Molecular cloning and characterisation of a homologue of the alpha inhibitor of NF-κB in the griffon vulture (Gyps fulvus)

NF-κB has been found to play roles in many different compartments of the immune system during differentiation of immune cells and development of lymphoid organs and during immune activation. The activity of NF-κB is primarily regulated by a family of structurally related proteins known as the IκB proteins. Herein, we report the molecular cloning and characterisation of a griffon vulture (Gyps fulvus) orthologue of the alpha inhibitor of NF-κB (IκBα). The full-length cDNA consists of 1553 bp with an ORF encoding a 313 amino acids protein (GenBank accession number EU161944). The putative G. fulvus IκBα protein (Gf-IκBα) possesses the characteristic organization of the mammalian IκBα proteins. Gf-IκBα contains an N-terminal signalling receiver domain, a central ankyrin repeat domain, required for its interaction with NF-κB, and a putative PEST-like sequence in the C-terminus. Quantitative real-time RT-PCR (qRT-PCR) analysis indicated that Gf-IκBα mRNA levels were higher in vulture heart, lung, artery and PBMC cells than in small and large intenstine and kidney. The predicted amino acid sequence of Gf-IκBα was 73% identical to human IκBα, and 91% identical to chicken IκBα. These results confirm the existence of the NF-κB signalling pathway in vulture and suggest a similar functional interaction between IκBα and NF-κB. Based on the results and the homology to the vertebrate NF-κB cascade, these studies help to highlight a potentially important regulatory pathway for the study of the related functions in vulture immune system.