Functional cloning of TUG as a regulator of GLUT4 glucose transporter trafficking
Functional cloning of TUG as a regulator of GLUT4 glucose transporter trafficking
复制标题
DOI：
10.1038/nature01989
复制
发表时间：
2003-10-16
期刊：
影响因子：
64.8
通讯作者：
Lodish, HF
中科院分区：
文献类型：
--
作者：
Bogan, JS;Hendon, N;Lodish, HF
胰岛素通过动员GLUT 4葡萄糖转运蛋白刺激脂肪和肌肉中的葡萄糖摄取。GLUT 4在不存在胰岛素的情况下被隔离在细胞内，并在胰岛素刺激的几分钟内重新分布到质膜（1，2）。但是控制GLUT 4螯合的贩运机制仍然难以捉摸。在这里，我们描述了一个功能筛选，以确定蛋白质，调节GLUT 4的分布，并确定TUG作为一个假定的系链，包含一个UBX域，GLUT 4。在截短形式中，TUG以显性负性方式抑制胰岛素刺激的GLUT 4在中国仓鼠卵巢细胞和3 T3-L1脂肪细胞中的再分布。全长TUG与GLUT 4特异性形成复合物;在3 T3-L1脂肪细胞中，该复合物存在于未刺激的细胞中，并在很大程度上被胰岛素分解。内源性TUG定位于未刺激的3 T3-L1脂肪细胞中的GLUT 4的胰岛素可动员池，并且不被胰岛素动员到质膜。TUG的不同区域需要结合GLUT 4并将GLUT 4保留在转染的非脂肪细胞中的细胞内。我们的数据表明，TUG陷阱内吞的GLUT 4和系绳细胞内，胰岛素动员这个池保留GLUT 4通过释放这个系绳。
Insulin stimulates glucose uptake in fat and muscle by mobilizing the GLUT4 glucose transporter. GLUT4 is sequestered intracellularly in the absence of insulin, and is redistributed to the plasma membrane within minutes of insulin stimulation(1,2). But the trafficking mechanisms that control GLUT4 sequestration have remained elusive. Here we describe a functional screen to identify proteins that modulate GLUT4 distribution, and identify TUG as a putative tether, containing a UBX domain, for GLUT4. In truncated form, TUG acts in a dominant-negative manner to inhibit insulin-stimulated GLUT4 redistribution in Chinese hamster ovary cells and 3T3-L1 adipocytes. Full-length TUG forms a complex specifically with GLUT4; in 3T3-L1 adipocytes, this complex is present in unstimulated cells and is largely disassembled by insulin. Endogenous TUG is localized with the insulin-mobilizable pool of GLUT4 in unstimulated 3T3-L1 adipocytes, and is not mobilized to the plasma membrane by insulin. Distinct regions of TUG are required to bind GLUT4 and to retain GLUT4 intracellularly in transfected, non-adipose cells. Our data suggest that TUG traps endocytosed GLUT4 and tethers it intracellularly, and that insulin mobilizes this pool of retained GLUT4 by releasing this tether.