Kishi K, Tanaka T, Igawa M, Takase S, Goda T
Department of Nutrition, School of Food and Nutritional Sciences, The University of Shizuoka, Japan.
J Nutr. 1999 May;129(5):953-6. doi: 10.1093/jn/129.5.953.
We previously demonstrated that the levels of mRNAs of both sucrase-isomaltase (SI) and sodium/D-glucose transporter (SGLT1) are modulated by dietary sucrose in the rat jejunum. In the present study, we investigated whether the transcription of the gene coding SI is regulated by certain types of monosaccharides. Force-feeding a fructose and sucrose diet, (40% energy as fructose or sucrose) gave rise to parallel increases in the transcripts of SI and intestinal hexose transporters (SGLT1, GLUT5, and GLUT2) within 12 h. Force-feeding a glycerol-containing diet also caused an enhancement of SI, SGLT1, and GLUT2 mRNA levels. However, feeding the diet containing glucose or alpha-methylglucoside generally did not increase the transcript levels of SI or the intestinal hexose transporters. Nuclear run-on assays revealed that fructose as well as sucrose increased the transcription of both SI and GLUT5 genes and that the transcription rates of these genes were unaffected by glucose. These results suggest that fructose (or a metabolite) is capable of increasing the mRNA levels of SI and hexose transporters in the small intestine and that transcriptional regulation might play a pivotal role in the carbohydrate-induced coordinate enhancement of SI and fructose transporter gene expression
我们先前证明，蔗糖酶-异麦芽糖酶（SI）和钠/葡萄糖转运蛋白（SGLT1）的mRNA水平在大鼠空肠中受膳食蔗糖调节。在本研究中，我们调查了编码SI的基因转录是否受某些类型单糖的调控。强制喂食果糖和蔗糖饮食（40%能量来自果糖或蔗糖）在12小时内使SI和肠道己糖转运蛋白（SGLT1、GLUT5和GLUT2）的转录本平行增加。强制喂食含甘油的饮食也导致SI、SGLT1和GLUT2 mRNA水平升高。然而，喂食含葡萄糖或α-甲基葡萄糖苷的饮食通常不会增加SI或肠道己糖转运蛋白的转录本水平。细胞核转录分析显示，果糖以及蔗糖增加了SI和GLUT5基因的转录，并且这些基因的转录速率不受葡萄糖影响。这些结果表明，果糖（或一种代谢产物）能够增加小肠中SI和己糖转运蛋白的mRNA水平，并且转录调控可能在碳水化合物诱导的SI和果糖转运蛋白基因表达的协同增强中起关键作用。
