Department of Medicine, Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB, Canada.
Int J Immunogenet. 2012 Feb;39(1):55-67. doi: 10.1111/j.1744-313X.2011.01058.x. Epub 2011 Nov 18.
Interleukin-10 (IL-10) mediates its broad anti-inflammatory and immunoregulatory effects through two cell surface receptors by which binding to the IL-10 receptor 1 (IL-10R1) is the initial step that leads to recruitment of IL-10R2 and initiation of the ternary complex signal transduction cascade. The duck IL-10R1 (duIL-10R1) cDNA was obtained by using RT-PCR and 5'RACE. The deduced 574 amino acid protein has an amino acid identity of 62%, 27% and 28% with chicken, mouse and human IL-10R1, respectively. Comparison of the duIL-10R1 cDNA with duck genomic sequences revealed a seven exon-six intron structure of the duck IL-10R1 gene that shares a similar size with the respective exons 1-7 of the chicken and human IL-10R1 genes, but the avian genes are more compact. Promoter analysis identified putative binding sites for regulatory elements such as CCAAT enhancer binding protein-α, specificity protein 1 (Sp1), nuclear factor 1 (NF1), transcriptional regulatory protein Oct-1, nuclear factor (NF) κB and interferon-stimulated gene factor-3 (ISGF-3). A canonical TATA box was absent in proximity of the transcription initiation site, but a CpG island was present. Sequence analysis of the predicted duIL-10R1 protein revealed characteristic features of class-II cytokine receptors (CFR2) family members and a considerable degree of conservation of residues implicated in ligand binding across higher vertebrates. The predicted secondary structure of the duIL-10R1 extracellular domain is compatible with the two-subdomain structure of the human IL-10R1 protein established by its crystal structure. The 3D model structure shows conservation of the positions of conserved contact residues within four of the five ligand-binding loops. Within the cytoplasmic domain, residues implicated in signal transduction were conserved including two redundant peptide motifs GYXXQ essential for recruitment and activation of STAT3. DuIL-10R1 mRNA expression was most abundant in spleen, thymus, peripheral blood mononuclear cells (PBMCs) and lung. Mitogen stimulation of PBMCs transiently increased duIL-10R1 mRNA expression. Our observations suggest significant evolutionary conservation of the IL-10R1 genomic organization, protein structure and receptor function through the JAK/STAT signalling pathway across higher vertebrates.
白细胞介素-10（IL-10）通过两个细胞表面受体发挥其广泛的抗炎和免疫调节作用，与 IL-10 受体 1（IL-10R1）的结合是导致 IL-10R2 募集和启动三元复合物信号转导级联的初始步骤。通过 RT-PCR 和 5'RACE 获得了鸭 IL-10R1（duIL-10R1）cDNA。推导的 574 个氨基酸蛋白与鸡、鼠和人 IL-10R1 的氨基酸同一性分别为 62%、27%和 28%。duIL-10R1 cDNA 与鸭基因组序列的比较显示，鸭 IL-10R1 基因具有七个外显子-六个内含子结构，与鸡和人 IL-10R1 基因的相应外显子 1-7 大小相似，但禽类基因更为紧凑。启动子分析鉴定了调节元件的潜在结合位点，如 CCAAT 增强子结合蛋白-α、特异性蛋白 1（Sp1）、核因子 1（NF1）、转录调节蛋白 Oct-1、核因子（NF）κB 和干扰素刺激基因因子-3（ISGF-3）。在转录起始位点附近不存在典型的 TATA 盒，但存在 CpG 岛。duIL-10R1 蛋白预测的序列分析揭示了类 II 细胞因子受体（CFR2）家族成员的特征，并在较高等脊椎动物中保持了配体结合相关残基的相当程度的保守性。duIL-10R1 细胞外结构域的预测二级结构与通过其晶体结构建立的人 IL-10R1 蛋白的两个亚结构域结构兼容。3D 模型结构显示，在五个配体结合环中的四个环内保守接触残基的位置保持保守。在细胞质结构域中，包括对 STAT3 招募和激活至关重要的 GYXXQ 二肽基模在内的信号转导相关残基得到保守。duIL-10R1 mRNA 表达在脾脏、胸腺、外周血单核细胞（PBMCs）和肺中最为丰富。PBMCs 的有丝分裂原刺激短暂增加了 duIL-10R1 mRNA 表达。我们的观察结果表明，通过 JAK/STAT 信号通路，在较高等脊椎动物中，IL-10R1 基因组组织、蛋白质结构和受体功能都有显著的进化保守性。
