圆斑星鲽MHCⅠα基因的克隆与组织表达分析

Molecular Cloning and Tissue Expression Analysis of MHCⅠα from Spotted Halibut(Verasper variegates)

采用表达序列标签法和cDNA末端快速扩增（RACE）技术,成功获得了圆斑星鲽主要组织相容性复合体MHCⅠα的全长cDNA序列。该cDNA全长2171 bp,5′UTR为20 bp,3′UTR为1053bp,开放阅读框（ORF）长度为1098 bp,可编码365个氨基酸,包含信号肽、抗原结合域（α1、α2）,IGC类似区（α3）,连接肽（跨膜区）和胞质区5个结构域。同源分析表明,圆斑星鲽MHCⅠα氨基酸序列与其他硬骨鱼具有31%~74%的同源性,与人的相似性较低。利用荧光定量PCR分析组织表达发现MHCⅠα基因在健康圆斑星鲽9种组织中均有表达,但表达量存在差异,肾的表达量最高,肌肉和皮的表达量最低。

Major histocompatibility complex（MHC） which functions genes play an important role in the immune response of vertebrates.In the present study,the full length cDNA of MHCⅠα was obtained from the spotted halibut（Verasper variegatus） by expressed sequence tag（EST） and rapid amplification of cDNA ends（RACE）.The full length cDNA was of 2173 bp,consisting of a 5′-terminal untranslated region（UTR） of 20 bp,a 3′-UTR of 1053 bp with a poly（A） tail,and an open reading frame（ORF） of 1098 bp encoding a polypeptide of 365 amino acids,which encoded a signal peptide,a peptide binding region（α1,α2）,an immunoglobulin-like region（α3）,a transmembrane region,and a cytoplasmic region.The deduced amino acid sequence of spotted halibut MHCⅠα shared 31%~74% identity with that of other teleosts.Quantitative Real-time RT-PCR analysis demonstrated that MHCⅠα was ubiquitously expressed in all tested tissues,but the expression level was locally unique.The MHCⅠα transcript was detected at a high level in kidney and intestine,moderate in gill,liver and spleen,and low in skin,muscle,blood and heart.