Yang Hui-Ting, Yang Ming-Chong, Sun Jie-Jie, Guo Fang, Lan Jiang-Feng, Wang Xian-Wei, Zhao Xiao-Fan, Wang Jin-Xing
Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China.
Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China.
Fish Shellfish Immunol. 2015 Nov;47(1):63-73. doi: 10.1016/j.fsi.2015.08.021. Epub 2015 Aug 24.
Intestinal innate immune response is an important defense mechanism of animals and humans against external pathogens. The mechanism of microbiota homeostasis in host intestines has been well studied in mammals and Drosophila. The reactive oxygen species (ROS) and antimicrobial peptides have been reported to play important roles in homeostasis. However, how to maintain the microbiota homeostasis in crustacean intestine needs to be elucidated. In this study, we identified a novel catalase (MjCAT) involved in ROS elimination in kuruma shrimp, Marsupenaeus japonicus. MjCAT mRNA was widely distributed in hemocytes, heart, hepatopancreas, gills, stomach, and intestine. After the shrimp were challenged with pathogenic bacteria via oral infection, the expression level of MjCAT was upregulated, and the enzyme activity was increased in the intestine. ROS level was also increased in the intestine at early time after oral infection and recovered rapidly. When MjCAT was knocked down by RNA interference (RNAi), high ROS level maintained longer time, and the number of bacteria number was declined in the shrimp intestinal lumen than those in the control group, but the survival rate of the MjCAT-RNAi shrimp was declined. Further study demonstrated that the intestinal villi protruded from epithelial lining of the intestinal wall were damaged by the high ROS level in MjCAT-knockdown shrimp. These results suggested that MjCAT participated in the intestinal host-microbe homeostasis by regulating ROS level.
肠道固有免疫反应是动物和人类抵御外部病原体的重要防御机制。在哺乳动物和果蝇中，宿主肠道内微生物群稳态的机制已得到充分研究。据报道，活性氧（ROS）和抗菌肽在稳态中发挥重要作用。然而，甲壳类动物肠道中如何维持微生物群稳态仍有待阐明。在本研究中，我们在日本对虾（Marsupenaeus japonicus）中鉴定出一种参与ROS清除的新型过氧化氢酶（MjCAT）。MjCAT mRNA广泛分布于血细胞、心脏、肝胰腺、鳃、胃和肠道中。通过口服感染用病原菌攻击对虾后，MjCAT的表达水平上调，肠道中的酶活性增加。口服感染后早期，肠道中的ROS水平也升高，并迅速恢复。当通过RNA干扰（RNAi）敲低MjCAT时，ROS高水平维持的时间更长，与对照组相比，对虾肠腔内的细菌数量减少，但MjCAT-RNAi对虾的存活率下降。进一步研究表明，在敲低MjCAT的对虾中，高ROS水平破坏了从肠壁上皮内衬突出的肠绒毛。这些结果表明，MjCAT通过调节ROS水平参与肠道宿主-微生物群稳态。
