Regulation of the ovine intestinal Na+/glucose co-transporter (SGLT1) is dissociated from mRNA abundance.
Regulation of the ovine intestinal Na+/glucose co-transporter (SGLT1) is dissociated from mRNA abundance.
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绵羊肠道钠/葡萄糖协同转运蛋白 (SGLT1) 的调节与 mRNA 丰度无关。
DOI：
10.1042/bj2910435
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Shirazi-Beechey,SP
中科院分区：
文献类型：
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作者：
Lescale-Matys,L;Dyer,J;Scott,D;Freeman,TC;Wright,EM;Shirazi-Beechey,SP
我们研究了反刍动物Na+/葡萄糖协同转运蛋白（SGLT 1）的调节机制，这是研究肠道葡萄糖转运的特殊模型系统。反刍前羔羊通过顶端SGLT 1和基底外侧促进性葡萄糖转运蛋白（GLUT 2）吸收乳糖水解产生的葡萄糖。断奶与瘤胃的发育一致，因此到达反刍羊小肠的己糖量是不可检测的。在发育过程中，小肠刷状缘膜中的SGLT 1活性和丰度降低了200倍以上，无论是维持羔羊的牛奶添加剂饮食还是向绵羊肠道注入D-葡萄糖，都恢复了协同转运蛋白的活性和表达。我们测量了发育过程中绵羊肠道SGLT 1 mRNA水平，改变饮食，并将D-葡萄糖或甲基α-D-吡喃葡萄糖苷直接输注到肠腔中，以确定调节水平。在发育过程中，mRNA水平仅下降4倍。羔羊保持在一个牛奶蛋白质的饮食没有显示出变化的mRNA水平相对于年龄匹配的控制。最后，在反刍动物绵羊肠道输注糖后，D-葡萄糖输注使SGLT 1 mRNA增加，但仅增加2倍，而协同转运蛋白的数量和活性增加60-90倍。由于Na（+）依赖性葡萄糖转运活性的变化与SGLT 1蛋白丰度相关，并且由于mRNA水平的变化不能解释蛋白丰度的显著变化，因此我们得出结论，鲁米那糖对SGLT 1的主要调节水平是翻译或翻译后水平。
We have investigated the mechanisms of regulation of the Na+/glucose co-transporter (SGLT1) in a ruminant animal, which is an exceptional model system for studying intestinal glucose transport. Pre-ruminant lambs absorb glucose, produced by hydrolysis of the milk sugar lactose, in the intestine via apical SGLT1 and basolateral facilitative glucose transporters (GLUT2). Weaning coincides with the development of the rumen, and consequently the amount of hexoses reaching the small intestine of the ruminant sheep is undetectable. During development, SGLT1 activity and abundance in intestinal brush-border membranes decreased by over 200-fold, and either maintaining lambs on a milk replacer diet or infusing sheep intestine with D-glucose restored co-transporter activity and expression. We have measured ovine intestinal SGLT1 mRNA levels during development, with changes in diet and after direct infusion of D-glucose or methyl alpha-D-glucopyranoside into the intestinal lumen, in order to determine the level of regulation. During development, mRNA levels decreased only 4-fold. Lambs maintained on a milk replacer diet showed no change in mRNA levels relative to age-matched controls. Finally, upon infusion of the intestine of the ruminant sheep with sugars, D-glucose infusion increased SGLT1 mRNA, but only by 2-fold, compared with a 60-90-fold increase in co-transporter number and activity. Since the change in Na(+)-dependent glucose transport activity is correlated with SGLT1 protein abundance, and since changes in mRNA levels do not account for the dramatic changes in protein abundance, we conclude that the principal level of SGLT1 regulation by luminal sugar is translational or post-translational.