Isolation and characterization of a novel transcription factor that binds to and activates insulin control element-mediated expression.
Isolation and characterization of a novel transcription factor that binds to and activates insulin control element-mediated expression.
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一种新型转录因子的分离和表征，该转录因子结合并激活胰岛素控制元件介导的表达。
DOI：
10.1128/mcb.14.10.6704-6714.1994
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发表时间：
1994
影响因子：
5.3
通讯作者：
Stein,R
中科院分区：
文献类型：
--
作者：
Robinson,GL;Cordle,SR;Henderson,E;Weil,PA;Teitelman,G;Stein,R
胰岛素基因的胰腺β细胞类型特异性转录主要由单个顺式作用DNA序列元件（称为胰岛素控制元件（ICE））调节，该元件位于该基因的5′侧翼区。ICE激活剂是一种异聚体复合物，由与广泛分布的E2 A编码蛋白（E12、E47和E2-5）相关的胰岛α/β细胞特异性因子组成。我们描述了存在于α和β细胞中的蛋白质的cDNA的分离和表征，称为胰岛素激活因子的INSAF，其结合并激活ICE介导的表达。从人胰岛素瘤cDNA文库中分离INSAF。转染实验表明，INSAF激活ICE在胰岛素表达细胞中的表达，但在非胰岛素表达细胞中没有。共转染实验表明，激活INSAF抑制Id，碱性螺旋-环-螺旋（bHLH）蛋白功能的负调节剂。INSAF还显示在体外与bHLH蛋白E12相关。此外，亲和纯化的INSAF抗血清废除了激活剂特异性ICE结合复合物的形成。免疫组织化学研究表明，INSAF在其表达模式方面受到限制，因为INSAF似乎仅在胰岛胰腺α和β细胞的细胞核内检测到。所有这些数据都与INSAF是ICE激活剂的一部分或与胰岛素基因转录所需的特异性激活剂抗原相关的提议一致。
Pancreatic β-cell-type-specific transcription of the insulin gene is principally regulated by a single cis-acting DNA sequence element, termed the insulin control element (ICE), which is found within the 5′-flanking region of the gene. The ICE activator is a heteromeric complex composed of an islet α/β-cell-specific factor associated with the ubiquitously distributed E2A-encoded proteins (E12, E47, and E2-5). We describe the isolation and characterization of a cDNA for a protein present in α and β cells, termed INSAF for insulin activator factor, which binds to and activates ICE-mediated expression. INSAF was isolated from a human insulinoma cDNA library. Transfection experiments demonstrated that INSAF activates ICE expression in insulin-expressing cells but not in non-insulin-expressing cells. Cotransfection experiments showed that activation by INSAF was inhibited by Id, a negative regulator of basic helix-loop-helix (bHLH) protein function. INSAF was also shown to associate in vitro with the bHLH protein E12. In addition, affinity-purified INSAF antiserum abolished the formation of the activator-specific ICE-binding complex. Immunohistochemical studies indicate that INSAF is restricted in terms of its expression pattern, in that INSAF appears to be detected only within the nuclei of islet pancreatic α and β cells. All of these data are consistent with the proposal that INSAF is either part of the ICE activator or is antigenically related to the specific activator required for insulin gene transcription.