A SPRY domain-containing SOCS box protein 3 (SPSB3) involved in the regulation of cytokine production in granulocytes of Crassostrea gigas

Abstract The sp1A/ryanodine receptor (SPRY) family members have been reported to involve in important biological pathways, including innate immune signaling, cytokine signaling suppression, development, cell growth, and retroviral restriction. In the present study, a SPRY domain-containing SOCS box protein (named as Cg SPSB3) was identified and characterized from oyster Crassostrea gigas . The open reading frame of Cg SPSB3 gene was of 699 bp, encoding a polypeptide of 232 amino acid residues with a central SPRY domain and a C-terminal SOCS box motif. Cg SPSB3 mRNA transcripts could be detected in all the examined tissues with the highest level in hemocytes, which was about 82.72-fold ( p Cg SPSB3 mRNA in granulocytes was significantly higher than that in semi-granulocytes and agranulocytes, which was about 2.04-fold ( p Cg SPSB3 protein was mainly distributed in the cytoplasm of granulocytes. The mRNA expression of Cg SPSB3 in hemocytes was up-regulated after lipopolysaccharide (LPS) and Vibrio splendidus stimulations. The mRNA expression of Cg IFNLP, Cg IL17-5 and Cg TNF-1 decreased significantly ( p Cg SPSB3 mRNA was knocked down by RNAi. These results collectively indicated that Cg SPSB3 might play an important role in regulating cytokines production in granulocytes of C. gigas .