Fig. 4.

Effects of SC13 on DNA repair efficiency. a. Effects of SC13 on FEN1 activity. b. Okazaki fragment maturation assay. A gap substrate with a RNA-DNA flap was incubated with cell lysates and increasing amounts of SC13. Reconstitution of long-patch (LP) base excision repair (BER) with cell lysate (c) or purified proteins (d). A tetrahydrofuran (THF)-containing oligo was used to mimic the LP-BER substrate. e. Reconstitution of short-patch BER with purified proteins. An uracil-containing oligo was used to mimic the short-patch BER substrate. The top of each panel shows the schematic structures of the corresponding DNA substrates. The middle panel shows PAGE-separated products, and the bottom panel shows the relative percentage of cleavage of substrate. The values represent the mean ± SD of three independent assays. f. Procedure of LP-BER assay in cells. A DNA oligo containing the damaged DNA lesion 8-oxo-dG was transfected into MCF7 cells; 4 h later, cells were lysed, and released 8-oxo-dG was determined by ELISA. g. Effects of SC13 on LP-BER in cells. h. Cell-based homologous recombination (HR) repair assay. U2OS-DR-GFP cells were transfected with I-Sce I plasmid and treated with SC13 or DMSO (as a negative control).