Fig. 2

Intracellular instead of intercellular IFNβ induces suppressive effects against LINE-1 retrotransposition in HEK293T cells. A qRT-PCR data showing that exogenous MDA5 expression elevates IFNβ expression in HEK293T cells. HEK293T cells were transfected with 45 ng of MDA5-expressing vector and subjected to qRT-PCR at 48 h post-transfection. B Flow cytometry data indicating that the addition of IFNβ in culture medium does not induce LINE-1 suppression in HEK293T cells. HEK293T cells pre-treated with commercial IFNβ protein (2.5, 25, or 250 U/ml, final concentration) were transfected with 1 μg of L1-RPS. At 96 h post-transfection, the cells were collected to detect EGFP-positive cells through flow cytometry. C Flow cytometry data showing that IFNβ effectively induces HIV suppression in THP-1 cells. THP-1 cells pre-treated with commercial IFNβ protein (2.5, 25, or 250 U/ml, final concentration) were infected with VSVg-coated NL4–3 Δenv EGFP pseudovirus, and subjected to flow cytometry at 48 h post-infection to detect EGFP-positive cells. D qRT-PCR results showing that the expression of ISGs can be triggered by intracellular IFNβ. HEK293T cells were transfected with 135 ng of control vector VR1012 or 15, 45, or 135 ng of IFNβ-expressing vector, and subjected to qRT-PCR to detect endogenous levels of MX2, OAS2, and OAS3 mRNA. Endogenous ACTB mRNA levels were used to equilibrate the results, but are not shown. E Flow cytometry data suggesting that intracellular IFNβ induces suppressive effects against LINE-1 retrotransposition in HEK293T cells. HEK293T cells seeded on a 24-well plate were co-transfected with 1 μg of L1-RPS and 225 ng of control vector VR1012 or 25, 75, or 225 ng of IFNβ-expressing vector. Cells were collected at 96 h post-transfection to detect EGFP-positive cells through flow cytometry. Western blotting results above indicate the IFNβ and MDA5 protein levels in transfected cells