Role of sericin 1 in the immune system of silkworms revealed by transcriptomic and proteomic analyses after gene knockout

The domestic silkworm is a type of lepidopteran insect that feeds on mulberry leaves and has high economic value because of its ability to spin cocoons. Sericin 1 is an important component of silkworm cocoons, accounting for approximately 25% of the material. In this study, CRISPR/Cas9-mediated gene editing was successfully used to destroy the sericin 1 gene, and homozygous mutants were obtained after continuous screening. Homozygous mutation resulted in premature termination of the translation of sericin 1 protein at 323 amino acids. Comparative transcriptomic and proteomic analyses of middle silk gland cells from wild-type individuals and mutants were performed on the fourth day of the fifth instar, and the results suggest that sericin 1 plays an important role in the cellular immune system. In addition, the results suggest that sericin 1 has a synergistic effect with some protease inhibitors and that the secretion of these proteins is strictly regulated. These results will provide new insights into the function and expression pattern of sericin 1 and the mechanism of silk secretion.

家蚕是一类以桑叶为食的鳞翅目昆虫，因其具备结茧能力而拥有极高的经济价值。丝胶蛋白1（Sericin 1）是蚕茧的重要组成成分，约占蚕茧总物质的25%。本研究成功利用CRISPR/Cas9介导的基因编辑技术敲除丝胶蛋白1基因，并经连续筛选获得纯合突变体。纯合突变导致丝胶蛋白1的翻译在第323位氨基酸处提前终止。本研究于五龄第四天采集野生型个体与突变体的中部丝腺细胞，开展比较转录组与蛋白质组学分析，结果显示丝胶蛋白1在细胞免疫系统中发挥重要作用。此外，研究结果还表明丝胶蛋白1与部分蛋白酶抑制剂存在协同作用，且这类蛋白质的分泌过程受到严格调控。本研究结果可为解析丝胶蛋白1的功能、表达模式以及蚕丝分泌机制提供新的研究视角。