NFAT regulates insulin gene promoter activity in response to synergistic pathways induced by glucose and glucagon-like peptide-1
NFAT regulates insulin gene promoter activity in response to synergistic pathways induced by glucose and glucagon-like peptide-1
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DOI：
10.2337/diabetes.51.3.691
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发表时间：
2002-03-01
期刊：
影响因子：
7.7
通讯作者：
Easom, RA
中科院分区：
文献类型：
--
作者：
Lawrence, MC;Bhatt, HS;Easom, RA
目前，人们对胰高血糖素样肽 1 (GLP-1) 调节 β 细胞功能（包括胰岛素基因转录）的作用机制产生了浓厚的兴趣。在这项研究中，GLP-1（100 nmol/l）在葡萄糖（11 mmol/l）存在下，诱导 INS-1 胰腺 β 细胞中胰岛素基因启动子活性增加了 71 倍，这一效应比单独使用任何一种兴奋剂都要大一个数量级。对 GLP-1 的反应与毛喉素相似，并且很大程度上受到蛋白激酶 A (PICA) 抑制剂 H89 和肉豆蔻酰化 PKI(14-22) 酰胺的抑制，表明通过 cAMP/PKA 途径进行部分介导。值得注意的是，选择性 Ca2+/钙调蛋白依赖性磷酸酶 2B（钙调神经磷酸酶）抑制剂 FK506 以及 BAPTA（双（2-氨基苯氧基）乙烷-N,N,N',N'-四乙酸酯）对细胞内 Ca2+ 的螯合作用均消除了 GLP-1 和毛喉素的作用。葡萄糖和 GLP-1 还协同激活 NFAT（激活 T 细胞的核因子）介导的转录，该转录来自包含串联 NFAT 共有序列的最小启动子构建体。此外，大鼠胰岛素 I 启动子内三个已识别的 NFAT 位点中任何一个的两点碱基对突变都会导致葡萄糖和 GLP-1 的联合作用显着降低。这些数据表明，葡萄糖和 GLP-1 促进胰岛素基因转录的协同作用是通过胰腺 β 细胞中 PKA 和钙调磷酸酶依赖性途径通过 NFAT 介导的。
Currently there is intense interest to define the mechanism of action of glucagon-like peptide-1 (GLP-1) in regulating beta-cell function, including insulin gene transcription. In this study, GLP-1 (100 nmol/l), in the presence of glucose (11 mmol/l), induced a similar to71-fold increase in insulin gene promoter activity in INS-1 pancreatic beta-cells, an effect that was an order of magnitude larger than with either stimulant alone. The response to GLP-1 was mimicked by forskolin and largely inhibited by the protein kinase A (PICA) inhibitors, H89 and myristoylated PKI(14-22) amide, indicating partial mediation via a cAMP/PKA pathway. Significantly, the actions of both GLP-1 and forskolin were abolished by the selective Ca2+/calmodulin-dependent phosphatase 2B (calcineurin) inhibitor, FK506, as well as by the chelation of intracellular Ca2+ by BAPTA (bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetate). Glucose and GLP-1 also synergistically activated NFAT (nuclear factor of activated T-cells)-mediated transcription from a minimal promoter construct containing tandem NFAT consensus sequences. Furthermore, two-point base pair mutations in any of the three identified NFAT sites within the rat insulin I promoter resulted in a significant reduction in the combined effect of glucose and GLP-1. These data suggest that the synergistic action of glucose and GLP-1 to promote insulin gene transcription is mediated through NFAT via PKA- and calcineurin-dependent pathways in pancreatic beta-cells.