3T3-L1 adipocyte glucose transporter (HepG2 class): sequence and regulation of protein and mRNA expression by insulin, differentiation, and glucose starvation.
3T3-L1 adipocyte glucose transporter (HepG2 class): sequence and regulation of protein and mRNA expression by insulin, differentiation, and glucose starvation.
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3T3-L1 脂肪细胞葡萄糖转运蛋白（HepG2 类）：胰岛素、分化和葡萄糖饥饿对蛋白质和 mRNA 表达的序列和调节。
DOI：
10.1016/0003-9861(90)90490-p
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发表时间：
1990
影响因子：
3.9
通讯作者：
Vang,M
中科院分区：
文献类型：
--
作者：
Reed,BC;Shade,D;Alperovich,F;Vang,M
从小鼠3T3-L1脂肪细胞中分离葡萄糖转运蛋白cDNA （GLUT）克隆并测序。核苷酸和推断的氨基酸序列与大鼠脑转运蛋白的同源性分别为95%和99%。利用小鼠cDNA和识别相应体外翻译产物的多克隆抗体，比较3T3-L1前脂肪细胞在分化、葡萄糖饥饿和慢性胰岛素暴露期间转运蛋白mRNA和蛋白水平的变化。在分化过程中，转运体mRNA和蛋白质的细胞含量分别增加了6.6倍和7.8倍，在分化的脂肪细胞中，慢性胰岛素暴露分别增加了3.8倍和2.5倍。葡萄糖饥饿使未分化前脂肪细胞的转运蛋白mRNA和蛋白质水平分别增加2.2倍和3.5倍，而已分化脂肪细胞的转运蛋白mRNA和蛋白质水平分别增加1.8倍和3.1倍。未分化细胞的饥饿将天然转运蛋白完全转化为不完全糖基化的形式，同时将基础转运率提高4.5倍。要么完全糖基化不需要产生功能活跃的转运蛋白，要么饥饿导致通常不存在的“反应性”转运蛋白的独特预分化诱导。分化引起的转运蛋白表达的变化主要归因于转运蛋白合成速率的增加，而慢性胰岛素治疗和饥饿引起的mRNA和蛋白质表达的不成比例的变化表明，这些条件增加了转运蛋白表达的合成，降低了转运蛋白表达的周转率。虽然慢性胰岛素暴露和葡萄糖饥饿均使转运蛋白的表达增加3倍以上，基础转运率增加2.5- 4.5倍，但未观察到3T3-L1前脂肪细胞或分化脂肪细胞的胰岛素反应性显著增加。因此，本研究中观察到的转运蛋白mRNA和蛋白表达的变化与它们与基础或低水平胰岛素反应转运蛋白的调节表达相关最为一致。
A glucose transporter cDNA (GLUT) clone was isolated from mouse 3T3-L1 adipocytes and sequenced. The nucleotide and deduced amino acid sequences were, respectively, 95 and 99% homologous to those of the rat brain transporter. The mouse cDNA and a polyclonal antibody recognizing the correspondingin vitrotranslation product were used to compare changes in transporter mRNA and protein levels during differentiation, glucose starvation, and chronic insulin exposure of 3T3-L1 preadipocytes. The respective cellular content of transporter mRNA and protein were increased 6.6- and 7.8-fold during differentiation, and 3.8- and 2.5- fold from chronic insulin exposure of differentiated adipocytes. Glucose starvation increased transporter mRNA and protein levels 2.2- and 3.5-fold in undifferentiated preadipocytes and 1.8- and 3.1-fold in differentiated adipocytes. Starvation of undifferentiated cells completely converted the native transporter to an incompletely glycosylated form, while increasing basal transport rates 4.5-fold. Either full glycosylation is not required to produce a functionally active transporter, or starvation causes a unique predifferentiation induction of the normally absent “responsive” transporter. The changes in transporter protein expression elicited by differentiation were attributed primarily to increased rates of transporter synthesis, while the disproportionate changes in mRNA and protein expression from chronic insulin treatment and starvation suggested these conditions increase synthesis and decrease turnover rates in regulating transporter protein expression. Although chronic insulin exposure and glucose starvation each raised the expression of transporter protein greater than 3-fold and basal transport rates 2.5- to 4.5-fold, no significant increase in the insulin responsiveness of 3T3-L1 preadipocytes or differentiated adipocytes was observed. Thus, the changes in the transporter mRNA and protein expression observed in this study were most consistent with their being associated with the regulated expression of a basal or low level insulin-responsive transporter.