Mitani Y, Behrooz A, Dubyak G R, Ismail-Beigi F
Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4951, USA.
Am J Physiol. 1995 Nov;269(5 Pt 1):C1228-34. doi: 10.1152/ajpcell.1995.269.5.C1228.
We tested the hypothesis that an increase in cytosolic calcium concentration stimulates glucose transporter isoform (GLUT-1) gene expression. Exposure of a rat liver cell line (Clone 9) to 3 microM A-23187 for 12 h resulted in 3-, 5-, and 10-fold increases in cytochalasin B-inhibitable 3-O-methyl-D-glucose transport, GLUT-1 protein, and GLUT-1 mRNA content, respectively. The induction of GLUT-1 mRNA in response to A-23187 is not preceded by a significant decrease in cell ATP content. This induction is prevented by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid in conjunction with ethylene glycol-bis(beta-aminoethyl ether)-N,N, N',N'-tetraacetic acid. To investigate the mechanism of GLUT-1 mRNA induction, we found that exposure to A-23187 stabilized GLUT-1 mRNA: with the employment of actinomycin D, GLUT-1 mRNA had a half-life of 1.5 and 5.5 h in control and A-23187-treated cells, respectively. In nuclear run-on assays, the rate of GLUT-1 gene transcription was stimulated 1.5- to 1.7-fold in nuclei isolated from cells exposed to A-23187 for either 30 min or 2 h. These results demonstrate that exposure to A-23187 stimulates GLUT-1 gene expression and that the increase in GLUT-1 mRNA content is mediated in part by enhanced GLUT-1 gene transcription as well as decreased GLUT-1 mRNA degradation. The increase in GLUT-1 mRNA content, in turn, is associated with increased cell GLUT-1 content and enhanced glucose transport.
我们验证了胞质钙浓度升高会刺激葡萄糖转运体异构体（GLUT-1）基因表达这一假说。将大鼠肝细胞系（克隆9）暴露于3 microM的A-23187中12小时，结果细胞松弛素B可抑制的3-O-甲基-D-葡萄糖转运、GLUT-1蛋白及GLUT-1 mRNA含量分别增加了3倍、5倍和10倍。A-23187诱导GLUT-1 mRNA的表达之前，细胞ATP含量并未显著下降。1,2-双（2-氨基苯氧基）乙烷-N,N,N',N'-四乙酸与乙二醇-双（β-氨基乙基醚）-N,N,N',N'-四乙酸联合使用可阻止这种诱导作用。为研究GLUT-1 mRNA诱导的机制，我们发现暴露于A-23187可使GLUT-1 mRNA稳定：使用放线菌素D后，在对照细胞和A-23187处理的细胞中，GLUT-1 mRNA的半衰期分别为1.5小时和5.5小时。在核转录分析中，从暴露于A-23187 30分钟或2小时的细胞中分离得到的细胞核中，GLUT-1基因转录速率提高了1.5至1.7倍。这些结果表明，暴露于A-23187会刺激GLUT-1基因表达，且GLUT-1 mRNA含量的增加部分是由GLUT-1基因转录增强以及GLUT-1 mRNA降解减少介导的。GLUT-1 mRNA含量的增加进而与细胞GLUT-1含量增加及葡萄糖转运增强相关。
