title: Identification and functional characterization of two executioner caspases in Crassostrea gigas.
abstract: Caspase-3 and caspase-7 are two key effector caspases that play important roles in apoptotic pathways that maintain normal tissue and organ development and homeostasis. However, little is known about the sequence, structure, activity, and function of effector caspases upon apoptosis in mollusks, especially marine bivalves. In this study, we investigated the possible roles of two executioner caspases in the regulation of apoptosis in the Pacific oyster Crassostrea gigas. A full-length caspase-3-like gene named Cgcaspase-3 was cloned from C.gigas cDNA, encoding a predicted protein containing caspase family p20 and p10 domain profiles and a conserved caspase active site motif. Phylogenetic analysis demonstrated that both Cgcaspase-3 and Cgcaspase-1 may function as effector caspases clustered in the invertebrate branch. Although the sequence identities between the two caspases was low, both enzymes possessed executioner caspase activity and were capable of inducing cell death. These results suggested that Cgcaspase-3 and Cgcaspase-1 were two effector caspases in C. gigas. We also observed that nucleus-localized Cgcaspase-3, may function as a caspase-3-like protein and cytoplasm-localized Cgcaspase-1 may function as a caspase-7-like protein. Both Cgcaspase-3 and Cgcaspase-1 mRNA expression increased after larvae settled on the substratum, suggesting that both caspases acted in several tissues or organs that degenerated after oyster larvae settlement. The highest caspase expression levels were observed in the gills indicating that both effector caspases were likely involved in immune or metabolic processes in C. gigas.
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Qu
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China ; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Baoyu
authors.initials: B
authors.lastname: Huang
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Xu
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China ; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Huang
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China ; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Li
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Yishuai
authors.initials: Y
authors.lastname: Du
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Guofan
authors.initials: G
authors.lastname: Zhang
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D053179:Caspase 7 / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D049896:Crassostrea / Q000145:classification / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005880:Gills / Q000201:enzymology / Q000254:growth & development; D057809:HEK293 Cells; D006801:Humans; D007814:Larva / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D010802:Phylogeny; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D011994:Recombinant Proteins; D053148:Caspase 3; D053179:Caspase 7