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Molluscan death effector domain (DED)-containing caspase-8 gene from disk abalone (Haliotis discus discus): Molecular characterization and expression analysis

Lee, Youngdeuk, De Zoysa, Mahanama, Whang, Ilson, Lee, Sukkyoung, Kim, Yucheol, Oh, Chulhong, Choi, Cheol Young, Yeo, Sang-Yeob, Lee, Jehee
Fish & shellfish immunology 2011 v.30 no.2 pp. 480-487
Haliotis discus, Listeria monocytogenes, Tubifex tubifex, Vibrio alginolyticus, Vibrio parahaemolyticus, Viral hemorrhagic septicemia virus, abalone, active sites, amino acid sequences, apoptosis, bacteria, caspase-8, cysteine, death, gene expression, genes, gills, hemocytes, immune response, isoelectric point, messenger RNA, molecular cloning, molecular weight, open reading frames, phylogeny, reverse transcriptase polymerase chain reaction, sludge
The caspase family represents aspartate-specific cysteine proteases that play key roles in apoptosis and immune signaling. In this study, we cloned the first death effector domain (DED)-containing molluscan caspase-8 gene from disk abalone (Haliotis discus discus), which is named as hdCaspase-8. The full-length hdCaspase was 2855 bp, with a 1908 bp open reading frame encoding 636 amino acids. The hdCaspase-8 had 72 kDa predicted molecular mass with an estimated isoelectric point (PI) of 6.0. The hdCaspase-8 amino acid sequence contained the characteristic feature of an N-terminal two DED, a C-terminal catalytic domain and the caspase family cysteine active site ⁵¹³KPKLFFLQACQG⁵²⁴. Phylogenetic analysis results showed that hdCaspase-8 is more similar to the invertebrate Tubifex tubifex (sludge worm) caspase-8. Real-time RT-PCR results showed that hdCaspase-8 constitutively and ubiquitously expressed in all tested tissue of unchallenged disk abalone. The basal expression level of hdCaspase-8 in gill tissue was higher than all other tested tissues. The hdCaspase-8 mRNA expression in gill and hemocytes was significantly up-regulated by exposure to bacteria (Vibrio alginolyticus, Vibrio parahemolyticus and Listeria monocytogenes) and VHSV (viral hemorrhagic septicemia virus), as compared to control animals. These results suggest that hdCaspase-8 may be involved in immune response reactions in disk abalone.