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A novel effector caspase (Caspase-3/7-1) involved in the regulation of immune homeostasis in Chinese mitten crab Eriocheir sinensis

Qu, Chen, Yang, Wen, Xu, Qingsong, Sun, Jiejie, Lu, Mengmeng, Wang, Ying, Liu, Chao, Wang, Weilin, Wang, Lingling, Song, Linsheng
Fish & shellfish immunology 2018 v.83 pp. 76-83
Aeromonas hydrophila, Eriocheir sinensis, active sites, apoptosis, aspartic acid, caspases, complementary DNA, cytoplasm, fish, gene expression, gene expression regulation, hemocytes, hepatopancreas, homeostasis, hydrogen peroxide, immunology, lipopolysaccharides, membrane glycoproteins, messenger RNA, open reading frames, polypeptides, shellfish, tissues
Caspases are a conserved family of cysteine proteases characterized by specificity for aspartic acid and play an essential role in cell apoptosis. In the present study, a novel effector caspase (designated as EsCaspase-3/7-1) was identified from Chinese mitten crab Eriocheir sinensis. The open reading frame of EsCaspase-3/7-1 cDNA was of 972 bp, encoding a polypeptide of 323 amino acids. EsCaspase-3/7-1 contained an N-terminal prodomain and a conservative C-terminal CASc domain, with the conserved active site “QACRG”. The mRNA transcripts of EsCaspase-3/7-1 were constitutively expressed in all the examined tissues with high expression level in hemocytes, hepatopancreas and gill. The EsCaspase-3/7-1 protein was mainly distributed in the cytoplasm of hemocytes. After Aeromonas hydrophila and lipopolysaccharide (LPS) stimulations, the mRNA expression level of EsCaspase-3/7-1 in hemocytes increased significantly. The mRNA expression level of EsCaspase-3/7-1 in hemocytes was significantly up-regulated after H2O2 treatment in vitro. The recombinant EsCaspase-3/7-1 protein (rEsCaspase-3/7-1) was capable of hydrolyzing the substrate Ac-DEVD-pNA rather than Ac-YVAD-pNA and Ac-VEID-pNA in vitro, and exhibited binding activity to LPS. These results demonstrated that EsCaspase-3/7-1 might act as an LPS receptor, and play an important role in the regulation of immune homeostasis of E. sinensis.