Huang Baoyu, Zhang Linlin, Du Yishuai, Li Li, Qu Tao, Meng Jie, Zhang Guofan
Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao, 266071, China.
Mol Biol Rep. 2014 Oct;41(10):6481-91. doi: 10.1007/s11033-014-3531-9. Epub 2014 Jul 11.
Diverse alternative splicing isoforms play an important role in immune diversity and specificity. Their role in molluscan host-defense is however poorly understood. We characterized two alternative isoforms of tumor necrosis factor receptor-associated factor 3 (TRAF3) in the Pacific oyster, Crassostrea gigas, which were named CgTRAF3-S and CgTRAF3-L. An intron was retained in CgTRAF3-L, introducing a premature termination codon. Comparison and phylogenetic analysis revealed that CgTRAF3 shared a higher identity with other species, suggesting the conservation of the two gene transcripts. Quantitative real-time PCR was performed and the expression levels of CgTRAF3 isoforms were found to be significantly changed after Vibrio anguillarum and ostreid herpesvirus 1 challenges. These two isoforms represented contrary trends, indicating that CgTRAF3-L might function as a negative regulator of CgTRAF3-S. We also investigated the expression level of the transcripts of the two CgTRAF3 isoforms, following the silence of C. gigas mitochondrial anti-viral signaling protein like gene (CgMAVS-like). We concluded that CgTRAF3 might be involved in a MAVS-mediated immune signaling pathway. This study suggests that CgTRAF3 may be a response to bacterial and viral stimulation and that the two isoforms may be involved in immune response pathways. It is also possible that the two alternative splicing isoforms could be inter-coordinated and may promote survival of these oysters under immune stress conditions.
多种可变剪接异构体在免疫多样性和特异性中发挥着重要作用。然而，它们在软体动物宿主防御中的作用却知之甚少。我们鉴定了太平洋牡蛎（Crassostrea gigas）中肿瘤坏死因子受体相关因子3（TRAF3）的两种可变异构体，分别命名为CgTRAF3-S和CgTRAF3-L。CgTRAF3-L中保留了一个内含子，引入了一个提前终止密码子。比较和系统发育分析表明，CgTRAF3与其他物种具有较高的同源性，这表明这两种基因转录本具有保守性。进行了定量实时PCR，发现鳗弧菌和牡蛎疱疹病毒1攻击后，CgTRAF3异构体的表达水平发生了显著变化。这两种异构体呈现相反的趋势，表明CgTRAF3-L可能作为CgTRAF3-S的负调节因子发挥作用。我们还研究了在太平洋牡蛎线粒体抗病毒信号蛋白样基因（CgMAVS-like）沉默后，这两种CgTRAF3异构体转录本的表达水平。我们得出结论，CgTRAF3可能参与了MAVS介导的免疫信号通路。这项研究表明，CgTRAF3可能是对细菌和病毒刺激的一种反应，并且这两种异构体可能参与免疫反应途径。这两种可变剪接异构体也有可能相互协调，并可能促进这些牡蛎在免疫应激条件下的存活。
