Gene knockdown effects of upregulated genes on PrPres formation. (A) Immunoblotting of PrPres in N167 cells treated with siRNAs against four upregulated genes: Tmem179, Lrrc17, Mc1r, and Srd5a1. Cells in the presence of 5 μg/ml Gly-9 (Gly-9 +) or DMSO (Gly-9 −) were treated with a mixture of four siRNAs against the above-mentioned genes (si-RNA pool) at the indicated doses for 3 days after transfection. The amount of transfection reagent was equilibrated in all cell culture wells. (B) mRNA levels of Tmem179, Lrrc17, Mc1r, and Srd5a1 in N167 cells treated with specific siRNAs. Cells in the presence of 5 μg/ml Gly-9 were treated as described for panel A and were analyzed 24 h after transfection. Data are averages and standard deviations for triplicate experimental results (*, P < 0.01 versus control [transfection reagent alone]). (C) Pde4dip coding sequences and sites of siRNAs used in the study. (D) Immunoblotting of PrPres in N167 cells treated with siRNAs against Pde4dip. Cells in the presence of 5 μg/ml Gly-9 were treated with each siRNA (si-2, si-3, si-4, or si-5) at a dose of 10 nM for 3 days after transfection. The amount of transfection reagent was equilibrated in all cell culture wells. Graphic data are averages and standard deviations for triplicate immunoblot signals (*, P < 0.01 versus control [transfection reagent alone]). (E) Pde4dip mRNA levels in N167 cells treated with siRNAs against Pde4dip. Cells in the presence of vehicle (DMSO) or 5 μg/ml Gly-9 were treated as described for panel D and were analyzed at the indicated time points after transfection. Data are averages and standard deviations for triplicate experimental results (*, P < 0.01; **, P < 0.05 versus control [transfection reagent alone] at each time point). (F) PrP mRNA levels in N167 cells treated with siRNAs against Pde4dip. Cells were treated and analyzed as described for panel E. Data are averages and standard deviations for triplicate experimental results (*, P < 0.01; **, P < 0.05 versus control [transfection reagent alone] at each time point).