Kim Ji-Won, Seghers Victor, Cho Jang-Hyeon, Kang Yup, Kim Soyeon, Ryu Yoonseok, Baek Kwanghee, Aguilar-Bryan Lydia, Lee Young-Don, Bryan Joseph, Suh-Kim Haeyoung
Department of Anatomy, Ajou University, School of Medicine, Suwon, 442-749, Korea.
Mol Endocrinol. 2002 May;16(5):1097-107. doi: 10.1210/mend.16.5.0934.
The sulfonylurea receptor 1 (SUR1) plays a key role in regulation of insulin secretion in pancreatic beta-cells. In this study we investigated the mechanism for tissue-specific expression of the SUR1 gene. A -138/-20 fragment exhibited basal promoter activity while the -660/-20 fragment contained a regulatory element for tissue-specific expression of the mouse SUR1 gene. A pancreatic beta-cell-specific transcription factor, BETA2 (beta-cell E box transcription factor)/NeuroD, enhanced the promoter activity of the -660/-20 fragment in cooperation with E47. Coexpression of a dominant negative mutant of BETA2/NeuroD, BETA2(1-233), repressed the promoter activity of the -660/-20 fragment. BETA2/NeuroD bound specifically to the E3 element located at -141. The E3 sequence in a heterologous context conferred transactivation by BETA2/NeuroD in HeLa and HIT cells. Mutation of E3 eliminated the stimulatory effect of BETA2/NeuroD. Unlike BETA2/NeuroD, neurogenin 3 (ngn3) could not activate the E3 element in HeLa cells. Overexpression of ngn3 concomitantly increased expression of BETA2/NeuroD and SUR1 in HIT cells but not in HeLa cells. These results indicate that BETA2/NeuroD induces tissue-specific expression of the SUR1 gene through the E3 element. These results also suggest that E3 is specific for BETA2/NeuroD, and the stimulatory effect of ngn3 in HIT cells may require factors specifically expressed in HIT cells.
磺脲类受体1（SUR1）在胰腺β细胞胰岛素分泌的调节中起关键作用。在本研究中，我们调查了SUR1基因组织特异性表达的机制。一个-138 / -20片段表现出基础启动子活性，而-660 / -20片段包含小鼠SUR1基因组织特异性表达的调控元件。胰腺β细胞特异性转录因子BETA2（β细胞E盒转录因子）/NeuroD与E47协同增强了-660 / -20片段的启动子活性。BETA2/NeuroD的显性负突变体BETA2(1-233)的共表达抑制了-660 / -20片段的启动子活性。BETA2/NeuroD特异性结合位于-141的E3元件。异源背景下的E3序列在HeLa和HIT细胞中赋予BETA2/NeuroD反式激活作用。E3的突变消除了BETA2/NeuroD的刺激作用。与BETA2/NeuroD不同，神经发生素3（ngn3）不能激活HeLa细胞中的E3元件。ngn3的过表达在HIT细胞中同时增加了BETA2/NeuroD和SUR1的表达，但在HeLa细胞中没有增加。这些结果表明，BETA2/NeuroD通过E3元件诱导SUR1基因的组织特异性表达。这些结果还表明，E3对BETA2/NeuroD具有特异性，ngn3在HIT细胞中的刺激作用可能需要HIT细胞中特异性表达的因子。
