Expression of FANCJ-A349P fails to rescue sensitivity of FA-J cells to the G-quadruplex binding compound telomestatin and exerts a dominant-negative effect on telomestatin resistance of wild-type cells. (A) TMS sensitivity of stably transfected human FA-J (EUFA30/hTert/SV40) fibroblasts with the indicated genotypes was evaluated by survival assay. (B) γ-H2AX immunofluorescence staining of the corresponding FA-J cell lines stably transfected with plasmids encoding GFP, GFP-FANCJ-WT, or GFP-FANCJ-A349P. FA-J cells were untreated or treated with 5μM TMS for 4 hours, washed with PBS, allowed to recover for 4 hours, and analyzed by immunofluorescence detection. (C) Quantitative analyses of γ-H2AX foci after 5μM TMS exposure of the corresponding transfected FA-J cell lines shown in panel B. Data represent the mean of at least 100 cells counted, with SD indicated by error bars. (D) TMS sensitivity of stably transfected human wild-type (VH10/hTert) fibroblasts with the indicated genotypes was evaluated by survival assay. (E) γ-H2AX immunofluorescence staining of wild-type cells transfected with plasmids encoding GFP, GFP-tagged FANCJ-WT, or GFP-tagged FANCJ-A349P. Wild-type cells were either untreated or exposed to 5μM TMS for 4 hours, washed with PBS, allowed to recover for 4 hours, and analyzed by immunofluorescence detection. (F) Quantitative analyses of γ-H2AX foci in the corresponding transfected wild-type cell lines as shown in panel E.