Zhang Hong-Wei, Huang Ying, Man Xin, Wang Yue, Hui Kai-Min, Yin Shao-Wu, Zhang Xiao-Wen
College of Life Science, Henan Normal University, Xinxiang, Henan 453007, China; Division of Plant Sciences, University of Missouri, Columbia, MO 65201, USA.
Jiangsu Key Laboratory for Biodiversity & Biotechnology and Jiangsu Key Laboratory for Aquatic Crustacean Diseases, College of Life Sciences, Nanjing Normal University, Nanjing 210046, China.
Fish Shellfish Immunol. 2017 Apr;63:189-195. doi: 10.1016/j.fsi.2017.02.015. Epub 2017 Feb 16.
Toll-like receptors (TLRs) play an important role in the activation of innate immune response but their functions in bivalves remain largely unknown. In this study, we identified a TLR from the freshwater pearl mussel Hyriopsis cumingii (HcToll3) and investigated its functions in immunity. The full-length cDNA of HcToll3 is 3852 bp and includes an open reading frame (ORF) of 3228 bp that encodes a polypeptide of 1075 amino acids. The predicted HcToll3 protein shares similar structural characteristics with other known Toll family proteins. Quantitative real-time PCR analysis revealed that HcToll3 mRNA is broadly expressed in all of the examined tissues; its transcript level was significantly up-regulated by challenge with gram-negative bacteria Vibrio parahaemolyticus or lipopolysaccharide, but not gram-positive Staphylococcus aureus or peptidoglycan. RNA interference by siRNA results showed that HcToll3 regulated expression of whey acidic protein (HcWAP) and lysozymes (HcLyso1 and HcLyso2) in vivo and knockdown of HcToll3 suppressed the elimination of V. parahaemolyticus. These findings suggest that HcToll3 might be involved in anti-Vibrio defense in H. cumingii.
Toll样受体（TLRs）在激活先天免疫反应中发挥重要作用，但其在双壳贝类中的功能仍 largely未知。在本研究中，我们从淡水珍珠蚌三角帆蚌中鉴定出一种TLR（HcToll3），并研究了其在免疫中的功能。HcToll3的全长cDNA为3852 bp，包含一个3228 bp的开放阅读框（ORF），编码一个1075个氨基酸的多肽。预测的HcToll3蛋白与其他已知的Toll家族蛋白具有相似的结构特征。定量实时PCR分析表明，HcToll3 mRNA在所有检测组织中广泛表达；用革兰氏阴性菌副溶血性弧菌或脂多糖刺激后，其转录水平显著上调，但革兰氏阳性菌金黄色葡萄球菌或肽聚糖刺激后则不然。siRNA干扰结果表明，HcToll3在体内调节乳清酸性蛋白（HcWAP）和溶菌酶（HcLyso1和HcLyso2）的表达，敲低HcToll3可抑制副溶血性弧菌的清除。这些发现表明，HcToll3可能参与三角帆蚌的抗弧菌防御。
