Oka Y, Asano T, Shibasaki Y, Lin J L, Tsukuda K, Akanuma Y, Takaku F
Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Hongo, Japan.
Diabetes. 1990 Apr;39(4):441-6. doi: 10.2337/diab.39.4.441.
The effect of insulin-deficient diabetic states on the rat liver glucose-transporter (L-transporter isoform) protein and mRNA levels were studied. Rats were injected with 65 mg/kg streptozocin to induce diabetes and were maintained for 10 days and then treated with or without insulin for the next 5 days. The L-transporter isoform with apparent Mr of 55,000 was observed to be increased approximately twofold in the membranes from liver homogenates of diabetic rats compared with control rats when assessed by Western blot analysis with an anti-peptide antibody directed against rat L-transporter isoform. Insulin treatment of diabetic rats decreased the amount of L-transporter isoform protein toward levels observed in nondiabetic rats. Northern blot analysis demonstrated similar alterations in the rat L-transporter isoform mRNA that paralleled the changes observed in the L-transporter isoform protein. The increased levels of the L-transporter isoform protein and mRNA in diabetic rats are in marked contrast to the effects of insulin deficiency in rat adipocytes, which specifically decrease the amount of the adipocyte glucose-transporter isoform protein and mRNA. These results suggest that glucose-transporter isoforms in rat liver and adipocytes are regulated by different mechanisms and that an increased synthesis of the L-transporter isoform may contribute to the increased glucose output that occurs from the liver during insulin deficiency.
研究了胰岛素缺乏的糖尿病状态对大鼠肝脏葡萄糖转运蛋白（L-转运蛋白异构体）蛋白质和mRNA水平的影响。给大鼠注射65mg/kg链脲佐菌素以诱导糖尿病，并维持10天，然后在接下来的5天给予或不给予胰岛素治疗。当用针对大鼠L-转运蛋白异构体的抗肽抗体通过蛋白质印迹分析评估时，观察到与对照大鼠相比，糖尿病大鼠肝脏匀浆膜中表观分子量为55,000的L-转运蛋白异构体增加了约两倍。对糖尿病大鼠进行胰岛素治疗可使L-转运蛋白异构体蛋白的量降至非糖尿病大鼠中观察到的水平。Northern印迹分析表明，大鼠L-转运蛋白异构体mRNA有类似变化，与L-转运蛋白异构体蛋白中观察到的变化平行。糖尿病大鼠中L-转运蛋白异构体蛋白和mRNA水平的升高与胰岛素缺乏对大鼠脂肪细胞的影响形成鲜明对比，胰岛素缺乏会特异性降低脂肪细胞葡萄糖转运蛋白异构体蛋白和mRNA的量。这些结果表明，大鼠肝脏和脂肪细胞中的葡萄糖转运蛋白异构体受不同机制调节，并且L-转运蛋白异构体合成增加可能导致胰岛素缺乏期间肝脏葡萄糖输出增加。
