Randelli Elisa, Scapigliati Giuseppe, Buonocore Francesco
Department for Innovation in Biological, Agro-food and Forest systems, University of Tuscia, Largo dell'Università, 01100 Viterbo, Italy.
Results Immunol. 2011 Aug 30;1(1):31-5. doi: 10.1016/j.rinim.2011.08.003. eCollection 2011.
The CD3 complex is the common marker on the surface of both αβ and γδ T cells and is essential for formation of the T-cell receptor complex and for T-cell activation. In this paper, we report the gene cloning and molecular characterization of a CD3γ/δ homologue in sea bass (Dicentrarchus labrax), the analysis of transcription levels in lymphoid and non-lymphoid organs and the gene regulation after in vitro stimulation with LPS and PHA. Four cysteine residues in the extracellular domain, involved in the constitution of immunoglobulin-like domain, are present in sea bass CD3γ/δ sequence and they are conserved both in number and position from mammals to teleost sequences. Similar to other known CD3γ/δs, in sea bass CD3γ/δ there is also a conserved immunoreceptor tyrosine-based activation ITAM motif that could be responsible for its individual signal transduction capacity. The real time RT-PCR basal analysis shows the highest level of CD3γ/δ mRNA in thymus, followed by peripheral blood leucocytes, spleen, gills, gut, liver, head kidney, brain and muscle. The expression analysis under stimuli condition reveals a significant decrease of CD3γ/δ expression after LPS stimulation and a significant increase after PHA-L stimulation, in agreement with mammals results. In conclusion, these data allow us to affirm that sea bass CD3γ/δ can be used as a T cell marker and will help in adding new insight on the immune response mechanisms of sea bass.
CD3复合体是αβ和γδ T细胞表面的共同标志物，对于T细胞受体复合体的形成和T细胞激活至关重要。在本文中，我们报道了海鲈（欧洲鲈）中CD3γ/δ同源物的基因克隆和分子特征，分析了其在淋巴和非淋巴器官中的转录水平以及经脂多糖（LPS）和植物血凝素（PHA）体外刺激后的基因调控。海鲈CD3γ/δ序列的胞外结构域中有四个半胱氨酸残基，参与免疫球蛋白样结构域的构成，从哺乳动物到硬骨鱼序列，它们在数量和位置上都是保守的。与其他已知的CD3γ/δ类似，海鲈CD3γ/δ中也有一个保守的基于免疫受体酪氨酸的激活基序（ITAM），可能负责其个体信号转导能力。实时RT-PCR基础分析显示，CD3γ/δ mRNA在胸腺中的水平最高，其次是外周血白细胞、脾脏、鳃、肠道、肝脏、头肾、脑和肌肉。刺激条件下的表达分析表明，LPS刺激后CD3γ/δ表达显著下降，PHA-L刺激后显著增加，这与哺乳动物的结果一致。总之，这些数据使我们能够确定海鲈CD3γ/δ可作为T细胞标志物，并将有助于深入了解海鲈的免疫反应机制。
