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Tumor necrosis factor receptor-associated factor 6 (TRAF6) participates in anti-lipopolysaccharide factors (ALFs) gene expression in mud crab

Sun, Wan-wei, Zhang, Xin-xu, Wan, Wei-song, Wang, Shu-qi, Wen, Xiao-bo, Zheng, Huai-ping, Zhang, Yue-ling, Li, Sheng-kang
Developmental and comparative immunology 2017 v.67 pp. 361-376
Portunus trituberculatus, RNA interference, Scylla paramamosain, Vibrio parahaemolyticus, amino acids, crabs, cytoplasm, gene expression, genes, heart, hemocytes, hepatopancreas, interleukin-1, open reading frames, pathogens, quantitative polymerase chain reaction, reverse transcriptase polymerase chain reaction, small interfering RNA, stomach, tumor necrosis factors, zinc finger motif
Tumor necrosis factor receptor-associated factor 6 (TRAF6) is a key cytoplasm signal adaptor that mediates signals activated by tumor necrosis factor receptor (TNFR) superfamily and the Interleukin-1 receptor/Toll-like receptor (IL-1/TLR) superfamily. The full-length 2492 bp TRAF6 (Sp-TRAF6) from Scylla paramamosain contains 1800 bp of open reading frame (ORF) encoding 598 amino acids, including an N-terminal RING-type zinc finger, two TRAF-type zinc fingers and a conserved C-terminal meprin and TRAF homology (MATH) domain. Multiple alignment analysis shows that the putative amino acid sequence of Sp-TRAf6 has highest identity of 88% with Pt-TRAF6 from Portunus trituberculatus, while the similarity of Sp-TRAF6 with other crustacean sequences was 54–55%. RT-PCR analysis indicated that Sp-TRAF6 transcripts were predominantly expressed in the hepatopancreas and stomach, whereas it was barely detected in the heart and hemocytes in our study. Moreover, Sp-TRAF6 transcripts were significantly up-regulated after Vibrio parahemolyticus and LPS challenges. RNA interference assay was carried out used by siRNA to investigate the genes expression patterns regulated by Sp-TRAF6. The qRT-PCR results showed that silencing Sp-TRAF6 gene could inhibit SpALF1, SpALF2, SpALF5 and SpALF6 expression in hemocytes, while inhibit SpALF1, SpALF3, SpALF4, SpALF5 and SpALF6 expression in hepatopancreas. Taken together, the acute-phase response to immune challenges and the inhibition of SpALFs gene expression indicate that Sp-TRAF6 plays an important role in host defense against pathogen invasions via regulation of ALF gene expression in S. paramamosain.