Figure 1.

Genome-wide genetic screen of provirus silencing factor. (A) Scheme of gRNA vecter (top) and the provirus MSCV-GFP reporter mouse ES cell lines (bottom) for the screen. (B) Validation of provirus silencing by SETDB1 in the reporter cell line. Setdb1 gRNA plasmid only (green) or both Setdb1 gRNA plasmid and transgene (blue) were transfected into clone 7, followed by flow cytometric analysis of GFP expression at 5 d after transfection. (C) Scheme of genome-wide genetic screen of provirus silencing factor by lentiviral gRNA library. (D) Analysis of the screening result by MAGeCK. X- and y-axes indicate rank of genes and –log₁₀(P-value), respectively. P-values of top 222 genes were less than 0.01. All top-ranked genes listed in the red box have been known as a repressor of retroelement. (E) Validation of the top 46 genes by gRNA inactivation. Each gRNA plasmid of the top 46 genes was transfected into clone 7, and GFP expressions were analyzed by flow cytometry at 5 d after transfection. (F) GO term enrichment analysis for biological process of top 100 genes performed by DAVID. (G) Comparison of the top 100 genes between our screen and siRNA screen in Yang et al. (2015). See also Supplemental Figure S1.