Key Laboratory of East China Sea Fishery Resources Exploitation, Ministry of Agriculture and Rural affairs, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China.
Key Laboratory of East China Sea Fishery Resources Exploitation, Ministry of Agriculture and Rural affairs, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China.
Int J Biol Macromol. 2021 Dec 15;193(Pt B):2173-2182. doi: 10.1016/j.ijbiomac.2021.11.048. Epub 2021 Nov 13.
Although class B scavenger receptors (SR-Bs) in mammals are multifunctional molecules, the functions of SR-Bs in invertebrates remain largely unknown. In this study, we characterized an SR-B homolog, namely SpSR-B2, from Scylla paramamosain. SpSR-B2 shared high similarity with mammalian SR-Bs, and exhibited specific binding activity to ac-LDL, indicating that it may be a new member of SR-B class in invertebrates. SpSR-B2 was upregulated after challenge with white spot syndrome virus (WSSV) or bacteria. Binding assays showed that SpSR-B2 specifically interacted with WSSV envelope protein VP24. Besides, SpSR-B2 could bind to all tested bacterial cells and agglutinate these bacteria. SpSR-B2 also exhibited a strong binding activity to LPS but weak binding activities to other tested polysaccharides. These findings indicated that SpSR-B2 was a potential recognition molecule for viral protein VP24 and bacterial LPS. Knockdown of SpSR-B2 resulted in dramatically decreased expressions of certain antimicrobial peptides (AMPs), and overexpression of SpSR-B2 led to the increased expression of the AMP of SpALF2, suggesting that SpSR-B2 could regulate the expression of AMPs. Taken together, this study revealed that SpSR-B2 functioned as a potential pattern recognition receptor participating in antiviral and antibacterial immunity, and provided new insights into the immune functions of invertebrate SR-Bs.
虽然哺乳动物的 B 型清道夫受体 (SR-Bs) 是多功能分子，但无脊椎动物中 SR-Bs 的功能在很大程度上仍不清楚。在这项研究中，我们从锯缘青蟹 (Scylla paramamosain) 中鉴定了一种 SR-B 同源物，即 SpSR-B2。SpSR-B2 与哺乳动物的 SR-Bs 具有高度相似性，并表现出对 ac-LDL 的特异性结合活性，表明它可能是无脊椎动物中 SR-B 类的一个新成员。SpSR-B2 在受到白斑综合征病毒 (WSSV) 或细菌挑战后上调。结合实验表明，SpSR-B2 特异性地与 WSSV 包膜蛋白 VP24 相互作用。此外，SpSR-B2 可以与所有测试的细菌细胞结合并凝集这些细菌。SpSR-B2 还对 LPS 表现出强烈的结合活性，但对其他测试的多糖的结合活性较弱。这些发现表明 SpSR-B2 是病毒蛋白 VP24 和细菌 LPS 的潜在识别分子。SpSR-B2 的敲低导致某些抗菌肽 (AMPs) 的表达显著下降，而 SpSR-B2 的过表达导致 SpALF2 的 AMP 表达增加，表明 SpSR-B2 可以调节 AMPs 的表达。总之，这项研究表明 SpSR-B2 作为一种潜在的模式识别受体参与抗病毒和抗菌免疫，并为无脊椎动物 SR-Bs 的免疫功能提供了新的见解。
