Comparison of IFN-γ and IFN-γ in antiviral, immune regulatory and apoptotic roles in fish (P6311)

Abstract

Abstract The cDNA and genomic sequences of grass carp IFN-γ and IFN-γ related (IFN-γrel) genes were cloned, with the absence of an NLS motif in IFN-γrel. IFN-γ and IFN-γrel differed in many aspects. Quantitative analysis revealed that IFN-γ was mainly expressed in spleen and intestine, while IFN-γrel was mainly expressed in gills and intestine, moderately in thymus and muscle. In peripheral blood leucocytes, the expression of IFN-γ and IFN-γrel were both up-regulated after PolyI:C and LPS treatment. Luciferase activities showed that IFN-γ could enhance interferon promoter activity and NF-κB promoter activity. The function of antivirus and antitumor roles was compared between IFN-γ and IFN-γrel in CIK cells. IFN-γ could induce expression of Mx, PKR, IRF1, SOCS1, TNF-α, while IFN-γrel did not have such roles. Nevertheless, IFN-γ and IFN-γrel could not induce the expression of Casp-3, Casp-9 and cathD. Furthermore, IFN-γ but not IFN-γrel inhibited the replication of GCRV, grass carp reovirus in CIK cells and prompted the apoptosis in CIK cells. Surprisingly, whatever IFN-γ was mutated with the deletion of 14 aa in C terminal or using GGGG substitution of RRRR had the similar effect as the intact IFN-γ in inducing the gene expression and the apoptosis. These results thus indicate IFN-γ is a functional homologous gene similar to IFN-γ in other higher vertebrates, while the role of IFN-γrel may need further investigation.