CgIκB3, the third novel inhibitor of NF-kappa B (IκB) protein, is involved in the immune defense of the Pacific oyster, Crassostrea gigas. Issue 2 (October 2015)

• Record Type: Journal Article
• Authors: Xu, Fengjiao; Li, Jun; Zhang, Yuehuan; Li, Xiaomei; Zhang, Yang; Xiang, Zhiming; Yu, Ziniu
• Is Part Of: Fish & shellfish immunology. Volume 46:Issue 2(2015:Oct.)
• Page Start: 648
• Page End: 655
• Publication Date: 2015-10
• Subjects: Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2015.08.002
• Languages: English
• ISSNs: 1050-4648

Abstract

<abstract xml:lang="en" abstract-type="author" id="abs0010"> <title id="sectitle0010">Abstract</title> <sec> <p id="abspara0010">Inhibitor of NF-κB (IκB), the important regulator of NF-κB/Rel signaling pathway, plays the crucial role in immune response of both vertebrates and invertebrates. Here, a novel homologue of IκB was cloned from <italic>Crassostrea gigas</italic>, and designated as <italic>Cg</italic>IκB3. The complete <italic>Cg</italic>IκB3 cDNA was 1282 bp in length, including a 942 bp open reading frame (ORF), a 51 bp 5′ UTR and a 289 bp 3′ UTR. The ORF encodes a putative protein of 313 amino acids with a predicted molecular weight of approximately 34.7 kDa. Sequence analysis reveals that <italic>Cg</italic>IκB3 contains a conserved degradation motif but with only five ankyrin repeats. Neither a PEST domain nor a C-terminal casein kinase II phosphorylation site was identified through either alignment or bioinformatic prediction. Phylogenetic analysis suggested that <italic>Cg</italic>IκB3 shares common ancestor with <italic>Cg</italic>IκB1 rather <italic>Cg</italic>IκB2, and theoretically it may originate from one duplication event prior to divergence of <italic>Cg</italic>IκB1 and <italic>Cg</italic>IκB2. Tissue expression analyses demonstrated that <italic>Cg</italic>IκB3 mRNA is the most abundant in gills and heart. The expression following PAMP infection showed that <italic>Cg</italic>IκB3 was significantly up-regulated in a similar pattern when challenged with LPS, HKLM or HKVA, respectively. Moreover, similar to <italic>Cg</italic>IκB1 and <italic>Cg</italic>IκB2, <italic>Cg</italic>IκB3 can also inhibit Rel dependent NF-κB activation in HEK293 cells in a dose-dependent manner. In summary, these findings suggest that <italic>Cg</italic>IκB3 can be as the functional inhibitor of NF-κB/Rel and involved in the host defense of <italic>C. gigas</italic>. The discovery of the third IκB emphasizes the complexity and importance of the regulation on NF-κB activation.</p> </sec> </abstract>