cDNA cloning and characterization of a new member of the tumor necrosis factor receptor family gene from scallop, Chlamys farreri Jianguo Su • Limei Qiu • Ling li • Lin Liu • Lingling Wang • Vinu S. Siva • Dahui Yu • Linsheng Song Received: 9 March 2010 / Accepted: 20 November 2010 / Published online: 4 December 2010 Ó Springer Science+Business Media B.V. 2010 Abstract Tumor necrosis factors receptor (TNFR) is a superfamily of proteins derived mainly from vertebrates. It plays significant role in diverse physiological and patho- logical events such as inflammation, apoptosis, autoim- munity 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 expres- sed 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. Keywords TNFR Á Osteoprotegerins (OPGs) Á Chlamys farreri Á cDNA cloning Introduction Tumor necrosis factor (TNF) and TNF receptor (TNFR) family members play pivotal role in diverse biological processes, such as host defense, inflammation, apoptosis, autoimmunity, development and organogenesis of the immune system [1, 2]. To date, at least 18 TNF family ligands and 29 receptors have been identified in human [3]. The interaction between TNF and TNFR is rather highly specific, and obviously the number of TNFRs is shown to be greater than that of TNFs, signifying the key regulatory role of the TNFRs in transducing the extrinsic TNF superfamily signals to various functional targets [3]. J. Su Á L. Qiu (&) Á L. li Á L. Liu Á L. Wang Á V. S. Siva Á L. Song (&) The Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China e-mail: qiulimei@ms.qdio.ac.cn L. Song e-mail: lshsong@ms.qdio.ac.cn J. Su College of Animal Science and Technology, Northwest A and F University, Yangling 712100, China D. Yu South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangdong 510300, China 123 Mol Biol Rep (2011) 38:4483–4490 DOI 10.1007/s11033-010-0578-0