The Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China.
Mol Biol Rep. 2011 Oct;38(7):4483-90. doi: 10.1007/s11033-010-0578-0. Epub 2010 Dec 4.
Tumor necrosis factors receptor (TNFR) is a superfamily of proteins derived mainly from vertebrates. It plays significant role in diverse physiological and pathological events such as inflammation, apoptosis, autoimmunity and organogenesis. The gene of a new member of TNFR family, designated as CfTNFR2, was cloned and characterized from scallop, Chlamys farreri. The full-length cDNA of CfTNFR2 consisted of 1,501 nucleotides with a poly (A) tail, encoding a polypeptide of 378 amino acids with the estimated molecular mass of 42.70 kDa and predicted isoelectric point of 4.79. The characteristic motifs of the TNFR family proteins, such as three TNFR homology domains (also called CRD domains) and a death domain, were identified in CfTNFR2. Significantly, the deduced amino acid sequence of CfTNFR2 was closely homologous with mammalian osteoprotegerins showing approximately 37% identity. However, it shared only 11% amino acids identity with CfTNFR1, another TNFR homolog previously identified from the candidate scallop species, indicating that CfTNFR2 is a new molluscan TNFR protein. The spatial expression of CfTNFR2 in the tissues of the healthy and bacterial challenged scallops was detected by real-time PCR. CfTNFR2 mRNA was expressed constitutively in all selected tissues such as mantle, gill, gonad, hepatopancreas and hemocyte, among which gill and mantle displayed comparatively higher expression levels. Upon Listonella anguillarum challenge, CfTNFR2 expression was found to be remarkably up-regulated, especially in the tissues of gill (15.9-fold) and mantle (8.0-fold). The results reveal that CfTNFR2 is a constitutive and inducible acute-phase protein apparently involved in immune defense. The presence of CfTNFR2 (present study) and CfTNFR1 (previously identified from our lab) encouraged us to suggest that multiple members of TNFR family exist in mollusk, and the findings would help us to get better understanding on the evolutionary origin and functions of this protein family in mollusks.
肿瘤坏死因子受体 (TNFR) 是一个主要来源于脊椎动物的蛋白超家族。它在多种生理和病理事件中发挥重要作用，如炎症、细胞凋亡、自身免疫和器官发生。从扇贝 Chlamys farreri 中克隆并鉴定了 TNFR 家族的一个新成员 CfTNFR2 的基因。CfTNFR2 的全长 cDNA 由 1501 个核苷酸组成，带有 poly(A)尾巴，编码一个 378 个氨基酸的多肽，估计分子量为 42.70 kDa，预测等电点为 4.79。在 CfTNFR2 中鉴定到了 TNFR 家族蛋白的特征基序，如三个 TNFR 同源结构域（也称为 CRD 结构域）和一个死亡结构域。值得注意的是，CfTNFR2 的推导氨基酸序列与哺乳动物护骨素非常相似，同源性约为 37%。然而，它与之前从候选扇贝物种中鉴定到的另一个 TNFR 同源物 CfTNFR1 仅共享 11%的氨基酸同一性，表明 CfTNFR2 是一种新的软体动物 TNFR 蛋白。通过实时 PCR 检测 CfTNFR2 在健康和细菌感染的扇贝组织中的空间表达。CfTNFR2 mRNA 在所有选定的组织中如套膜、鳃、性腺、肝胰腺和血细胞中均呈组成型表达，其中鳃和套膜显示出相对较高的表达水平。在鳗弧菌攻毒后，发现 CfTNFR2 的表达显著上调，特别是在鳃（15.9 倍）和套膜（8.0 倍）组织中。结果表明 CfTNFR2 是一种组成型和诱导型急性期蛋白，显然参与免疫防御。CfTNFR2（本研究）和 CfTNFR1（之前从我们实验室鉴定）的存在促使我们提出 TNFR 家族的多个成员存在于软体动物中，并且这些发现将帮助我们更好地了解该蛋白家族在软体动物中的进化起源和功能。
