Regulation of glucose transport as well as glucose transporter and immediate early gene expression in 3T3-L1 preadipocytes by 8-bromo-cAMP.
Regulation of glucose transport as well as glucose transporter and immediate early gene expression in 3T3-L1 preadipocytes by 8-bromo-cAMP.
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8-溴-cAMP 对 3T3-L1 前脂肪细胞中葡萄糖转运以及葡萄糖转运蛋白和立即早期基因表达的调节。
DOI：
10.1002/jcp.1041460215
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发表时间：
1991
影响因子：
5.6
通讯作者：
Pekala,PH
中科院分区：
文献类型：
--
作者：
Cornelius,P;Marlowe,M;Call,K;Pekala,PH
在本研究中，我们检测了8-溴腺苷环3′，5′-磷酸（8-溴-cAMP; cAMP的膜渗透类似物，可激活蛋白激酶A）模拟激素作用并刺激葡萄糖转运和葡萄糖转运蛋白（GLUT-1）基因表达以及静止3 T3-L1成纤维细胞中几种生长相关原癌基因表达的能力。8-Bromo-cAMP诱导己糖转运速率快速且长期增加。己糖转运的早期激活（30分钟内）与质膜免疫反应性葡萄糖转运蛋白增加相关，这对应于D-葡萄糖可置换的质膜细胞松弛素B结合位点数量加倍。8-溴-cAMP诱导的己糖转运的时间过程先于GLUT-1 mRNA的积累，GLUT-1 mRNA在暴露于该试剂后4 - 8 h达到峰值，随后下降至接近基础（对照）水平。8-bromo-cAMP可快速但持续地诱导即刻早期基因c-fos和jun-B的表达，而c-jun表达的诱导则延迟。暴露于8-溴-cAMP后特定mRNA的改变是由于基因转录增加（通过核转录连续试验判断），尽管对于GLUT-1，也观察到mRNA稳定性增加。用毛喉素处理细胞导致GLUT-1表达的诱导以及立即早期基因的表达。将静止的3 T3-L1成纤维细胞暴露于8-溴-cAMP导致总蛋白和RNA合成速率大幅增加，但对DNA合成几乎没有影响。结果表明，8-溴-cAMP启动了G 0/G1转变，但不允许进展到S期。结果进一步表明，细胞溶质cAMP增加通过三种不同的机制刺激葡萄糖转运，包括预先存在的转运蛋白的易位、GLUT-1基因转录增加和GLUT-1 mRNA稳定性增加。
In the present study we have examined the ability of 8‐bromoadenosine cyclic 3′, 5′‐phosphate (8‐bromo‐cAMP; the membrane permeant analog of cAMP which can activate protein kinase A) to mimic hormone action and stimulate glucose transport and glucose transporter (GLUT‐1) gene expression as well as the expression of several growth‐related protooncogenes in quiescent 3T3‐L1 fibroblasts. 8‐Bromo‐cAMP induced a rapid and prolonged increase in the rate of hexose transport. Early activation of hexose transport (within 30 min) was associated with increased plasma membrane immunoreactive glucose transporters, which corresponded to a doubling in the number of D‐glucose‐displaceable, plasma membrane cytochalasin B binding sites. The time course for 8‐bromo‐cAMP‐induced hexose transport preceded the accumulation of GLUT‐1 mRNA, which peaked between 4 and 8 h after exposure to the agent, and subsequently declined to approach basal (control) levels. Expression of the immediate‐early genes c‐fos and jun‐B was induced by 8‐bromo‐cAMP on a rapid, but sustained time course, whereas induction of c‐jun expression was delayed. Alterations in specific mRNAs following exposure to 8‐bromo‐cAMP were due to increased gene transcription (as judged by nuclear transcription run‐on assays), although with respect to GLUT‐1, an increase in mRNA stability was also observed. Treatment of the cells with forskolin resulted in the induction of GLUT‐1 expression as well as expression of the immediate early genes. Exposure of quiescent 3T3‐L1 fibroblasts to 8‐bromo‐cAMP resulted in a substantial increase in rates of total protein and RNA synthesis, but had little effect on DNA synthesis. The results demonstrate that 8‐bromo‐cAMP initiated a G0/G1transition, but did not permit progression into S‐phase. The results further suggest that increased cytosolic cAMP results in the stimulation of glucose transport by three distinct mechanisms to include translocation of pre‐existing transporters, increased transcription of the GLUT‐1 gene and increased stability of GLUT‐1 mRNA.