大黄鱼IL-7-Rα基因的克隆与表达分析
Cloning and expression analysis of Larimichthys crocea IL-7-Rα gene
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摘要: 白细胞介素7受体α链（IL-7Rα，CD127）是一个重要的多效性细胞因子受体.本研究克隆得到大黄鱼（Larimichthys crocea）的IL-7Rα（LycIL-7-Rα），其开放阅读框全长1 242 bp，编码413个氨基酸.通过氨基酸序列分析和多序列比对发现，LycIL-7Rα多肽具有I型细胞因子受体的典型特征，包括4个保守的半胱氨酸、1个信号肽、1个单次跨膜结构域、1个胞外的fibronectin type III（FN III-like）结构域、1个Trp-Ser-X-Trp-Ser （WSXWS）基序以及胞内Box1结构域.系统进化分析表明，LycIL-7Rα与其他鱼类的IL-7Rα聚在一起，与鲈鱼（Lates calcarifer）IL-7Rα的亲缘关系最近.Real-time PCR结果表明，LycIL-7-Rα在健康大黄鱼中为组成型表达，在脾脏中的表达量最高，在心脏中的表达量最低.大黄鱼经聚肌苷酸胞苷酸［Poly（I：C）］或溶藻弧菌（Vibrio alginolyticus）刺激后，其脾脏中LycIL-7Rα的mRNA转录水平均显著上调.这些结果表明 LycIL-7Rα可能在大黄鱼免疫反应中发挥重要作用.Abstract: The IL-7 receptor alpha chain （IL-7Rα，CD127） is an important pleiotropic receptor in immunology. In this paper， we cloned an IL-7Rα homologue from Larimichthys crocea and named it as LycIL-7-Rαv. The deduced open reading frame （ORF） of LycIL-7Rα is 1 242 base pair （bp） long， encoding a protein consisting of 413 amino acids （aa）. Amino acid sequence alignment revealed that LycIL-7Rα protein exhibits typical domain architecture of type I cytokine receptors， including 4 conserved cysteine residues， a signal peptide， an extracellular FN III-like domain， a Trp-Ser-X-Trp-Ser （WSXWS） motif， a transmembrane region and an intracellular Box1 domain. Phylogenetic analysis shows that LycIL-7Rα fell into a clade formed by all fish IL-7Rα and was closely related to IL-7Rα of barramundi perch （Lates calcarifer）. Real-time PCR results shows that LycIL-7RαmRNA was constitutively expressed in all tissues tested， with highest expression level in spleen and lowest in heart. Moreover， the transcription levels of LycIL-7Rα mRNA are significantly upregulated in spleen after stimulated by polyinosinic acid cytidine ［Poly （I：C）］ or Vibrio alginolyticus. These results indicate that LycIL-7Rα may play roles in immune responses in the large yellow croaker.
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