Liu Yongjie, Song Lei, Sun Yuhang, Liu Tao, Hou Fujun, Liu Xiaolin
College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China.
Department of Politics Teaching Office, Military Economics Academy of Airforce, Wuhan 430035, China.
Dev Comp Immunol. 2016 Jul;60:41-52. doi: 10.1016/j.dci.2016.02.004. Epub 2016 Feb 6.
The Toll and immune deficiency (IMD) pathways are essential for inducing immune related genes during invasion of pathogens. In the present study, transcripts of eight pathway-related genes in Litopenaeus vannamei, including Toll, IMD, Pelle, IAP1, TRAF6, ALF, Crustin and Penaeidin3 were analyzed to further understand the potential relationship between Toll and IMD pathway. The high transcription levels of TRAF6, Pelle, Toll, IMD and IAP1 in selected tissues indicates their functional roles in Toll and IMD pathways. The increased mRNA expression of Toll and IMD detected in the early stage might suggest the inducible role of Toll and IMD upon bacterial infection. Moreover, the continuous increase of IMD and the high level of Pelle and TRAF6 in Vibrio anguillarum challenged group indicated that Gram-negative bacterium can activate both the Toll and IMD signaling pathway. Silencing of Toll by a dsRNA-mediated RNAi strongly increased the transcripts of IMD, Pelle, TRAF6, IAP1 and Akirin, knocking down of IMD also markedly increased the transcripts of Toll, Pelle, IAP1 and Akirin. Furthermore, ALF expression was significantly increased in response to V. anguillarum and Micrococcus lysodeikticus challenge, while the transcripts of Crustin and Pen3 in hemocytes were significantly reduced in V. anguillarum group, but rose significantly following M. lysodeikticus infection. In summary, we speculate that Toll and IMD pathway are not independent in shrimp, but linked to defense against bacterial infection.
Toll和免疫缺陷（IMD）信号通路在病原体入侵过程中对于诱导免疫相关基因至关重要。在本研究中，分析了凡纳滨对虾中8个与该信号通路相关基因的转录本，包括Toll、IMD、Pelle、IAP1、TRAF6、ALF、Crustin和Penaeidin3，以进一步了解Toll和IMD信号通路之间的潜在关系。所选组织中TRAF6、Pelle、Toll、IMD和IAP1的高转录水平表明它们在Toll和IMD信号通路中发挥功能作用。在早期检测到的Toll和IMD的mRNA表达增加可能表明Toll和IMD在细菌感染时具有诱导作用。此外，在鳗弧菌攻击组中，IMD的持续增加以及Pelle和TRAF6的高水平表明革兰氏阴性菌可激活Toll和IMD信号通路。通过dsRNA介导的RNAi沉默Toll可强烈增加IMD、Pelle、TRAF6、IAP1和Akirin的转录本，敲低IMD也显著增加Toll、Pelle、IAP1和Akirin的转录本。此外，ALF的表达在鳗弧菌和溶壁微球菌攻击后显著增加，而血细胞中Crustin和Pen3的转录本在鳗弧菌组中显著降低，但在溶壁微球菌感染后显著升高。总之，我们推测在对虾中Toll和IMD信号通路并非独立，而是与抵御细菌感染相关。
