Figure 2. EMS-induced mutagenesis on CHO cells reveals that a cellular receptor is required for the HBL’s cytolytic activity.
A. Schematic representation of EMS-induced mutagenesis to isolate HBL-resistant CHO mutant cells. CHO cells (50 million) seeded in ten 10-cm dishes were treated with 0.25 mM EMS for 24 h. Then, the cells were treated with HBL (2.5 nM each component) for 3 h. After toxin removal, the toxin-treated cells were cultured for one week, allowing formation and isolation of HBL-resistant CHO mutant clones.
B. Cytotoxicity of HBL to ten independent (from different dishes) HBL-resistant clones isolated in (A). The cells were incubated with various concentrations of HBL for 2 h, followed by an MTT assay to assess cell viability. Data are represented as mean ± SD.
C. HBL-resistant CHO mutant cells cannot bind HBL. Three representative HBL-resistant clones (CHO-R1, -R2, -R3) were incubated with HBL-B for 1 h, followed by sequential staining with a mouse anti-HBL-B serum and an anti-mouse IgG conjugated with Alexa Fluor 594.