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A Converging Strategy for the Generation of a Virtually Sequenced cDNA Library from Unreferenced Pacific Oysters
Published on: June 13, 2019
Molecular characterization of Pacific oyster (Crassostrea gigas) IRAK4 gene and its role in MyD88-dependent pathway
Xueying Tang1, Baoyu Huang2, Linlin Zhang2
1Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China; University of Chinese Academy of Sciences, Beijing 100039, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266071, China; National & Local Joint Engineering Laboratory of Ecological Mariculture, Qingdao, Shandong 266071, China.
Abstract:
Interleukin-1 receptor-associated kinases (IRAKs) play important roles in MyD88-dependent TLR signaling, the crucial innate immune pathway in molluscs. In this study, we examined the full-length IRAK4 genetic sequence in the Pacific oyster (Crassostrea gigas) by molecular cloning. Phylogenetic analysis revealed that CgIRAK4 is most closely related to Mytilus edulis, and forms a clade with other molluscs. CgIRAK4 transcripts are widely expressed in all tissues, with the highest expression observed in the hemocytes and gill. Moreover, CgIRAK4 is significantly upregulated after Oyster herpesvirus-1 microvariant (OsHV-1 μvar), Vibrio alginolyticus, and poly I:C challenge. Yeast two-hybrid and co-immunoprecipitation assays reveal that the CgIRAK4 death domain is necessary to mediate interaction between CgIRAK4 and two CgMyD88 isoforms. In addition, CgIRAK4 overexpression cannot induce NF-κB transcriptional activity, but blocks that induced by CgMyD88 in HEK293T cells. These findings elucidate the mechanisms of MyD88-dependent TLR signaling in molluscs, and the differences in IRAK-mediated pathway activation between invertebrates and vertebrates.
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