The alpha inhibitor of NF-κB (IκBα) from the mandarin fish binds with p65 NF-κB

The NF-kappa B/I kappa B alpha pathway plays an important role in the regulation of immune and inflammatory responses. I kappa B alpha is an inhibitory molecule that sequesters transcription activator NF-kappa B dimer in the cytoplasm of unstimulated cells. Here, we isolated the full-length cDNAs of the mandarin fish (Siniperca chuatsi) alpha inhibitor of NF-kappa B (SCI kappa B alpha) and p65 NF-kappa B (Scp65). Multiple sequence alignments showed that the amino acid sequences of both ScI kappa B alpha and Scp65 contain conserved domains similar to those of mammalian counterparts. Protein pull-down and coimmunoprecipitation assays showed that ScI kappa B alpha directly bound with Scp65. Real-time quantitative PCR analysis showed that ScI kappa B alpha mRNA was constitutive in all mandarin fish tissues detected. After challenge with infectious spleen and kidney necrosis virus (ISKNV), the mRNA level Of SCI kappa B alpha was decreased nearly 6 fold in the spleen. This result suggests that the NF-kappa B/I kappa B alpha. pathway in mandarin fish may play a role in the immune response against ISKNV. (C) 2009 Elsevier Ltd. All Fights reserved.