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Fish Shellfish Immunol. 2014 Oct;40(2):455-65. doi: 10.1016/j.fsi.2014.07.026. Epub 2014 Aug 1.

Genomic characterization and expression analysis of five novel IL-17 genes in the Pacific oyster, Crassostrea gigas.

Author information

1
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
2
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China. Electronic address: carlzyu@scsio.ac.cn.

Abstract

Interleukin-17 (IL-17) is a proinflammatory cytokine that plays an important role in clearing extracellular bacteria and contributes to the pathology of many autoimmune and allergic conditions. In the present study, five novel IL-17 homologs were identified by searching and analyzing the Pacific oyster genome. All six CgIL-17 members (including a previously reported homolog) contained four conserved cysteines that were used in the formation of disulfide bonds. Phylogenetic analysis showed that all invertebrate IL-17s were clustered into one group, implying that invertebrate IL-17s evolved from one common ancestral gene and subsequently diversified. All CgIL-17s shared the same genomic structure, containing two exons and one intron, except for the CgIL-17-3 and CgIL-17-5 genes, which each had only one exon. The expression pattern of the CgIL-17 genes was analyzed by qRT-PCR in a variety of tissues and at different developmental stages, and these genes were highly expressed in the gill and digestive gland tissues. Moreover, the expression of the CgIL-17 family genes was significantly up-regulated in hemocytes challenged with Pathogen-Associated Molecular Patterns (PAMPs). CgIL-17-3 had a strong response to lipopolysaccharide (LPS) and heat-killed Vibrio alginolyticus (HKVA) challenge, while CgIL-17-5 and CgIL-17-6 can be activated by peptidoglycan (PGN), but not by heat-killed Listeria monocytogenes (HKLM). The distinct, up-regulated transcript levels of the CgIL-17s in response to PAMPs challenge further indicate that CgIL-17s are likely to be significant components of immune responses by playing diversified roles in host defense in the Pacific oyster. These findings suggest that CgIL-17s are involved in innate immune responses and further supports their conserved function in mollusks immunity.

KEYWORDS:

Genomic organization; Interleukin-17; PAMPs challenge; Pacific oyster

PMID:
25090939
DOI:
10.1016/j.fsi.2014.07.026
[Indexed for MEDLINE]

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