Cloning and expression of bovine sodium/glucose cotransporter SGLT2
Cloning and expression of bovine sodium/glucose cotransporter SGLT2
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DOI：
10.3168/jds.s0022-0302(05)72953-2
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发表时间：
2005-08-01
影响因子：
3.5
通讯作者：
Zheng, YC
中科院分区：
文献类型：
--
作者：
Zhao, FQ;McFadden, TB;Zheng, YC
Na+/葡萄糖协同转运蛋白家族的第二个成员SGLT 2是一种低亲和力活性葡萄糖转运蛋白。在人类中，它主要位于肾近曲小管S1和S2段的顶膜上，因此，可能主要负责从肾小球滤液中重吸收D-葡萄糖。通过BLAST检索GenBank数据库，在牛乳腺组织cDNA文库中发现了SGLT 2的表达序列标签序列，表明其在牛乳腺组织中有表达。为了便于研究牛肾脏中葡萄糖重吸收在维持泌乳奶牛葡萄糖稳态中的机制以及SGLT 2在乳腺中的潜在作用，我们克隆了牛SGLT 2并检测了其mRNA在牛组织中的表达分布。bSGLT 2的全长mRNA为2275 bp，预计编码673个氨基酸的蛋白质，分子量约为73 kDa。牛SGLT 2的推导氨基酸序列与人、兔、小鼠和大鼠SGLT 2的同源性分别为91、90、91和90%，与牛SGLT 1和SGLT 5的同源性分别为58和48%。bSGLT 2的序列包含几个特征性保守的钠：溶质同向转运体家族的签名。目前牛基因组数据的分析表明，牛SGLT 2基因可能由14个外显子组成。牛SGLT 2 cDNA的主要体外转录和翻译产物迁移的表观分子量为55 kDa。SGLT 2 mRNA主要在牛肾脏中以2.3 kb转录本检出，在所有其他检查的牛组织（包括乳腺、肝脏、肺、脾脏、肠和骨骼肌）中以较低水平以3.0 kb转录本检出。从妊娠晚期到泌乳早期，牛乳腺中SGLT 2 mRNA的表达增加了10倍以上，与SGLT 1相似。这表明SGLT 2可能在泌乳乳腺的乳汁合成中发挥作用。
The second member of the Na+/glucose cotransporter family, SGLT2, is a low-affinity active glucose transporter. In humans, it is predominantly located on the apical membrane of the S1 and S2 segments of renal proximal convoluted tubules, and, thus, may be mainly responsible for the reabsorption of D-glucose from the glomerular filtrate. By BLAST searching the GenBank database, we found expressed sequence tag sequences of SGLT2 in the cDNA library of bovine mammary tissues, indicating its expression in bovine mammary gland. To facilitate study of the mechanism of glucose reabsorption in bovine kidneys in maintenance of glucose homeostasis of lactating cows and the potential role of SGLT2 in the mammary gland, we cloned bovine SGLT2 and examined the distribution of its mRNA expression in bovine tissues. The full length mRNA of bSGLT2 is 2275 bp, and is predicted to encode a protein of 673 amino acids, with a molecular weight of approximately 73 kDa. The deduced amino acid sequence of bovine SGLT2 is 91, 90, 91, and 90% identical to human, rabbit, mouse, and rat SGLT2, respectively, and is 58 and 48% identical to bovine SGLT1 and SGLT5, respectively. The sequence of bSGLT2 contains several characteristically conserved sodium: solute symporter family signatures. Analysis of current bovine genomic data indicates that the bovine SGLT2 gene may consist of 14 exons. The major in vitro transcription and translation product of bovine SGLT2 cDNA migrated at an apparent molecular weight of 55 kDa. The SGLT2 mRNA was detected predominantly in bovine kidney as a 2.3-kb transcript, and at lower levels in all other bovine tissues examined, including the mammary gland, liver, lung, spleen, intestine, and skeletal muscle, as a 3.0-kb transcript. Expression of SGLT2 mRNA in bovine mammary gland increased more than 10-fold from late pregnancy to early lactation, similar to SGLT1. This indicates that SGLT2 may play a role in milk synthesis in the lactating mammary gland.