Nur T, Sela I, Webster N J, Madar Z
Department of Biochemistry and Human Nutrition, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel.
J Nutr. 1995 Oct;125(10):2457-62. doi: 10.1093/jn/125.10.2457.
Starvation and refeeding affect glycogen metabolism. The effects of starvation and refeeding on the level of glycogen synthase (GS) gene expression were examined in rat liver. Depletion of hepatic glycogen stores by 72 h of starvation (7% of control) was supercompensated by 24 h of refeeding a standard laboratory diet (247% of control). Upon further refeeding, glycogen concentration gradually returned to control levels after 120 h. After 72 h of starvation, GS activity and immunoreactive protein in the liver were 60-64% lower than in control rats with free access to food. After 72 h of refeeding, GS activity and immunoreactive protein returned to control values. No significant differences in GS mRNA levels were found between fed, starved and refed rats, as determined by Northern blot analysis and PCR quantification, indicating that the long-term regulation of GS gene expression in starvation and refeeding occurs via a posttranscriptional mechanism. The amount of GS mRNA associated with polyribosomes was 90% lower in starved than in fed rats. These data indicate that the efficiency of GS mRNA translation, rather than its abundance, decreases during starvation.
饥饿和再喂养会影响糖原代谢。研究了饥饿和再喂养对大鼠肝脏中糖原合酶（GS）基因表达水平的影响。饥饿72小时会使肝脏糖原储备减少（降至对照组的7%），而重新喂食标准实验室饮食24小时后，糖原储备会得到超量补偿（达到对照组的247%）。继续再喂养后，糖原浓度在120小时后逐渐恢复到对照水平。饥饿72小时后，肝脏中的GS活性和免疫反应性蛋白比自由进食的对照大鼠低60 - 64%。再喂养72小时后，GS活性和免疫反应性蛋白恢复到对照值。通过Northern印迹分析和PCR定量测定，发现喂食、饥饿和再喂养的大鼠之间GS mRNA水平无显著差异，这表明饥饿和再喂养过程中GS基因表达的长期调节是通过转录后机制发生的。与多核糖体相关的GS mRNA量在饥饿大鼠中比在喂食大鼠中低90%。这些数据表明，在饥饿期间，GS mRNA翻译的效率而非其丰度降低。
