Figure 6. Quantification of telomere G-tail length by hybridization protection assay in DNA-PKcs knockdown U-2 OS cells. (A) A schematic of the HPA for telomere G-tail. Non-denatured genomic DNA was incubated with acridinium ester (AE)-labeled 29-mer telomere HPA probe. The AE of unhybridized and mis-hybridized probes was hydrolyzed, and chemilumines-cence from AE of hybridized probes was measured. (B and C) G-tail length of cells expressing an shRNA control or an shRNA against WRN was examined in panel B. G-tail length of cells transfected with siRNA against control (left), siRNA against DNA-PKcs (middle left), siRNA against DNA-PKcs with pEYFP-WRN (middle right), or siRNA against DNA-PKcs with pEYFP-WRN (E84A) (right) was examined in panel C. The G-tail length in the control cells was represented as 100%. Data are represented as mean +/- standard errors of two independent experiments.