Cg‐Rel, the first Rel/NF‐κB homolog characterized in a mollusk, the Pacific oyster Crassostrea gigas

• Published in: FEBS Letters
• Main Authors: Montagnani, C., Kappler, C., Reichhart, J.M., Escoubas, J.M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2004
• Subjects: Crassostrea gigas; Pacific oyster
• Online Access: http://dx.doi.org/10.1016/s0014-5793(04)00124-3; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1016%2FS0014-5793%2804%2900124-3; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1016%2FS0014-5793(04)00124-3; https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/S0014-5793%2804%2900124-3

We report here the identification and functional characterization of Cg ‐Rel, a gene encoding the Crassostrea gigas homolog of Rel/NF‐κB transcription factors found in insects and mammals. Sequence and phylogenetic analysis showed that Cg ‐Rel shares the structural organization of Rel/NF‐κB transcription factors of class II. It includes a Rel homology domain as well as a C‐terminal transactivation domain (TD). Overexpression of Cg ‐Rel in the Drosophila S2 cell line activated the expression of a NF‐κB‐dependent reporter gene, whereas transfection with a Cg ‐Rel construct containing a C‐terminal deletion of the TD or using a reporter gene with mutated κB binding sites failed to activate expression. These results suggest that Cg ‐Rel is a functional member of the Rel family of transcription factors, making this the sixth structurally homologous component of the Rel/NF‐κB pathway characterized in C. gigas . Based on homology to other invertebrates’ Rel/NF‐κB cascade, the function of the oyster pathway may serve to regulate genes involved in innate defense and/or development. These findings serve to highlight a potentially important regulatory pathway to the study of oyster immunology, hence allowing comparison of the immune system in vertebrates and invertebrates, an important key issue to understand its evolution.