Characterization, expression, and functional study of IRAK-1 from grouper, Epinephelus coioides. (September 2016)

• Record Type: Journal Article
• Authors: Li, Yan-Wei; Zhao, Fei; Mo, Ze-Quan; Luo, Xiao-Chun; Li, An-Xing; Dan, Xue-Ming
• Is Part Of: Fish & shellfish immunology. Volume 56(2016:Sep.)
• Page Start: 374
• Page End: 381
• Publication Date: 2016-09
• Subjects: Epinephelus coioides -- IRAK-1 -- Signal transduction -- Cryptocaryon irritans; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2016.06.030
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: As crucial components of the toll-like receptor (TLR) and interleukin-1 (IL-1) receptor (IL-1R) signaling pathways, interleukin-1 receptor associated kinase (IRAK) family members play essential roles in an animal's immune response. In this study, an IRAK family member, designated EcIRAK-1, was identified in the orange-spotted grouper Epinephelus coioides, and its role in signal transduction investigated. The full-length EcIRAK-1 gene is 2822 bp, encoding a 760-amino-acid protein that has the typical characteristics of mammalian IRAK-1, including an N-terminal death domain, a ProST domain, a central kinase domain, and C-terminal C1 and C2 domains. EcIRAK-1 shares 42%–79% sequence identity with other fish IRAK-1 proteins, and the death and kinase domains are more conserved than the other domains. Several important amino acids and motifs of mammalian IRAK-1 are also conserved in the grouper and other piscine IRAK-1s. In healthy grouper, EcIRAK-1 was broadly expressed in all the tissues tested, with the highest expression in the gill and skin. After infection with Cryptocaryon irritans, EcIRAK-1 expression increased in the gill and spleen. After its exogenous expression in HEK293T cells, EcIRAK-1 significantly activated nuclear factor kappaB (NF-κB). The death domain, ProST domain, and some conserved amino acids, such as T58, T207, K237, and T387, in EcIRAK-1 are required for its signaling function. These data demonstrate that piscine IRAK-1 has the same structural characteristics as its mammalian counterpart and that its function is conserved among vertebrates. Highlights: An IRAK-1 sequence was identified in the grouper, Epinephelus coioides. EcIRAK-1 shares conserved structural characteristics with that of other species. EcIRAK-1 expression increases in the gill and spleen after Cryptocaryon irritans infection. EcIRAK-1 activation of NF-κB depends on its death and kinase domains. Mutation of some conserved amino acids reduced EcIRAK-1 function.