title: Cloning and characterization of a novel caspase-8-like gene in Crassostrea gigas.
abstract: Cysteine-dependent aspartate-directed proteases, or caspases, play key roles in apoptosis and immune defense. In this study, we cloned the first caspase-8-like gene (CgCaspase8-2) identified in the pacific oyster, Crassostrea gigas. The 2572-bp cDNA encodes a putative protein of 714 amino acids that contains two tandem death effector domains (DEDs) at the N-terminal, and P20 and P10 domains at the C-terminal. The conserved pentapeptide motif QACQG was also identified in the deduced CgCaspase8-2 protein. Phylogenetic analysis indicated that CgCaspase8-2 was clustered with initiator caspases in the invertebrate subgroup, but the similarity between CgCaspase8-2 and other invertebrate caspase-8s was low. CgCaspase8-2 protein was localized in the cytoplasm, and over-expression of CgCaspase8-2 in HEK293T cells induced cell death, suggesting a role in apoptosis. Quantitative real-time PCR results demonstrated that CgCaspase8-2 was widely expressed in various tissues and developmental stages, with the highest CgCaspase8-2 expression levels detected in hemolymph and the blastula stage. Furthermore, CgCaspase8-2 transcripts showed no change in response to a bacterial challenge but exhibited notable up-regulation post-poly (I:C) challenge, suggesting that CgCaspase8-2 is specifically involved in immune responses against viruses. In summary, CgCaspase8-2 is involved in both apoptotic and immune function.
authors.affiliation: National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Li
authors.affiliation: National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Qu
authors.affiliation: National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Baoyu
authors.initials: B
authors.lastname: Huang
authors.affiliation: National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Peng
authors.initials: P
authors.lastname: Ji
authors.affiliation: National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Wen
authors.initials: W
authors.lastname: Huang
authors.affiliation: National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China.
authors.forename: Huayong
authors.initials: H
authors.lastname: Que
authors.affiliation: National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China. Electronic address: lili@qdio.ac.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China. Electronic address: gfzhang@qdio.ac.cn.
authors.forename: Guofan
authors.initials: G
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D053181:Caspase 8 / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D002470:Cell Survival; D003001:Cloning, Molecular; D049896:Crassostrea / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D011070:Poly I-C / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014735:Vibrio Infections / Q000235:genetics / Q000276:immunology; D044149:Vibrio alginolyticus
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D053181:Caspase 8; D011070:Poly I-C
keywords: Apoptosis; CgCaspase8-2; Crassostrea gigas; Immune response