College of Animal Science and Technology, College of Veterinary Medicine, Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology On Green-Eco-Healthy Animal Husbandry of Zhejiang Province, Hangzhou, China.
Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, China.
Immunogenetics. 2023 Dec;75(6):531-541. doi: 10.1007/s00251-023-01322-8. Epub 2023 Oct 7.
All jawed vertebrates have four T cell receptor (TCR) chains expressed by thymus-derived lymphocytes that play a significant role in animal immune defense. However, avian TCR studies have been limited to a few species, although their co-functional major histocompatibility complexes (MHCs) have been studied for decades, showing various copy numbers and polymorphisms. Here, using public genome data, we characterized the copy numbers, the phylogenic relationship and selection of T cell receptor complex (TCR-C) segments, and the genomic organization of TCR loci across birds. Various numbers of C segments were found in the TCRα/TCRδ, TCRβ, and TCRγ loci, and phylogenetic analysis reflected both ancient gene duplication events (two Cβ segments and Cδ segments divergent into CδI and CδII) and contemporary evolution (lineage-specific and species-specific characteristics). Most passerines lack CδII segments and a second TRD locus, except Meliphagidae and Maluridae. A relatively stable structure was verified in four TCR loci of birds, except for the arrangement of V segment groups. In this study, we explored the phylogenetic relationships of TCR-C segments across avians for the first time. We inferred gene duplication and loss events during the evolution process. The finding of diverse TCR germline repertoires provides a better understanding of the immune systems of birds.
所有有颌脊椎动物的胸腺衍生淋巴细胞都表达四种 T 细胞受体 (TCR) 链，它们在动物免疫防御中起着重要作用。然而，禽类 TCR 的研究仅限于少数几个物种，尽管它们的共功能主要组织相容性复合体 (MHC) 已经研究了几十年，显示出各种拷贝数和多态性。在这里，我们使用公共基因组数据，对鸟类 TCR 复合物 (TCR-C) 片段的拷贝数、系统发育关系和选择、TCR 基因座的基因组组织进行了特征描述。在 TCRα/TCRδ、TCRβ 和 TCRγ 基因座中发现了不同数量的 C 片段，系统发育分析反映了古老的基因复制事件（两个 Cβ 片段和 Cδ 片段分化为 CδI 和 CδII）和当代进化（谱系特异性和物种特异性特征）。除了蜂鸟科和阔嘴鸟科外，大多数雀形目鸟类缺乏 CδII 片段和第二个 TRD 基因座。除了 V 片段群的排列外，在鸟类的四个 TCR 基因座中验证了相对稳定的结构。在这项研究中，我们首次探索了禽类 TCR-C 片段的系统发育关系。我们推断了在进化过程中发生的基因复制和丢失事件。不同 TCR 胚系库的发现为更好地理解鸟类的免疫系统提供了依据。
