College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China.
Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA.
Toxins (Basel). 2024 Aug 21;16(8):369. doi: 10.3390/toxins16080369.
harboring Binary (BinA and BinB) toxins is highly toxic against and mosquito larvae. The Ag55 cell line is a suitable model for investigating the mode of Bin toxin action. Based on the low-levels of α-glycosidase Agm3 mRNA in Ag55 cells and the absence of detectable Agm3 proteins, we hypothesized that a scavenger receptor could be mediating Bin cytotoxicity. Preliminary RNA interference knockdown of the expressed scavenger receptors, combined with Bin cytotoxicity assays, was conducted. The scavenger Receptor C1 (SCRC1) became the focus of this study, as a putative receptor for Bin toxins in Ag55 cells, and SCRBQ2 was selected as a negative control. Open reading frames encoding SCRC1 and SCRBQ2 were cloned and expressed in vitro, and polyclonal antibodies were prepared for immunological analyses. The RNAi silencing of SCRC1 and SCRBQ2 resulted in the successful knockdown of both SCRC1 and SCRBQ2 transcripts and protein levels. The cytolytic toxicity of Bin against Ag55 cells was severely reduced after the SCRC1-RNAi treatment. The phagocytic receptor protein SCRC1 mediates endocytosis of the Bin toxin into Ag55 cells, thereby facilitating its internal cytological activity. The results support a mechanism of the Bin toxin entering Ag55 cells, possibly via SCRC1-mediated endocytosis, and encourage investigations into how Bin is transferred from its bound form on the midgut epithelial cells into the epithelial endocytic system.
（BinA 和 BinB）二元毒素对 和 蚊幼虫具有高度毒性。Ag55 细胞系是研究 Bin 毒素作用模式的合适模型。基于 Ag55 细胞中 α-糖苷酶 Agm3 mRNA 水平低和无法检测到 Agm3 蛋白，我们假设可以通过清道夫受体介导 Bin 细胞毒性。初步的 RNA 干扰敲低表达的清道夫受体，并结合 Bin 细胞毒性测定进行了实验。清道夫受体 C1（SCRC1）成为本研究的焦点，因为它可能是 Ag55 细胞中 Bin 毒素的受体，而 SCRBQ2 被选为阴性对照。编码 SCRC1 和 SCRBQ2 的开放阅读框在体外进行了克隆和表达，并制备了多克隆抗体进行免疫分析。SCRC1 和 SCRBQ2 的 RNAi 沉默导致 SCRC1 和 SCRBQ2 的转录本和蛋白水平的成功敲低。SCRC1-RNAi 处理后，Bin 对 Ag55 细胞的细胞毒性明显降低。吞噬受体蛋白 SCRC1 介导 Bin 毒素进入 Ag55 细胞的内吞作用，从而促进其细胞内细胞学活性。结果支持 Bin 毒素进入 Ag55 细胞的机制，可能通过 SCRC1 介导的内吞作用，并鼓励进一步研究 Bin 如何从其结合形式在中肠上皮细胞转移到上皮内吞系统。
