RESUMO
NOD1 and NOD2 as two representative members of nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family play important roles in antimicrobial immunity. However, transcription mechanism of nod1 and nod2 and their signal circle are less understood in teleost fish. In this study, with the cloning of card9 and ripk2 in Chinese perch, the interaction between NOD1, NOD2, and CARD9 and RIPK2 were revealed through coimmunoprecipitation and immunofluorescence assays. The overexpression of NOD1, NOD2, RIPK2 and CARD9 induced significantly the promoter activity of NF-κB, IFNh and IFNc. Furthermore, it was found that nod1 and nod2 were induced by poly(I:C), type I IFNs, RLR and even NOD1/NOD2 themselves through the ISRE site of their proximal promoters. It is thus indicated that nod1 and nod2 can be classified also as ISGs due to the presence of ISRE in their proximal promoter, and their expression can be mechanistically controlled through PRR pathway as well as through IFN signaling in antiviral immune response.
Assuntos
Proteínas de Peixes , Proteína Adaptadora de Sinalização NOD1 , Proteína Adaptadora de Sinalização NOD2 , Proteína Serina-Treonina Quinase 2 de Interação com Receptor , Transdução de Sinais , Animais , Proteína Adaptadora de Sinalização NOD1/genética , Proteína Adaptadora de Sinalização NOD1/metabolismo , Proteína Serina-Treonina Quinase 2 de Interação com Receptor/metabolismo , Proteína Serina-Treonina Quinase 2 de Interação com Receptor/genética , Proteína Adaptadora de Sinalização NOD2/genética , Proteína Adaptadora de Sinalização NOD2/metabolismo , Proteínas de Peixes/genética , Proteínas de Peixes/metabolismo , Proteínas de Peixes/imunologia , Percas/genética , Percas/imunologia , Percas/metabolismo , Interferons/metabolismo , Interferons/genética , Regiões Promotoras Genéticas , Transcrição Gênica , Imunidade Inata/genética , Ligação ProteicaRESUMO
The type IV IFN (IFN-υ) is reported in vertebrates from fish to primary mammals with IFN-υR1 and IL-10R2 as receptor subunits. In this study, the proximal promoter of IFN-υ was identified in the amphibian model, Xenopus laevis, with functional IFN-sensitive responsive element and NF-κB sites, which can be transcriptionally activated by transcription factors, such as IFN regulatory factor (IRF)1, IRF3, IRF7, and p65. It was further found that IFN-υ signals through the classical IFN-stimulated gene (ISG) factor 3 (ISGF3) to induce the expression of ISGs. It seems likely that the promoter elements of the IFN-υ gene in amphibians is similar to type III IFN genes, and that the mechanism involved in IFN-υ induction is very much similar to type I and III IFNs. Using recombinant IFN-υ protein and the X. laevis A6 cell line, >400 ISGs were identified in the transcriptome, including ISGs homologous to humans. However, as many as 268 genes were unrelated to human or zebrafish ISGs, and some of these ISGs were expanded families such as the amphibian novel TRIM protein (AMNTR) family. AMNTR50, a member in the family, was found to be induced by type I, III, and IV IFNs through IFN-sensitive responsive element sites of the proximal promoter, and this molecule has a negative role in regulating the expression of type I, III, and IV IFNs. It is considered that the current study contributes to the understanding of transcription, signaling, and functional aspects of type IV IFN at least in amphibians.
