A novel chemerin receptor 1 (Chemerin(1)) takes part in the immune response of cobia (Rachycentron canadum).

Chemerin receptor 1 (Chemerin(1)) plays a critical role in innate and adaptive immune systems. In this study, a cobia (Rachycentron canadum) Chemerin(1) was identified, and its molecular characterization and expression patterns were analyzed. Multiple sequence alignment revealed that the RcChemerin(1) possessed a typical dynein regulatory complex (DRC) motif. There was also a potential N-glycosylation site in the extracellular regions of the N-terminus and intracellular loops (ICL) 1 region. Phylogenetic analysis demonstrated that the RcChemerin(1) was clustered together with homologous proteins from other fish species. RcChemerin(1) was constitutively expressed in a wide range of tissues (especially in immune-related tissues) with different expression levels, which suggests that the RcChemerin(1) plays different roles in un-stimulated tissues. RcChemerin(1) expression showed up-regulation in the head kidney after Vibrio harveyi challenge. Up-regulation in the head kidney and spleen was also observed after polyinosinic-polycytidylic acid (poly I: C) challenge, which suggests that RcChemerin(1) may play vital roles during bacterial and viral infection. The differential responses of immune organs to bacteria and poly I: C imply the differences in defense mechanisms against viruses and bacteria.