CLONING AND MOLECULAR CHARACTERIZATION OF THE ONTOGENY OF A RAT ILEAL SODIUM-DEPENDENT BILE-ACID TRANSPORTER
CLONING AND MOLECULAR CHARACTERIZATION OF THE ONTOGENY OF A RAT ILEAL SODIUM-DEPENDENT BILE-ACID TRANSPORTER
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DOI：
10.1172/jci117722
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发表时间：
1995-02-01
影响因子：
15.9
通讯作者：
SUCHY, FJ
中科院分区：
文献类型：
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作者：
SHNEIDER, BL;DAWSON, PA;SUCHY, FJ
大鼠回肠中钠依赖性胆汁酸转运在断奶时突然表达。基于大鼠肝脏和仓鼠回肠转运蛋白之间的氨基酸序列同一性，简并寡核苷酸被用来扩增大鼠回肠探针。通过杂交筛选分离出包含完整编码区（348 个氨基酸，38 kD）的 1.2 kb cDNA 克隆。体外翻译产生了 38 kD 的蛋白质，该蛋白质糖基化为 48 kD。在注射 cRNA 的卵母细胞中观察到牛磺胆酸盐的钠依赖性摄取。 Northern 印迹分析显示回肠、肾脏和盲肠中存在 5.0-kb mRNA。在回肠刷状缘膜中检测到 48 kD 蛋白，该蛋白定位于绒毛回肠肠细胞的顶缘。断奶前可忽略不计的 mRNA 和蛋白质表达在断奶后急剧增加。转运蛋白的核转录率在出生后第 7 天至第 28 天之间增加了 15 倍。转运蛋白的表观分子量在第 19 天至第 28 天之间也增加。总而言之，大鼠回肠钠依赖性胆汁酸协同转运蛋白的发育调节的特点是断奶时 mRNA 和蛋白质水平的转录调节增加，以及断奶后蛋白质表观分子量的变化。
Sodium-dependent bile acid transport in the rat ileum is abruptly expressed at weaning. Degenerate oligonucleotides, based on amino acid sequence identities between the rat liver and hamster ileal transporters, were used to amplify a rat ileal probe. A 1.2-kb cDNA clone, which contains the full coding region (348 amino acids, 38 kD), was isolated by hybridization screening. In vitro translation yielded a 38-kD protein which glycosylated to 48 kD. Sodium-dependent uptake of taurocholate was observed in oocytes injected with cRNA. Northern blot analysis revealed a 5.0-kb mRNA in ileum, kidney, and cecum. A 48-kD protein was detected in ileal brush border membranes and localized to the apical border of villus ileal enterocytes. mRNA and protein expression, which were negligible before weaning, increased dramatically at weaning. Nuclear transcription rates for the transporter increased 15-fold between postnatal days 7 and 28. The apparent molecular weight of the transporter also increased between days 19 and 28. In summary, the developmental regulation of the rat ileal sodium-dependent bile acid cotransporter is characterized by transcriptionally regulated increases in mRNA and protein levels at the time of weaning with changes in apparent molecular weight of the protein after weaning.