Molecular Mechanisms for Pancreatic Islet Disfunction in Development of Diabetes Mellitus-a study using WFS1 knockout mice

糖尿病发生过程中胰岛功能障碍的分子机制——WFS1基因敲除小鼠的研究

基本信息

批准号：
17590264
负责人：
ISHIHARA Hisamitsu
金额：
$ 2.24万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

Establishment of WFS1-deficient insulinoma cell lines. To examine the influence of WFS1-deficiency specifically in a homogenous β-cell population, β-cell lines were established by crossing wfs1^<-/-> mice with IT6 mice expressing simian virus 40 large T antigen under the insulin promoter. We found impaired insulin secretion in response to high glucose, which was recovered by adenovirus-mediated expression of wild-type WFS 1 but not of mutant WFS1 proteins found in Wolfram-syndrome patients.Role of WFS1 protein in intracellular calcium homeostasis. We analyzed WFS1-knockdown and-overexpressing HEK293 cells, and found that WFS1 protein modulates [Ca^<2+>]_<er> by positively regulating the ER Ca^<2+> uptake, which is associated with changes in the [Ca^<2+>]_<cyt> response evoked by Ca^<2+> store depletion.Identification of the translational suppressor 4E-BP1 as a pro-survival factor in β-cells under ER stress. Expression profiling in WFS1-deficient islets revealed increased 4E-BPI expression. We found that expression of 4E-BP1 was also enhanced in islets under ER stress in mouse models of diabetes. 4E-BP1 induction was found to be mediated by the transcription factor ATF4. 4E-BP1-deficient MIN6 β-cells were more vulnerable to apoptosis triggered by ER stress, with greater induction of C/EBP homologue protein. Furthermore, Eif4ebp1 deletion exacerbated hyperglycemia, with accelerated (3-cell failure, in mouse diabetes models with ER stress. Thus, 4E-BP1 induction is a pro-survival signal for (3-cells under ER stress and a potential therapeutic target for diabetes.Increased glucagon secretion from WFS1-deficient islets. Pyruvate was previously shown to stimulate glucagon secretion. In this study, we found increased alpha cell numbers and enhanced pyruvate-stimulated glucagon secretion in WFS1-deficient islets.Multiple abnormalities are suggested to contribute development of diabetes in the mouse model of Wolfram syndrome.

WFS1 缺陷型胰岛素瘤细胞系的建立为了检查 WFS1 缺陷对同质 β 细胞群的影响，通过将 wfs1^<-/-> 小鼠与表达猿病毒 40 Large 的 IT6 小鼠杂交来建立 β 细胞系。我们发现胰岛素启动子下的 T 抗原对高葡萄糖的反应受损，这种情况可以通过腺病毒介导的野生型 WFS 1 表达来恢复，但不能通过在体内发现的突变型 WFS1 蛋白来恢复。 Wolfram 综合征患者。WFS1 蛋白在细胞内钙稳态中的作用我们分析了 WFS1 敲低和过表达的 HEK293 细胞，发现 WFS1 蛋白通过正向调节 ER Ca^ 来调节 [Ca^<2+>]_<er>。 <2+> 摄取，与 Ca^<2+> 存储引起的 [Ca^<2+>]_<cyt> 反应的变化相关鉴定翻译抑制因子 4E-BP1 作为 ER 应激下 β 细胞的促存活因子。在 WFS1 缺陷的胰岛中的表达谱显示 4E-BPI 表达增加。我们发现 4E-BP1 的表达也增强。研究发现，糖尿病小鼠模型中的 ER 应激是由转录因子 ATF4 介导的。 MIN6 β 细胞更容易受到 ER 应激引发的细胞凋亡，C/EBP 同源蛋白的诱导作用更强。此外，Eif4ebp1 缺失会加剧高血糖，在具有 ER 应激的小鼠糖尿病模型中加速（3 细胞衰竭）。因此，4E。 -BP1 诱导是 ER 应激下的 (3-细胞) 的促生存信号，也是糖尿病的潜在治疗靶标。WFS1 缺陷的胰岛的胰高血糖素分泌增加。丙酮酸先前被证明可以刺激胰高血糖素分泌。在这项研究中，我们发现 WFS1 缺陷的胰岛中的α细胞数量增加，丙酮酸刺激的胰高血糖素分泌增强。在 Wolfram 综合征小鼠模型中，多种异常被认为有助于糖尿病的发生。