The endoplasmic reticulum stress response is stimulated through the continuous activation of transcription factors ATF6 and XBP1 in Ins2+/Akita pancreatic β cells
The endoplasmic reticulum stress response is stimulated through the continuous activation of transcription factors ATF6 and XBP1 in Ins2+/Akita pancreatic β cells
复制标题
DOI：
10.1111/j.1356-9597.2004.00721.x
复制
发表时间：
2004-03-01
期刊：
影响因子：
2.1
通讯作者：
Nagata, K
中科院分区：
文献类型：
--
作者：
Nozaki, J;Kubota, H;Nagata, K
两种鼠胰岛素基因之一Ins 2的显性C96 Y突变导致“秋田”小鼠糖尿病。在此，我们从杂合小鼠（Ins 2（+/秋田））建立了胰岛β细胞系。内质网（ER）分子伴侣蛋白的Western blot分析表明，与野生型（Ins 2（+/+））细胞相比，Ins 2（+/秋田）细胞中Grp 78、Grp 94和Orp 150的表达显著增加。使用人GRP 78启动子与或不与ER应激反应元件（ERSE）的报告基因测定显示Ins 2（+/秋田）细胞比Ins 2（+/+）细胞表现出显著更强的ERSE依赖的转录活性。在野生型β细胞中Ins 2 C96 Y突变体的瞬时过表达比野生型Ins 2过表达诱导更强的ERSE依赖性应激反应。ERSE结合转录因子ATF 6在Ins 2（+/秋田）细胞中被强烈激活。含有另一种ERSE结合转录因子XBP 1的特异性结合序列的报告基因的活性在Ins 2（+/秋田）细胞中也得到增强。在Ins 2（+/秋田）细胞中，活性形式的XBP 1 mRNA和蛋白水平均显著升高。这些结果表明，该细胞系受到持续的ER应激，Ins 2 C96 Y突变通过激活ATF 6和XBP 1诱导ER伴侣蛋白的表达。
The dominant C96Y mutation of one of the two murine insulin genes, Ins2, causes diabetes mellitus in 'Akita' mice. Here we established pancreatic islet beta cell lines from heterozygous mice (Ins2(+/Akita)). Western blot analysis of endoplasmic reticulum (ER) molecular chaperones indicated that Grp78, Grp94 and Orp150 are significantly increased in Ins2(+/Akita) cells compared with wild-type (Ins2(+/+)) cells. Reporter gene assays using the human GRP78 promoter with or without the ER stress response element (ERSE) showed that Ins2(+/Akita) cells exhibit significantly stronger ERSE-dependent transcriptional activity than Ins2(+/+) cells. Transient over-expression of the Ins2 C96Y mutant in wild-type beta cells induces a stronger ERSE-dependent stress response than does wild-type Ins2 over-expression. The ERSE-binding transcription factor ATF6 is strongly activated in Ins2(+/Akita) cells. The activity of a reporter containing the specific binding sequence of another ERSE-binding transcription factor, XBP1, is also enhanced in Ins2(+/Akita) cells. Levels of active forms of XBP1 mRNA and protein are both markedly elevated in Ins2(+/Akita) cells. These results indicate that this cell line is subject to continuous ER stress and that the Ins2 C96Y mutation induces the expression of ER chaperones through the activation of ATF6 and XBP1.