Rao Xiang-Jun, Wu Peng, Shahzad Toufeeq, Liu Su, Chen Ling, Yang Yun-Fan, Shi Qiao, Yu Xiao-Qiang
School of Plant Protection, Anhui Agricultural University, Hefei, Anhui 230036, PR China.
School of Plant Protection, Anhui Agricultural University, Hefei, Anhui 230036, PR China.
Dev Comp Immunol. 2016 Jul;60:149-59. doi: 10.1016/j.dci.2016.03.001. Epub 2016 Mar 2.
Galectins (S-type lectins) are an ancient family of lectins with the β-galactoside binding activity. In mammals, galectins play essential roles in many biological processes, such as development, immune homeostasis and tumor progression. However, few studies have been devoted to their functions in insects. Here, we characterized the only dual-CRD galectin in the silkworm Bombyx mori (BmGalectin-4). BmGalectin-4 cDNA possesses an open reading frame of 1089 bp, which encodes a putative galectin of 363 amino acids containing tandem carbohydrate recognition domains (CRDs). BmGalectin-4 was expressed in various tissues but the protein was most abundant in fertilized eggs. Its transcript level in fertilized eggs was upregulated upon bacterial challenge. Recombinant BmGalectin-4 purified from Escherichia coli bound to bacterial cell wall components and bacterial cells. In addition, the recombinant protein induced bacterial agglutination, but did not have antibacterial activity against selected microorganisms. Taken together, our results suggest that BmGalectin-4 may function as a pattern recognition receptor primarily in silkworm fertilized eggs.
半乳糖凝集素（S型凝集素）是一类古老的具有β-半乳糖苷结合活性的凝集素家族。在哺乳动物中，半乳糖凝集素在许多生物学过程中发挥着重要作用，如发育、免疫稳态和肿瘤进展。然而，关于它们在昆虫中的功能研究较少。在此，我们对家蚕中唯一的双CRD半乳糖凝集素（BmGalectin-4）进行了表征。BmGalectin-4 cDNA拥有一个1089 bp的开放阅读框，编码一个推定的含有串联碳水化合物识别结构域（CRD）的363个氨基酸的半乳糖凝集素。BmGalectin-4在各种组织中均有表达，但在受精卵中蛋白质含量最为丰富。在细菌攻击后，其在受精卵中的转录水平上调。从大肠杆菌中纯化的重组BmGalectin-4与细菌细胞壁成分和细菌细胞结合。此外，重组蛋白诱导细菌凝集，但对所选微生物没有抗菌活性。综上所述，我们的结果表明BmGalectin-4可能主要在家蚕受精卵中作为一种模式识别受体发挥作用。
