DataSheet_1_The ECSIT Mediated Toll3-Dorsal-ALFs Pathway Inhibits Bacterial Amplification in Kuruma Shrimp.docx

The Toll signaling pathway plays an important role in animal innate immunity. However, its activation and signal transmission greatly differ across species and need to be investigated. Shrimp farming is a worldwide economic activity affected by bacterial disease from the 1990s, which promoted research on shrimp immunity. In this study, we first proved that, among the three identified Toll receptors in Marsupenaeus japonicus kuruma shrimp, Toll 3 plays a pivotal role in initiating the antibacterial response in vivo, especially upon anti-Staphylococcus aureus infection. Further research showed that this result was due to the activation of the Dorsal transcription factor, which induced the expression of two anti-lipopolysaccharide factors (Alfs). Moreover, the evolutionarily conserved signaling intermediate in Toll pathways, ECSIT, was proved to be needed for signal transmission from Toll 3 to Dorsal and the expression of anti-lipopolysaccharide factors. Finally, the mortality assay showed that a Toll3-ECSIT-Dorsal-Alf axis was functional in the anti-S.aureus immunity of M. japonicus shrimp. The results provide new insights into the function and signal transduction of the Toll pathway in aquatic species and offer basic knowledge for shrimp disease control and genetic breeding.

Toll信号通路（Toll signaling pathway）在动物先天免疫中发挥着重要作用。然而，不同物种间其激活机制与信号传导过程存在显著差异，有待进一步研究阐明。自20世纪90年代起，细菌性病害对全球对虾养殖这一重要经济产业造成严重冲击，这一现状推动了对虾免疫相关研究的开展。本研究首先证实，在日本囊对虾（Marsupenaeus japonicus）已鉴定的3种Toll受体中，Toll 3在体内抗菌免疫应答的启动过程中发挥关键作用，尤其是在抗金黄色葡萄球菌（Staphylococcus aureus）感染时。后续研究表明，这一效应源于Dorsal转录因子的激活——该因子可诱导两种抗脂多糖因子（anti-lipopolysaccharide factors, ALFs）的表达。此外，研究证实Toll通路中进化保守的信号中介蛋白ECSIT是介导Toll 3向Dorsal传递信号、以及诱导抗脂多糖因子表达所必需的分子。最终的死亡率实验表明，Toll3-ECSIT-Dorsal-ALF信号轴在日本囊对虾抗金黄色葡萄球菌免疫中发挥了功能性作用。本研究结果为解析水生生物Toll通路的功能与信号转导机制提供了新视角，同时为对虾病害防控与遗传育种研究提供了理论基础。