Insulin-induced GLUT4 translocation to the plasma membrane is blunted in large compared with small primary fat cells isolated from the same individual
Insulin-induced GLUT4 translocation to the plasma membrane is blunted in large compared with small primary fat cells isolated from the same individual
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DOI：
10.1007/s00125-007-0713-1
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发表时间：
2007-08-01
期刊：
影响因子：
8.2
通讯作者：
Nystrom, F. H.
中科院分区：
文献类型：
--
作者：
Franck, N.;Stenkula, K. G.;Nystrom, F. H.
目的/假设几项研究表明，大脂肪细胞对胰岛素的反应比小脂肪细胞低。然而，在这些研究中，肥胖个体的大脂肪细胞与较瘦参与者的较小脂肪细胞进行了比较，实际上无法得出脂肪细胞大小与胰岛素敏感性之间是否存在因果关系的结论。我们假设，小的脂肪细胞可能是更多的胰岛素反应比大的脂肪细胞时，从同一individual.Materials和方法，我们开发了一种方法，通过使用两种不同的孔径大小的尼龙过滤器分离的原代人脂肪细胞。将细胞染色以使DNA可视化，这允许与诸如脂滴的伪影区分开。将分选的细胞放置过夜恢复，因为我们之前已经证明这对于正确评估胰岛素反应是必要的。结果当我们比较同一志愿者的小脂肪细胞和大脂肪细胞时，我们发现胰岛素受体（IR）、IRS-1和GLUT 4的含量相似。通过免疫印迹实验，使用来自两个细胞群的相同总细胞体积。胰岛素对IR、IRS-1和Akt 1（也称为蛋白激酶13）的激活在两个细胞群中相似。然而，免疫荧光共聚焦显微镜的质膜片没有发现任何增加的量GLUT 4在质膜胰岛素刺激后在大的脂肪细胞，而我们看到了两倍的量GLUT 4在小的脂肪cells.Conclusions/interpretation我们的研究结果支持肥胖个体的大脂肪细胞的积累和胰岛素反应性降低之间的因果关系。
Aims/hypothesis Several studies have suggested that large fat cells are less responsive to insulin than small fat cells. However, in these studies, large fat cells from obese individuals were compared with smaller fat cells from leaner participants, in effect making it impossible to draw conclusions about whether there is a causal relationship between fat cell size and insulin sensitivity. We hypothesised that small fat cells might be more insulin-responsive than large adipocytes when obtained from the same individual.Materials and methods We developed a method of sorting isolated primary human fat cells by using nylon filters of two different pore sizes. The cells were stained to visualise DNA, which allowed discrimination from artefacts such as lipid droplets. The sorted cells were left to recover overnight, since we had previously demonstrated that this is necessary for correct assessment of insulin response.Results We found similar amounts of the insulin receptor (IR), IRS-1 and GLUT4 when we compared small and large adipocytes from the same volunteer by immunoblotting experiments using the same total cell volume from both cell populations. Activation of IR, IRS-1 and Akt1 (also known as protein kinase 13) by insulin was similar in the two cell populations. However, immunofluorescence confocal microscopy of plasma membrane sheets did not reveal any increase in the amount of GLUT4 in the plasma membrane following insulin stimulation in the large fat cells, whereas we saw a twofold increase in the amount of GLUT4 in the small fat cells.Conclusions/interpretation Our results support a causal relationship between the accumulation of large fat cells in obese individuals and reduced insulin responsiveness.