Functional Analysis Of Calnexin In Antibacterial Immunity Of Marsupenaeus Japonicus

Calnexin (Cnx) is an endoplasmic reticulum (ER) membrane—bound lectin chaperone that comprises a dedicated maturation system with another lectin chaperone calreticulin (Crt). This maturation system is known as the Cnx/Crt cycle. The main functions of Cnx are Ca2+storage, glycoprotein folding, and quality control of synthesis. Recent studies have shown that Cnx is important in phagocytosis and in optimizing dendritic cell immunity. However, the functions of Cnx in invertebrate innate immunity remain unclear. In this research, we characterized Cnx in the kuruma shrimp Marsupenaeus japonicus (designated as MjCnx) and detected its function in shrimp immunity. Sequence analysis showed that the full-length cDNA sequence of MjCnx was comprised2392bp with a113bp5’ untranslated region (UTR), a578bp3’ UTR containing a typical polyadenylation signal (AATAAA), and an open reading frame of1701bp. MjCnx encoded566amino acids, including a signal peptide of26residues, a Crt domain, and a TM region. MjCnx existed in several tissues of the shrimp, and the expression of MjCnx was upregulated in several tissues challenged with Vibrio anguillarum. Recombinant MjCnx can bind bacteria by binding polysaccharides. The recombinant protein enhanced the clearance of V. anguillarum in vivo, and the clearance effects were impaired after silencing MjCnx with RNA interference assay. Recombinant MjCnx. promoted phagocytosis efficiency. MjCnx not only existed in ER membrane but also existed on the hemocytes surface. MjCnx could sense the invading microorganisms by sense the pathogen associated molecular patterns and promote phagocytosis. These results suggest that MjCnx has crucial functions in shrimp antibacterial immunity.