Characterization and functional analysis of a caspase 3 gene: Evidence that ChCas 3 participates in the regulation of apoptosis in Crassostrea hongkongensis

Phylogenetic analysis of the caspase family in bivalves: implications for programmed cell death, immune response and development

“…V. splendidus also increased caspase-3 activity in the posterior adductor muscle in M. galloprovincialis 24-72 h post injection (84). Furthermore, Vibrio alginolyticus increases the expression of Ch8A and Ch3/7 in haemocytes of C. hongkongensis oysters (25,31). Interestingly, the same Vibrio sp.…”

“…Several caspases have been identi ed in bivalve species with homologs to caspase-8 (21-25), caspase-2 (22,26,27), caspase-1 (27,28), caspase-3 (26,(29)(30)(31)(32), caspase-6 (32) and a potential bivalve speci c group of caspase-3/7 (22,33). Most of these bivalve caspases were assumed to be involved in apoptotic processes in relation to haemocytes responses to pathogen infections (21,22,25,28,29,31,(34)(35)(36), environmental stressors (22,24,32,33,36) or developmental processes (26,30). While caspase-related pyroptosis has not been investigated in bivalves, caspase-1 mediated pyroptosis has been suggested in other invertebrates such as sea cucumbers (37) and crustaceans (38).…”

“…To examine the caspase family in bivalves, we investigated the presence of caspase homologs using a combination of bioinformatics and phylogenetic analyses. We blasted the C. gigas genome for caspase homologs and identi ed 35 potential homologs in the addition to the already cloned caspases in C. gigas (21,(27)(28)(29)(30)33), Crassostrea angulata (26), Crassostrea hongkongensis (25,31), M. galloprovincialis (22,24), Mytilus coruscus (24), Mytilus californianus (23) and Tegillarca granosa (32). Phylogenetic analyses of these bivalve caspases, as compared to homologs in other invertebrates and vertebrate species, con rmed expansions of the initiator and executioner caspase groups while also suggesting a need to correct some of the identi cations of previously classi ed caspases.…”

“…Thirty-ve new putative caspases have been identi ed in the Paci c oyster genome in addition to the twenty-three caspase homologs previously characterised in bivalve species (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33). All identi ed bivalve caspases possess a large p20 caspase subunit unique for caspase homologues.…”

“…Spatial expression studies of caspases in mussels and oysters have shown that initiator and executioner caspases are frequently expressed in haemocytes as well as gills, digestive glands and labial pals, which are areas exposed to pathogens and environmental stressors (i.e. pollutants) (21,22,28,30,31,81). Moreover, our identi cation of a large number of different bivalve caspases with unique traits and motifs such as lack of second DED, or additional DDs and DSRMs in prodomains, or variations in p20 active sites, provides insight into the regulatory mechanism of apoptosis.…”