Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China; National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China.
Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Dev Comp Immunol. 2021 Jan;114:103791. doi: 10.1016/j.dci.2020.103791. Epub 2020 Aug 9.
CD3 is an essential component of the TCR-CD3 complex which plays a key role in adaptive immunity. Non-mammalian CD3 complex consists of CD3γ/δ, CD3ε and CD3ζ subunits. In this study, homologues of CD3γ/δ and CD3ε (termed CiCD3γ/δ and CiCD3ε) have been identified in grass carp (Ctenopharyngodon idella). Like their counterparts from other vertebrates, the CiCD3γ/δ and CiCD3ε are clustered in the same locus in the genome and encode proteins which are structurally conserved, comprising a signal peptide, an extracellular domain, a transmembrane domain and a cytoplasmic tail containing two ITAM motifs. Sequence analyses identified two novel conserved motifs in the cytoplasmic tail of CiCD3γ/δ and CiCD3ε, one is composed of an arginine and lysine motif (RK or RR) at the C terminus of CiCD3γ/δ and a proline rich domain (PxxPxP/Q) located at the N terminus of ITAM motifs of CiCD3ε. Both genes were highly expressed at the mRNA level in the spleen and gills of healthy fish and could be modulated by infection of Flavobacterium columnare and grass carp reovirus. A monoclonal antibody against the CiCD3γ/δ (GC38T) was produced and showed good reactivity with the native molecule in Western blotting analysis and flow cytometry. The CiCD3γ/δ cells were analysed in the primary leucocytes, accounting for 5.5% of lymphocytes isolated from spleen, 4.5% from head kidney and 2.8% from peripheral blood. The CiCD3γ/δ cells were localized in the gills and head kidney by fluorescent confocal microscopy.
CD3 是 TCR-CD3 复合物的一个必需组成部分，在适应性免疫中起着关键作用。非哺乳动物的 CD3 复合物由 CD3γ/δ、CD3ε 和 CD3ζ 亚基组成。在这项研究中，草鱼（Ctenopharyngodon idella）的 CD3γ/δ 和 CD3ε 的同源物（称为 CiCD3γ/δ 和 CiCD3ε）已被鉴定出来。与来自其他脊椎动物的对应物一样，CiCD3γ/δ 和 CiCD3ε 在基因组中聚集在同一个基因座，并编码结构保守的蛋白质，包括一个信号肽、一个细胞外结构域、一个跨膜结构域和一个含有两个 ITAM 基序的细胞质尾巴。序列分析确定了 CiCD3γ/δ 和 CiCD3ε 细胞质尾巴中的两个新的保守基序，一个是 CiCD3γ/δ C 末端的精氨酸和赖氨酸基序（RK 或 RR），另一个是位于 ITAM 基序 N 末端的富含脯氨酸的结构域（PxxPxP/Q）。在健康鱼类的脾脏和鳃中，这两个基因在 mRNA 水平上都有高表达，并能被柱状黄杆菌和草鱼呼肠孤病毒的感染所调节。制备了针对 CiCD3γ/δ 的单克隆抗体（GC38T），并在 Western blot 分析和流式细胞术分析中显示出与天然分子的良好反应性。在初级白细胞中分析 CiCD3γ/δ 细胞，占从脾脏分离的淋巴细胞的 5.5%，从头肾分离的淋巴细胞的 4.5%，从外周血分离的淋巴细胞的 2.8%。通过荧光共聚焦显微镜观察 CiCD3γ/δ 细胞定位于鳃和头肾。
