promoter even when either EBS or GBS was mutated. Introduction of small interfering RNA against ETS1 and/ or GFI1 enhanced endogenous Bax gene expression. Our results suggest that the interaction between ETS1 and GFI1 facilitates their binding to speci. c sites on the Bax promoter and represses Bax expression in vivo.