Regulation of ATP-sensitive potassium channel subunit Kir6.2 expression in rat intestinal insulin-producing progenitor cells
Regulation of ATP-sensitive potassium channel subunit Kir6.2 expression in rat intestinal insulin-producing progenitor cells
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DOI：
10.1074/jbc.m410759200
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发表时间：
2005-01-21
影响因子：
4.8
通讯作者：
Kashiwagi, A
中科院分区：
文献类型：
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作者：
Hashimoto, T;Nakamura, T;Kashiwagi, A
我们已经报道了Pdx-1（胰腺十二指肠同源框1）和Isl-1（胰岛1）的联合表达使未成熟的大鼠肠上皮细胞（IEC-6）产生和释放胰岛素。调节胰岛素释放的关键组分是ATP敏感性钾通道亚基Kir6.2。为了研究Kir6.2基因表达的调节，我们评估了表达Pdx-1和/或Isl-1的IEC-6细胞中Kir6.2的表达。我们观察到Kir6.2蛋白在同时表达Pdx-1和Isl-1的IEC-6细胞中重新表达，但在单独表达Pdx-1的细胞中不表达。接下来，我们通过荧光素酶测定和电泳迁移率变动测定分析了Kir6.2启动子区域（-1677/-45）。结果表明，Kir6.2启动子具有两个调控启动子活性的区域：Foxa 2结合位点（-1364 ~-1210）和Sp1/Sp3结合位点（-1035 ~-939）。在表达Pdx-1的IEC-6细胞中Isl-1的额外表达减弱了Foxa 2蛋白的过表达并增强了Kir6.2的表达。最后，使用iRNA技术敲低Isl-1导致大鼠胰腺β细胞系（RIN-5 F细胞）中Kir6.2蛋白的表达降低。这些结果表明，Kir6.2在大鼠肠中的表达受Isl-1调节。
We have reported that the combined expression of Pdx-1 (pancreatic duodenal homeobox 1) and Isl-1 (islet 1) enables immature rat enterocytes (IEC-6) to produce and release insulin. A key component regulating the release of insulin is the ATP-sensitive potassium channel subunit Kir6.2. To investigate the regulation of Kir6.2 gene expression, we assessed Kir6.2 expression in IEC-6 cells expressing Pdx-1 and/or Isl-1. We observed that Kir6.2 protein was expressed de novo in IEC-6 cells expressing both Pdx-1 and Isl-1 but not in cells expressing Pdx-1 alone. Next, we analyzed the regions of the Kir6.2 promoter (-1677/-45) by performing a luciferase assay and electrophoretic mobility shift assay. The results have demonstrated that Kir6.2 promoter possesses two regions regulating the promoter activity: a Foxa2-binding site (-1364 to -1210) and an Sp1/Sp3-binding site (-1035 to -939). The additional expression of Isl-1 in IEC-6 cells expressing Pdx-1 attenuated overexpression of Foxa2 protein and enhanced Kir6.2 expression. Finally, knockdown of Isl-1 using the iRNA technique resulted in decreased expression of Kir6.2 protein in a rat pancreatic beta-cell line (RIN-5F cells). These results indicate that expression of Kir6.2 in the rat intestine is moderated by Isl-1.