Peptide purification, complementary deoxyribonucleic acid (DNA) and genomic DNA cloning, and functional characterization of ghrelin in rainbow trout
Peptide purification, complementary deoxyribonucleic acid (DNA) and genomic DNA cloning, and functional characterization of ghrelin in rainbow trout
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DOI：
10.1210/en.2003-1085
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发表时间：
2003-12-01
期刊：
影响因子：
4.8
通讯作者：
Kangawa, K
中科院分区：
文献类型：
--
作者：
Kaiya, H;Kojima, M;Kangawa, K
我们已经从彩虹鲑鱼的胃中鉴定出Ghrelin。Ghrelin的四种异构体被分离出来：由24个氨基酸组成的C末端酰胺化型虹鱼Ghrelin(RT Ghrelin)是一种基本形式，Des-VRQ-RT ghrelin从RT ghrelin中删除了三个氨基酸(V(13)R(14)Q(15))，另外两种RT ghrelin保留了C端的甘氨酸残基，RT ghrelin-Gly和Des-VRQ-RT ghrelin。第三个丝氨酸残基被辛酸、癸酸或这些脂肪酸的不饱和形式修饰。与分离的多肽一致，分离到两个不同长度的cDNA。RT ghrelin基因有5个外显子和4个内含子，预测该基因的选择性剪接会产生两个不同的mRNA分子。在胃中检测到高水平的ghrelin mRNA表达，在脑、下丘脑和肠道中检测到中等水平的表达。DES-VRQ-RT Ghrelin可促进大鼠体内GH的释放。此外，DES-VRQ-RT Ghrelin在体内和体外都能促进虹鱼生长激素的释放，但不能促进催乳素和生长激素的释放。这些结果表明，Ghrelin是一种新的生长激素促分泌剂，可能通过生长激素影响体细胞生长或渗透调节。由于Ghrelin在胃以外的各种组织中都有表达，它可能作为局部调节因子在细胞功能中发挥重要作用(S)。
We have identified ghrelin from the stomach of rainbow trout. Four isoforms of ghrelin peptide were isolated: the C-terminal amidated type of rainbow trout ghrelin (rt ghrelin) composed of 24 amino acids (GSSFLSPSQKPQVRQGKGKPPRV- amide) is a basic form; des-VRQ-rt ghrelin, which deleted three amino acids (V(13)R(14)Q(15)) from rt ghrelin; and further two types of rt ghrelin that retained the glycine residue at the C terminus, rt ghrelin-Gly, and des-VRQ-rt ghrelin-Gly. The third serine residue was modified by octanoic acid, decanoic acid, or the unsaturated form of those fatty acids. In agreement with the isolated peptides, two cDNAs of different lengths were isolated. The rt ghrelin gene has five exons and four introns, and two different mRNA molecules are predicted to be produced by alternative splicing of the gene. A high level of ghrelin mRNA expression was detected in the stomach, and moderate levels were detected in the brain, hypothalamus, and intestinal tracts. Des-VRQ-rt ghrelin stimulated the release of GH in the rat in vivo. Furthermore, des-VRQ-rt ghrelin stimulated the release of GH, but not the release of prolactin and somatolactin in rainbow trout in vivo and in vitro. These results indicate that ghrelin is a novel GH secretagogue in rainbow trout that may affect somatic growth or osmoregulation through GH. Because ghrelin is expressed in various tissues other than stomach, it may play important role(s) in cellular function as a local regulator.