Figure 4.

MPG-mediated delivery of siRNA induces a robust biological response. (A) MPG-mediated delivery of a siRNA targeting the luciferase gene. MPG/siRNA or MPGΔ^NLS/DNA complexes were formed in DMEM at a charge ratio of 10:1 and incubated for 30 min at 37°C, then overlaid onto Cos-7 or HeLa cells grown to 60% confluence and previously transfected with the pRL-SV40 plasmid encoding the reporter gene luciferase. After 30 min incubation at 37°C, 1 ml of fresh DMEM supplemented with 10% FCS was added to the cells. Luciferase activity was measured 48 h after transfection. Transfections were also performed with Oligofectamine™ as a standard. Control experiments were performed with either naked siRNA or using a mismatch siRNA (dark grey bars). (B) MPG-mediated delivery of siRNA targeting the GAPDH gene: western blot analysis. Different concentrations of siRNA (25, 50 and 100 nM) were transfected with either MPG or MPGΔ^NLS and the levels of GAPDH protein were analysed by western blotting 30 h post-transfection. Actin was used as a control to normalise protein loading. (C) MPG-mediated delivery of siRNA targeting GAPDH gene: northern blot analysis. The kinetics of siRNA (50 nM)- induced degradation of GAPDH mRNA following transfection with either MPG or MPGΔ^NLS were analysed by northern blotting. Actin was used as a control to normalise mRNA levels in each sample.