Tran Ngoc Tuan, Jakovlić Ivan, Wang Wei-Min
Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, College of Fisheries, Huazhong Agricultural University, Wuhan 430070, Hubei, People's Republic of China.
J Genet. 2017 Sep;96(4):613-623. doi: 10.1007/s12041-017-0816-5.
Smac/DIABLO gene is essential for the apoptosis mechanism in mammals. This study is the first report of the Megalobrama amblycephala (ma) diablo gene, and the first report of the tertiary structure of a Diablo polypeptide in fish. Madiablo is 1540-bp long with an open reading frame of 792 bp, encoding a putative protein of 263 amino acids with a molecular weight of 29.2 kDa. Phylogenetic analysis indicates that it is closely related to the zebrafish Diablo-a homologue. It also indicates the existence of two diablo copies (a and b) in teleosts; apart fromthe Percomorpha group,where diablo-b has been lost, but diablo-a had undergone an independent duplication. Madiablo protein contains a long Smac_DIABLO super family domain (Leu32-Asp263) and alpha helices were prevalent in the secondary structure. Homology model of madiablo protein was constructed using the comparative modelling method. Expression of madiablo mRNA transcript was investigated using qPCR: (i) in five tissues from a healthy blunt snout bream, indicating the highest constitutive expression level in liver. (ii) During the embryo and juvenile development, indicating a spike in expression during hatching and in later phases of the juvenile development. (iii) In response to Aeromonas hydrophila infection, indicating the downregulation in liver, spleen and kidney during the first 12 h postinfection and upregulation in spleen and kidney after 24 h postinfection (hpi). The results imply that madiablo is homologous to Diablo orthologues in other species, both structurally and functionally, and that, it probably plays a role in the immune system of M. amblycephala.
Smac/DIABLO基因对哺乳动物的细胞凋亡机制至关重要。本研究首次报道了团头鲂（ma）的暗黑破坏神基因，也是鱼类中暗黑破坏神多肽三级结构的首次报道。团头鲂暗黑破坏神基因长1540 bp，开放阅读框为792 bp，编码一个推定的263个氨基酸的蛋白质，分子量为29.2 kDa。系统发育分析表明，它与斑马鱼暗黑破坏神同源物密切相关。这也表明硬骨鱼中存在两个暗黑破坏神基因拷贝（a和b）；除鲈形目外，暗黑破坏神基因b已丢失，但暗黑破坏神基因a发生了独立复制。团头鲂暗黑破坏神蛋白包含一个长的Smac_DIABLO超家族结构域（Leu32-Asp263），二级结构中α螺旋普遍存在。采用比较建模方法构建了团头鲂暗黑破坏神蛋白的同源模型。使用qPCR研究了团头鲂暗黑破坏神基因mRNA转录本的表达：（i）在健康团头鲂的五个组织中，表明在肝脏中的组成型表达水平最高。（ii）在胚胎和幼鱼发育过程中，表明在孵化期和幼鱼发育后期表达量激增。（iii）响应嗜水气单胞菌感染，表明感染后12小时内肝脏、脾脏和肾脏中的表达下调，感染后24小时（hpi）后脾脏和肾脏中的表达上调。结果表明，团头鲂暗黑破坏神基因在结构和功能上与其他物种的暗黑破坏神直系同源物同源，并且它可能在团头鲂的免疫系统中发挥作用。
