Cellular mechanism of the insulin-like effect of growth hormone in adipocytes. Rapid translocation of the HepG2-type and adipocyte/muscle glucose transporters.
Cellular mechanism of the insulin-like effect of growth hormone in adipocytes. Rapid translocation of the HepG2-type and adipocyte/muscle glucose transporters.
复制标题
脂肪细胞中生长激素的类胰岛素作用的细胞机制。
DOI：
10.1042/bj2820099
复制
发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Glenn,KC
中科院分区：
文献类型：
--
作者：
Tanner,JW;Leingang,KA;Mueckler,MM;Glenn,KC
在体外分化的原代大鼠脂肪细胞培养中，研究了生长激素(GH)刺激脂肪细胞摄取葡萄糖的细胞机制。用胶原酶消化幼年大鼠腹股沟脂肪垫分离前脂肪细胞，并在3-异丁基-1-甲基黄嘌呤、胰岛素和地塞米松存在下进行分化。分化开始后6天以上观察到脂肪细胞形态的发展(即脂包涵体)。与这一表型变化相一致的是，3-磷酸甘油醛脱氢酶(GPDH)活性以及细胞内HepG2型(Glut1)和脂肪细胞/肌肉(GLUT4)葡萄糖转运体的细胞含量增加，这是通过细胞总蛋白的免疫印迹确定的。年龄匹配的未分化细胞表达Glut1转运体和低水平的GPDH，但既没有积累脂肪，也没有表现出可测量的GLUT4蛋白表达。在分化开始后的第6天，GH和胰岛素以剂量和时间依赖的方式刺激无血清条件下培养的脂肪细胞摄取2-脱氧[14C]葡萄糖至少15h，Western-印迹分析显示，GH和胰岛素都能迅速(在20min内)刺激Glut1和GLUT4蛋白从低密度微粒体组分向质膜移位。利用针对GLUT4蛋白C-末端区域的抗血清和异硫氰酸荧光素标记的第二抗体进行的免疫细胞化学实验提供了确凿的证据。激光共聚焦显微镜下观察到的细胞与GH或胰岛素处理后葡萄糖转运体从细胞内区域到质膜的重新分布是一致的。在这些数据的基础上，我们认为GH对脂肪细胞葡萄糖运输的胰岛素样作用涉及Glut1和GLUT4蛋白向质膜的移位。此外，生长激素和胰岛素对葡萄糖转运体转位的刺激可能表明脂肪细胞生长激素和胰岛素受体之间存在共同的细胞信号元件，或者，存在多种刺激葡萄糖转运体转位的细胞机制。
The cellular mechanism whereby growth hormone (GH) acutely stimulates adipocyte glucose uptake was studied in cultures of primary rat adipocytes differentiated in vitro. Preadipocytes were isolated by collagenase digestion of inguinal fat-pads from young rats and were differentiated in the presence of 3-isobutyl-1-methylxanthine, insulin and dexamethasone. The development of an adipocyte morphology (i.e. lipid inclusions) was observed over 6 days after initiation of differentiation. Coincident with this phenotypic change was an increase in glyceraldehyde-3-phosphate dehydrogenase (GPDH) activity and in cellular content of the HepG2-type (Glut1) and adipocyte/muscle (Glut4) glucose transporter isoforms as determined by Western immunoblotting of total cellular protein. Age-matched undifferentiated cells expressed the Glut1 transporter and low levels of GPDH, but neither accumulated lipid nor exhibited measurable expression of the Glut4 protein. On day 6 after the initiation of differentiation, GH and insulin stimulated 2-deoxy[14C]glucose uptake in a dose- and time-dependent fashion in adipocytes cultured under serum-free conditions for at least 15 h. Western-blot analysis of subcellular fractions revealed that both GH and insulin rapidly (within 20 min) stimulated translocation of the Glut1 and Glut4 proteins from a low-density microsomal fraction to the plasma membrane. Confirmatory evidence was provided in immunocytochemical experiments utilizing antisera directed against the C-terminal region of the Glut4 protein and a fluorescein isothiocyanate-labelled second antibody. Observation of the cells via confocal laser microscopic imaging was consistent with glucose transporter redistribution from an intracellular region to the plasma membrane after treatment with GH or insulin. On the basis of these data, we suggest that the insulin-like effect of GH on adipocyte glucose transport involves translocation of the Glut1 and Glut4 proteins to the plasma membrane. Furthermore, stimulation of glucose-transporter translocation by both GH and insulin may indicate a common cell signalling element between the adipocyte GH and insulin receptors or, alternatively, the existence of multiple cellular mechanisms for stimulating glucose-transporter translocation.