Department of Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.
Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.
Infect Immun. 2022 Aug 18;90(8):e0020522. doi: 10.1128/iai.00205-22. Epub 2022 Aug 1.
The role of specific host cell surface receptors during Toxoplasma gondii invasion of host cells is poorly defined. Here, we interrogated the role of the well-known malarial invasion receptor, basigin, in T. gondii infection of astrocytes. We found that primary astrocytes express two members of the BASIGIN (BSG) immunoglobulin family, basigin and embigin, but did not express neuroplastin. Antibody blockade of either basigin or embigin caused a significant reduction of parasite infectivity in astrocytes. The specific role of basigin during T. gondii invasion was further examined using a mouse astrocytic cell line (C8-D30), which exclusively expresses basigin. CRISPR-mediated deletion of basigin in C8-D30 cells resulted in decreased T. gondii infectivity. T. gondii replication and invasion efficiency were not altered by basigin deficiency, but parasite attachment to astrocytes was markedly reduced. We also conducted a proteomic screen to identify T. gondii proteins that interact with basigin. -encoded cyclophilins, the protein 14-3-3, and protein disulfide isomerase (TgPDI) were among the putative basigin-ligands identified. Recombinant TgPDI produced in E. coli bound to basigin and pretreatment of tachyzoites with a PDI inhibitor decreased parasite attachment to host cells. Finally, mutagenesis of the active site cysteines of TgPDI abolished enzyme binding to basigin. Thus, basigin and its related immunoglobulin family members may represent host receptors that mediate attachment of T. gondii to diverse cell types.
弓形虫感染宿主细胞时，特定宿主细胞表面受体的作用尚未明确。本研究探究了疟原虫入侵受体——basigin 在弓形虫感染星形胶质细胞中的作用。结果发现，原代星形胶质细胞表达两个 BASIGIN（BSG）免疫球蛋白家族成员，即 basigin 和 embigin，但不表达 neuroplastin。basigin 或 embigin 的抗体阻断均可显著降低星形胶质细胞中的寄生虫感染力。使用专门表达 basigin 的小鼠星形胶质细胞系（C8-D30）进一步研究了 basigin 在弓形虫入侵中的特定作用。CRISPR 介导的 C8-D30 细胞 basigin 缺失导致弓形虫感染性降低。basigin 缺乏并不改变弓形虫的复制和入侵效率，但寄生虫与星形胶质细胞的附着明显减少。我们还进行了蛋白质组筛选，以鉴定与 basigin 相互作用的弓形虫蛋白。-编码的亲环蛋白、蛋白 14-3-3 和蛋白二硫键异构酶（TgPDI）是鉴定出的潜在 basigin 配体之一。在大肠杆菌中产生的重组 TgPDI 与 basigin 结合，用 PDI 抑制剂预处理速殖子可降低寄生虫对宿主细胞的附着。最后，突变 TgPDI 的活性位点半胱氨酸可使酶与 basigin 的结合完全丧失。因此，basigin 及其相关免疫球蛋白家族成员可能代表介导弓形虫附着于多种细胞类型的宿主受体。
