Isolation, polymorphism and expression study of two distinct major histocompatibility complex class II B genes from half-smooth tongue sole (Cynoglossus semilaevis)
Isolation, polymorphism and expression study of two distinct major histocompatibility complex class II B genes from half-smooth tongue sole (Cynoglossus semilaevis)
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DOI：
10.1111/j.1744-313x.2010.00909.x
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发表时间：
2010-06-01
影响因子：
2.2
通讯作者：
Zhang, Q.
中科院分区：
文献类型：
--
作者：
Li, C.;Yu, Y.;Zhang, Q.
主要组织相容性复合体（MHC）Ⅱ类抗原是脊椎动物免疫系统中重要的抗原，它将多肽呈递给CD4 + T细胞。本研究从半滑舌鳎（Cynoglossus semilaevis）cDNA文库中克隆了编码MHC Ⅱ类B基因的cDNA，并通过PCR快速扩增cDNA末端，获得了全长cDNA序列。研究了其开放阅读框架、3 '非翻译区和内含子1的多态性。从9个个体中鉴定出19个II类B等位基因，并将其聚为两组，命名为Cyse-DAB和Cyse-DB B。Cyse-DAB和Cyse-DBB等位基因之间推导的氨基酸序列同源性分别为94.0%~99.6%和92.4%~99.6%，而Cyse-DAB和Cyse-DBB基因之间的同源性为85.1%~92.0%。在2个个体中各检测到3个Cyse-DAB等位基因和1个Cyse-DBB等位基因，在另1个个体中检测到3个Cyse-DBB等位基因和1个Cyse-DAB等位基因，表明每个基因至少存在2个位点。结果表明，该基因的3 '端非翻译区序列有两个，一个属于Cyse-DAB，另一个属于Cyse-DBB。从基因组序列中鉴定出5个Cyse-DAB和5个Cyse-DBB内含子1序列，其中每个基因在同一个体中鉴定出2个序列，表明至少存在2个Cyse-DAB和2个Cyse-DBB基因座。利用RT-PCR技术研究了两个基因的组织特异性和发育阶段特异性表达，结果表明两个基因在组织中的表达模式相似，在脾脏和肾脏中表达量较高，在肝脏、鳃和卵巢中表达量较低，在脑、心脏、肠和睾丸中表达量中等。而在发育分析中，Cyse-DBB基因在早期发育阶段的表达量高于Cyse-DAB基因，说明两个基因在早期发育阶段可能有不同的功能。因此，在半滑舌鳎中，存在两种不同的MHC II类B基因，并且无论是通过序列分析还是通过发育阶段表达研究都可以将其区分开来。
P>Major histocompatibility complex (MHC) class II antigens are important in vertebrate immune system, which present peptides to CD4+ T cells. In the present study, cDNAs encoding MHC class II B gene were isolated from the cDNA library of half-smooth tongue sole (Cynoglossus semilaevis), and the full length cDNA sequences were got by rapid amplification of cDNA ends polymerase chain reaction. The polymorphism of its open reading frame, 3' untranslated region and intron 1 was studied. Nineteen class II B alleles were identified from nine individuals and clustered into two groups, designated as Cyse-DAB and Cyse-DBB. The deduced amino acid sequences among Cyse-DAB and Cyse-DBB alleles shared identities from 94.0% to 99.6% and 92.4% to 99.6%, respectively, while the identities between Cyse-DAB and Cyse-DBB genes varied from 85.1% to 92.0%. Three Cyse-DAB alleles and one Cyse-DBB allele were observed in each of two individuals, and three Cyse-DBB alleles and one Cyse-DAB allele in another individual, which indicated at least two loci existed in each gene. Two different 3' UTR sequences were identified and one belonged to Cyse-DAB, the other belonged to Cyse-DBB. Both five Cyse-DAB and five Cyse-DBB intron 1 sequences were identified from genomic sequences, among which two sequences of each gene were identified in a single individual, which suggested the existence of at least two Cyse-DAB and two Cyse-DBB loci. Both the two genes'-specific tissue and developmental stage expression were studied by reverse-transcription polymerase chain reaction, which showed that the two genes had similar expression patterns in tissue study with high expression in spleen and kidney, low expression in liver, gill and ovary, moderate expression in brain, heart, intestine and testis. While in developmental analysis, Cyse-DBB had higher expression than Cyse-DAB in early developmental stages, which indicated that the two genes might have different functions in those stages. Therefore, in half-smooth tongue sole, two different MHC class II B genes exist and could differentiate from each other whether by sequence analysis or by developmental stage expression study.