Fig. 6.

LGP2 inhibits IR-induced cytotoxic IFNβ. (A) LGP2 suppresses IR-induced activation of IFNβ promoter. HEK293 cells were stably transduced with shRNA directed to LGP2 or shNT. Cells were transfected with pGL3–Ifnβ and pRL–SV40, irradiated (indicated dose), and collected 72 h after IR. Firefly luciferase activity was normalized to Renilla luciferase activity and is expressed relative to nonirradiated cells. (B) Neutralizing antibodies to IFNβ prevent cytotoxic effects of LGP2 depletion. D54 cells were depleted of LGP2 with siRNA (Fig. 2C) and irradiated at 0, 3, or 6 Gy in the presence or absence of neutralizing antibody to IFNβ (1 μg/mL). Cell viability was assessed 96 h post-IR using methylene blue assay. Data are normalized to nontargeting siRNA at 0 Gy and represented as means with error bars showing SDs for assays performed at least in triplicate. Significance was measured using two-tailed t test (*P < 0.05).