Functional Research Of Syntenin In Anti-bacterial And Anti-viral Immune Response Of Kuruma Shrimp Marsupenaeus Japonicus

Mariculture organisms are important sources of human food. Among them, kuruma shrimp Marsupenaeus japonicus is an important aquaculture industry species. However, the shrimp aquaculture industry suffered the diseases that caused by bacteria and virus in the past decade. Study on the innate immunity system of shrimp will provide both theoretical and practical support to this industry. As the smallest living system, cell relies on various proteins to organize life activities in order. Among them, adaptor proteins play a significant role in connection and transport. The functional study of adaptor proteins in shrimp will help to understand the mechanism of innate immunity better.Syntenin is a multifunctional cytosolic adaptor protein, contributing to cell migration, proliferation, attachment and apoptosis, as well as immune response to virus in vertebrate. However, the function of syntenin in the anti-bacteria and anti-virus response of invertebrate remains unclear. In this study, we identified a syntenin-like gene (MjSyn) from the kuruma shrimp (Marsupenaeus japonicus), detected its function in the immunity of shrimp. The full-length MjSyn was 1223 bp with a 963 bp open reading frame encoding 320 amino acids. The deduced MjSyn proteins contained two atypical PDZ domains (sequence repeat that firstly reported in postsynaptic density protein or PSD-95, DlgA and ZO-1 protein), an N-terminal domain and a C-terminal domain. Reverse transcription PCR showed that MjSyn was expressed in all tested tissues. Quantitative real-time RT-PCR analysis revealed that MjSyn transcripts in hemocyte, gill and intestine were significantly induced at various time points after infection with Staphylococcus aureus, Vibrio anguillarum and white spot syndrome virus (WSSV). Knockdown the expression of MjSyn by RNA interference led to significant decrease of phagocytic ability and increased bacteria number in vivo of shrimp. Moreover, the expression of MjCnx, a cytoplasma and membrane location lectin chaperone protein was inhibited in the MjSyn knock down shrimp, indicated a possible calnexin related way. Taken together, MjSyn participating in the bacteria clearance response of kuruma shrimp provides a new insight into the function of this kind of important adaptor protein.At the same time, we found that the replication of WSSV in shrimp decreased when MjSyn was knocked down, while over-expression of MjSyn led to an increasing expression of VP28. Pull-down assay in vitro showed that full-length MjSyn and truncated PDZ1+2 and CTD could bind to the envelope proteins VP24, VP26 and VP28, indicating a role of anti-viral immune activity via binding to virus envelop proteins. In addition, MjSyn in cytoplasm clustered onto the cell membrane and distributed in polarization when challenged with WSSV. The F-actin movement tendency was collaborate with MjSyn, indicating a connection between MjSyn and F-actin in response to WSSV infection. It is worth noting that secreted MjSyn and VP28 can be detected in hemolymph after WSSV challenge. In summary, our results provide novel evidence that MjSyn plays an important role in shrimp innate immune system.