Insulin Stimulates Translocation of Human GLUT4 to the Membrane in Fat Bodies of Transgenic Drosophila melanogaster
Insulin Stimulates Translocation of Human GLUT4 to the Membrane in Fat Bodies of Transgenic Drosophila melanogaster
复制标题
DOI：
10.1371/journal.pone.0077953
复制
发表时间：
2013-11-06
期刊：
影响因子：
3.7
通讯作者：
Pick, Leslie
中科院分区：
文献类型：
--
作者：
Crivat, Georgeta;Lizunov, Vladimir A.;Pick, Leslie
果蝇黑腹果蝇是研究控制发育和疾病的基因的优秀模型系统。然而，由于昆虫和哺乳动物之间的代谢差异，其对生理系统的适用性不太清楚。由于胰岛素信号与糖尿病和其他疾病的相关性，已经在哺乳动物中进行了研究，但哺乳动物和昆虫之间的途径有许多相似之处。例如，果蝇胰岛素样肽的缺失导致“糖尿病”果蝇循环糖水平升高。这种情况是否反映了在哺乳动物中观察到的糖摄取到外周组织中的失败尚不清楚，这取决于苍蝇是否具有安装类胰岛素依赖性糖摄取反应的机制。在这里，我们问果蝇脂肪细胞是否有能力响应胰岛素与糖转运蛋白的调节贩运。产生了表达人葡萄糖转运蛋白4（GLUT 4）的转基因果蝇，该糖转运蛋白主要在胰岛素应答组织中表达。在脂肪体中表达后，通过共聚焦和全内反射荧光显微镜（TIRFM）监测GLUT4细胞内运输和定位。我们发现，脂肪体细胞对胰岛素的反应是增加GLUT4的运输和转运到质膜。虽然这些反应的幅度在标准饮食饲养的动物中相对较弱，但在限糖饮食饲养的动物中大大增强，这表明喂食标准饮食的苍蝇具有胰岛素抵抗性。我们的研究结果表明，苍蝇能够响应胰岛素而动员糖转运蛋白转移到细胞表面。他们认为，果蝇脂肪细胞对胰岛素有反应，当动物暴露于恒定的高水平糖时，这些途径被下调。最后，这些研究是第一次使用TIRFM监测果蝇中的胰岛素信号通路，证明了TIRFM的标签糖转运蛋白监测昆虫中的信号通路的实用性。
The fruit fly Drosophila melanogaster is an excellent model system for studies of genes controlling development and disease. However, its applicability to physiological systems is less clear because of metabolic differences between insects and mammals. Insulin signaling has been studied in mammals because of relevance to diabetes and other diseases but there are many parallels between mammalian and insect pathways. For example, deletion of Drosophila Insulin-Like Peptides resulted in 'diabetic' flies with elevated circulating sugar levels. Whether this situation reflects failure of sugar uptake into peripheral tissues as seen in mammals is unclear and depends upon whether flies harbor the machinery to mount mammalian-like insulin-dependent sugar uptake responses. Here we asked whether Drosophila fat cells are competent to respond to insulin with mammalian-like regulated trafficking of sugar transporters. Transgenic Drosophila expressing human glucose transporter-4 (GLUT4), the sugar transporter expressed primarily in insulin-responsive tissues, were generated. After expression in fat bodies, GLUT4 intracellular trafficking and localization were monitored by confocal and total internal reflection fluorescence microscopy (TIRFM). We found that fat body cells responded to insulin with increased GLUT4 trafficking and translocation to the plasma membrane. While the amplitude of these responses was relatively weak in animals reared on a standard diet, it was greatly enhanced in animals reared on sugar-restricted diets, suggesting that flies fed standard diets are insulin resistant. Our findings demonstrate that flies are competent to mobilize translocation of sugar transporters to the cell surface in response to insulin. They suggest that Drosophila fat cells are primed for a response to insulin and that these pathways are down-regulated when animals are exposed to constant, high levels of sugar. Finally, these studies are the first to use TIRFM to monitor insulin-signaling pathways in Drosophila, demonstrating the utility of TIRFM of tagged sugar transporters to monitor signaling pathways in insects.