Molecular cloning and characterization of SOCS-2 from Manila clam Ruditapes philippinarum

Suppressor of cytokine signaling (SOCS) family members are key regulators of immunological homeostasis. In this study, we have discovered the SOCS-2 member from Manila clam Ruditapes philippinarum and further analyzed its immune responses against lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid (poly I:C). Amino acid sequence of RpSOCS-2 consists of cytokine inducible SRC homology 2 (SH2) and SOCS box domains similar to vertebrate SOCS counterparts. It has the highest amino acid identity (41%) with Pacific oyster (Crassostrea gigas) SOCS-2 and showed close evolutional relationship with disk abalone (Haliotis discus discus) SOCS-2. Tissue specific expression results showed that RpSOCS-2 was constitutively expressed in all examined tissues with the highest level in gill tissue of un-challenged clams. RpSOCS-2 mRNA expression was up-regulated by LPS and poly I:C challenge in gills. Discovery of RpSOCS-2 homologue and expression analysis would support for understanding evolutional relationships and their role in innate immune responses in mollusks, respectively.