Pancreatic deletion of insulin receptor substrate 2 reduces beta and alpha cell mass and impairs glucose homeostasis in mice
Pancreatic deletion of insulin receptor substrate 2 reduces beta and alpha cell mass and impairs glucose homeostasis in mice
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DOI：
10.1007/s00125-007-0637-9
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发表时间：
2007-06-01
期刊：
影响因子：
8.2
通讯作者：
Withers, D. J.
中科院分区：
文献类型：
--
作者：
Cantley, J.;Choudhury, A. I.;Withers, D. J.
目的/假设胰岛素信号通路调节胰腺β细胞功能。使用Cre/loxP系统的条件性基因靶向已经证明，在β细胞中缺乏胰岛素受体底物2（IRS 2）的小鼠具有减少的β细胞质量。然而，当RIPCre（B6.Cg-tg（Ins 2-cre）25 Mgn/J）转基因小鼠（在大鼠胰岛素II启动子的控制下表达Cre重组酶）用于在胰岛素表达细胞中缺失floxed等位基因时，这些研究由于下丘脑缺失而变得复杂。这些特征导致显著的胰岛素抵抗，使得IRS 2的β细胞自主作用难以确定。为了建立删除Irs 2只在胰腺中的效果，我们产生PIrs 2KO小鼠，其中Cre重组酶表达由胰腺和十二指肠同源盒因子1（Pdx 1，也称为Ipf 1）基因的启动子驱动。材料和方法使用葡萄糖耐量和葡萄糖刺激的胰岛素分泌试验在PIrs 2KO小鼠中检查体内葡萄糖稳态。内分泌细胞质量通过形态计量学分析确定。在静态培养物中并通过在Fluo 3am负载的β细胞中进行钙成像来检查胰岛功能。结果PIrs 2KO小鼠在体内表现为葡萄糖耐受不良和葡萄糖刺激的胰岛素分泌障碍。胰腺胰岛素和胰高血糖素含量以及β和α细胞质量降低。葡萄糖刺激的胰岛素分泌和钙动员减弱PIrs 2KO胰岛。Glut 2基因（也称为Slc 2a 2）的表达也减少在PIrs 2KO mice.Conclusions/interpretation这些研究表明，IRS 2依赖的信号在胰岛不仅需要正常的β和α细胞质量的维护，但也参与了胰岛素分泌的调节。
Aims/hypothesis Insulin signalling pathways regulate pancreatic beta cell function. Conditional gene targeting using the Cre/loxP system has demonstrated that mice lacking insulin receptor substrate 2 (IRS2) in the beta cell have reduced beta cell mass. However, these studies have been complicated by hypothalamic deletion when the RIPCre (B6.Cg-tg(Ins2-cre)25Mgn/J) transgenic mouse (expressing Cre recombinase under the control of the rat insulin II promoter) is used to delete floxed alleles in insulin-expressing cells. These features have led to marked insulin resistance making the beta cell-autonomous role of IRS2 difficult to determine. To establish the effect of deleting Irs2 only in the pancreas, we generated PIrs2KO mice in which Cre recombinase expression was driven by the promoter of the pancreatic and duodenal homeobox factor 1 (Pdx1, also known as Ipf1) gene.Materials and methods In vivo glucose homeostasis was examined in PIrs2KO mice using glucose tolerance and glucose-stimulated insulin secretion tests. Endocrine cell mass was determined by morphometric analysis. Islet function was examined in static cultures and by performing calcium imaging in Fluo3am-loaded beta cells. Islet gene expression was determined by RT-PCR.Results The PIrs2KO mice displayed glucose intolerance and impaired glucose-stimulated insulin secretion in vivo. Pancreatic insulin and glucagon content and beta and alpha cell mass were reduced. Glucose-stimulated insulin secretion and calcium mobilisation were attenuated in PIrs2KO islets. Expression of the Glut2 gene (also known as Slc2a2) was also reduced in PIrs2KO mice.Conclusions/interpretation These studies suggest that IRS2-dependent signalling in pancreatic islets is required not only for the maintenance of normal beta and alpha cell mass but is also involved in the regulation of insulin secretion.