LAUSR

Interleukin-1beta (IL-1β) is a cytokine involved in the control of inflammatory responses. The functions of IL-1β have been extensively studied in many vertebrates. However, few studies focused on the functions of IL-1β in the spotted halibut (Verasper variegatus), an endangered aquatic fish that easily suffers from bacterial and viral infections. We first cloned and sequenced the IL-1β gene from V. variegatus (VvIL-1β). Its conservative interleukin-1 propeptide and interleukin-1/18 domains corresponding regions, characteristics of the IL-1 protein family and TA-rich motifs relating to inflammatory responses were similar to those of the IL-1β genes from other teleost and mammals. The phylogenetic analysis showed that VvIL-1β was homologous to the IL-1β gene of other vertebrates. Treatment with pathogen-associated molecular patterns (PAMPs) induced a significant and rapid up-regulation of VvIL-1β expression in the peripheral blood leukocytes (PBLs), revealing that VvIL-1β is actively involved in the host immune responses against bacterial and viral pathogens. The expression level of VvIL-1β was relatively high in the PBLs, gill, and intestine, indicating the immunological function of VvIL-1β. VvIL-1β also had interesting expression patterns at specific developmental stages, implying that the IL-1β of flatfishes may have some novel functions during embryonic development and metamorphosis. The 3D structure prediction also provided information about how VvIL-1β interacts with its receptor protein. These results suggested that VvIL-1β may have multiple functions in V. variegatus and provided us valuable information for understanding the novel functions of IL-1β.