Guan Zheng-Bing, Shui Yan, Zhang Shuang-Quan
Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, Life Sciences College, Nanjing Normal University, Nanjing 210046, PR China.
Cytokine. 2007 Sep;39(3):192-200. doi: 10.1016/j.cyto.2007.07.190. Epub 2007 Sep 5.
B-cell activating factor belonging to the TNF family (BAFF) and a proliferation-inducing ligand (APRIL) are two related members of the TNF ligand superfamily. These two ligands and their receptors, also termed "the BAFF/APRIL system", play important immunological roles, especially in the B-cell arm of the immune system. This paper reports the cloning and expression analysis of these two cytokines in rabbit (Oryctolagus cuniculus) by homology cloning. The complete transcript of the rabbit BAFF was sequenced and contained 1457 bp, including an 873 bp open reading frame. The predicted protein of 290 aa revealed the presence of the BAFF family signature, the "Flap". The soluble mature part of rabbit BAFF (sBAFF) showed 75-92% sequence identity with mammalian and avian homologs. The full-length cDNA of rabbit APRIL contained 1030 bp of which 753 bp are the open reading frame. The conserved potential N-glycosylation site and the cysteine residues were found in both the two ligands. The predicted three dimensional (3D) structures of sBAFF and sAPRIL analyzed by comparative protein modeling reveal that they are very similar to the human counterparts. Real-time PCR analysis revealed that rabbit BAFF gene was predominantly expressed in the lymphoid tissues, such as spleen and thymus; while the APRIL mRNA was found to be relatively high in a wide range of tissues. These findings indicate that BAFF and APRIL in rabbit play similar roles as in human. It provides the basis for investigation on their roles in regulating B-cell development and immune responses in rabbit and also contributes to our understanding of the evolution of these two novel TNF ligands.
肿瘤坏死因子家族的B细胞激活因子（BAFF）和增殖诱导配体（APRIL）是肿瘤坏死因子配体超家族的两个相关成员。这两种配体及其受体，也被称为“BAFF/APRIL系统”，发挥着重要的免疫作用，尤其是在免疫系统的B细胞分支中。本文通过同源克隆报道了这两种细胞因子在兔（穴兔）中的克隆及表达分析。兔BAFF的完整转录本经测序，包含1457bp，其中包括一个873bp的开放阅读框。预测的290个氨基酸的蛋白质显示存在BAFF家族特征结构“Flap”。兔BAFF的可溶性成熟部分（sBAFF）与哺乳动物和鸟类同源物的序列同一性为75%-92%。兔APRIL的全长cDNA包含1030bp，其中753bp为开放阅读框。在这两种配体中均发现了保守的潜在N-糖基化位点和半胱氨酸残基。通过比较蛋白质建模分析的sBAFF和sAPRIL的预测三维（3D）结构表明，它们与人类对应物非常相似。实时PCR分析表明，兔BAFF基因主要在脾脏和胸腺等淋巴组织中表达；而APRIL mRNA在多种组织中相对较高。这些发现表明，兔中的BAFF和APRIL与人类中的发挥相似作用。这为研究它们在调节兔B细胞发育和免疫反应中的作用提供了基础，也有助于我们理解这两种新型肿瘤坏死因子配体的进化。
