ATF-2 stimulates the human insulin promoter through the conserved CRE2 sequence
ATF-2 stimulates the human insulin promoter through the conserved CRE2 sequence
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DOI：
10.1016/j.bbaexp.2007.01.005
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发表时间：
2007-02-01
期刊：
影响因子：
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通讯作者：
Docherty, Kevin
中科院分区：
文献类型：
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作者：
Hay, Colin W.;Ferguson, Laura A.;Docherty, Kevin
胰岛素启动子包含许多不同的顺式作用调控元件，这些元件结合一系列组织特异性和普遍存在的转录因子。在胰岛素启动子内的调控元件中，环AMP响应元件（CRE）结合了迄今为止最多样化的转录因子。啮齿动物胰岛素启动子只有一个CRE位点，而人类胰岛素基因中有四个CRE位点，其中CRE2是唯一一个在物种间保守的CRE位点。本研究的目的是表征人类CRE2位点，并调查两种主要的CRE2相关转录因子的影响；CREB-1和ATF-2。将含有人胰岛素基因启动子的启动子构建体置于萤火虫荧光素酶报告基因的上游，并将ATF-2或CREB-1的表达质粒共同转染INS-1胰腺β细胞，结果表明，ATF-2刺激了转录活性，而CREB-1则引起了抑制作用。突变CRE2会减弱ATF-2的作用，而CREB-1则不会。电泳迁移迁移试验和染色质免疫沉淀显示ATF-2与CRE2位点结合，而siRNA介导的ATF-2敲低会减弱cAMP相关信号传导对启动子活性的刺激作用。这些结果表明，ATF-2可能是人类胰岛素启动子的关键调节因子，可能在响应细胞外信号时刺激活性。(c) 2007 Elsevier B.V.版权所有
The insulin promoter contains a number of dissimilar cis-acting regulatory elements that bind a range of tissue specific and ubiquitous transcription factors. Of the regulatory elements within the insulin promoter, the cyclic AMP responsive element (CRE) binds by far the most diverse array of transcription factors. Rodent insulin promoters have a single CRE site, whereas there are four CREs within the human insulin gene, of which CRE2 is the only one conserved between species. The aim of this study was to characterise the human CRE2 site and to investigate the effects of the two principal CRE-associated transcription factors; CREB-1 and ATF-2. Co-transfection of INS-1 pancreatic beta-cells with promoter constructs containing the human insulin gene promoter placed upstream of the firefly luciferase reporter gene and expression plasmids for ATF-2 or CREB-1 showed that ATF-2 stimulated transcriptional activity while CREB-1 elicited an inhibitory effect. Mutagenesis of CRE2 diminished the effect of ATF-2 but not that of CREB-1. ATF-2 was shown to bind to the CRE2 site by electrophoretic mobility shift assay and by chromatin immunoprecipitation, while siRNA mediated knockdown of ATF-2 diminished the stimulatory effects of cAMP related signalling on promoter activity. These results suggest that ATF-2 may be a key regulator of the human insulin promoter possibly stimulating activity in response to extracellular signals. (c) 2007 Elsevier B.V. All rights reserved.