Joint regulation of the MAP1B promoter by HNF3β/Foxa2 and Engrailed is the result of a highly conserved mechanism for direct interaction of homeoproteins and Fox transcription factors
Joint regulation of the MAP1B promoter by HNF3β/Foxa2 and Engrailed is the result of a highly conserved mechanism for direct interaction of homeoproteins and Fox transcription factors
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DOI：
10.1242/dev.00414
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发表时间：
2003-05-01
期刊：
影响因子：
4.6
通讯作者：
Trembleau, A
中科院分区：
文献类型：
--
作者：
Foucher, I;Montesinos, ML;Trembleau, A
MAP1B(Map1b)启动子存在两个进化保守的重叠同源蛋白和肝细胞核因子3β(HNF3beta/Foxa2)同源结合位点(定义可能的同源蛋白/Fox位点，HF1和HF2)。相应地，含有HF1和HF2的启动子结构域可被含有Engraated和Foxa2的小脑核提取物识别，并在原代培养的胚胎中脑神经细胞中具有调节功能。转基因实验进一步证明，Engraated和Foxa2以剂量依赖的方式在生理上相互作用：FOXA2拮抗Engraded驱动的MAP1B启动子调控，反之亦然。这促使我们调查Engrailed和Foxa2是否直接相互作用。通过下拉实验证实了直接相互作用，并确定了参与这种相互作用的区域。在FOXA2中，相互作用的结构域是叉头盒DNA结合域。在Engrailed中，存在两个独立的相互作用结构域：同源结构域和包括PBX结合结构域的区域。最后，Foxa2不仅与Engraded结合，而且还与Lim1、GSC和Hoxa5同源蛋白结合，在这四种情况下，Foxa2至少与同源结构域结合。基于这两类蛋白质中的保守结构域的参与，我们认为叉头盒转录因子与同源蛋白之间的相互作用是一种普遍现象。
The MAP1B (Mtap1b) promoter presents two evolutionary conserved overlapping homeoproteins and Hepatocyte nuclear factor 3beta (HNF3beta/Foxa2) cognate binding sites (defining putative homeoprotein/Fox sites, HF1 and HF2). Accordingly, the promoter domain containing HF1 and HF2 is recognized by cerebellum nuclear extracts containing Engrailed and Foxa2 and has regulatory functions in primary cultures of embryonic mesmetencephalic nerve cells. Transfection experiments further demonstrate that Engrailed and Foxa2 interact physiologically in a dose-dependent manner: Foxa2 antagonizes the Engrailed-driven regulation of the MAP1B promoter, and vice versa. This led us to investigate if Engrailed and Foxa2 interact directly. Direct interaction was confirmed by pull-down experiments, and the regions participating in this interaction were identified. In Foxa2 the interacting domain is the Forkhead box DNA-binding domain. In Engrailed, two independent interacting domains exist: the homeodomain and a region that includes the Pbx-binding domain. Finally, Foxa2 not only binds Engrailed but also Lim1, Gsc and Hoxa5 homeoproteins and in the four cases Foxa2 binds at least the homeodomain. Based on the involvement of conserved domains in both classes of proteins, it is proposed that the interaction between Forkhead box transcription factors and homeoproteins is a general phenomenon.