Characterization and expression analysis of a caspase-2 in an invertebrate echinoderm sea cumber Apostichopus japonicus

Molecular cloning and characterization of four caspases members in Apostichopus japonicus

“…5). Ye et al [22] study indicated that their Ajcaspase-2 transcript was significantly decreased about 66.9% at 12 h post LPS injection and reached the peak expression at 24 h when compared with PBS injection, which was different from our results. Caspase-2 is an initiator caspase which can cleave the pro-apoptotic Bcl-2 family members and result in release of cytochrome c from the mitochondria to induce apoptosis, and it is also participate in nonapoptotic processes including DNA repair, lipid biosynthesis, and regulation of oxidative stress [19,46].…”

“…They were both highest expressed in intestine, followed by coelomocytes, respiratory tree and tentacle. This expression pattern was similar to that of another caspase-2 gene in A. japonicus, in which the higher expression levels were observed in coelomocytes, respiratory tree and intestine [22]. Sea cucumbers possess branching tentacles mainly used to filter water column, where as an important site of entry of pathogens [44].…”

“…The Ajcaspase-2 and Ajcaspase-8 both exhibited typical initiator caspase domain architectures containing a CARD (residues 1e89) domain in the deduced amino acid of Ajcaspase-2, and a DED (residues 7e83) domain in the N-terminal of Ajcaspase-8, respectively. The deduced amino acid of Ajcaspase-2 shared only 43.9% homology with the identified Ajcaspase-2 by Ye et al, [22]. Besides, a similar DED domain (residues 11e93) was also found in the effector caspase of Ajcaspase-3 with two internal repeat domains (residues 166e190 and residues 193e217) in this amino acid sequence.…”

“…Although caspase-2 shares some substrate specificity with the executioner caspases [19], in many respects, it is also considered as an initiator caspase, and activate downstream molecules of caspase-3 and caspase-6 [20]. For instance, caspase-2 gene has been identified from marine invertebrates Pacific oyster Crassostrea gigas and sea cucumber Apostichopus japonicus after pathogens or LPS infection [21,22], and their roles in immune defense are well indicated.…”

“…In our previous work, we founded that LPS challenge A. japonicus could significantly induced coelomocyte apoptosis in vitro [31,32], suggesting that caspase genes might play importantly roles in apoptotic signal pathways. To date, only caspase-2 gene has been characterized in sea cucumber which involve in immune defense after LPS injection [22]. To further understand the regulation of apoptotic signal pathways involved in the immune response of sea cucumber, in this study, we cloned multiple caspase genes including two effector caspases and two initiator caspases and characterized their various expression profiles towards Vibrio splendidus challenge.…”