鸭TTR基因cDNA克隆和表达研究

Molecular cloning and expression profiles of TTR gene in ducks

为研究转甲状腺素蛋白(transthyretin,TTR)与肉鸭脂肪代谢的相关性,通过快速扩增cDNA末端技术(RACE)获得北京鸭TTR基因全长cDNA序列,并采用实时荧光定量PCR法对鸭TTR基因表达谱进行研究。结果显示:鸭全长TTRmRNA编码150个氨基酸的前体肽,该肽含20个氨基酸的信号肽和130个氨基酸的成熟肽;与哺乳动物相比,鸭TTR亚基N-末端序列多出的3个氨基酸Val-Ser-His,可能使鸭TTR结合甲状腺素T3的亲合力增加。定量检测结果表明,鸭TTRmRNA在脉络丛中的表达量最高,与鸡、爬行类和哺乳动物类似。本实验证实鸭TTR基因在脉络丛中的表达量比鸡更高,并首次发现TTRmRNA在鸭皮下脂肪组织中表达。

Full-length cDNA encoding transthyretin （TTR）, a thyroid hormone-binding protein, of Pekin ducks was isolated by means of rapid amplification of cDNA ends （RACE） to investigate the potential involvement of TTR gene in duck lipogenesis, The full-length duck TTR mRNA encodes a single polypeptide of 150 amino acids, which consists of a signal peptide of 20 amino acids and a mature peptide of 130 amino acids, similar to the chicken counterpart. A structure of three extra amino acids, -Val-Ser-His, near the amino terminus of TTR subunit, which could lead to an increase in T3-binding affinity of the avian TTR, is conserved between in the duck and in the chicken. Expression profile of TTR gene in the duck was measured using real-time quantitative PCR （qRT-PCR）. The highest concentration of TTR mRNA was detected in the choroid plexus, similar to those in the chicken, reptiles and mammals. Moreover, the expression abundance of TTR gene in choroid plexus was higher in the duck than in the chicken. It was also demonstrated that the TTR mRNA expressed in the fat tissues of ducks, especially in subcutaneous fat.