Fig. 2

Comparison of different dCas9/gRNA systems for labeling human telomeres. a The dCas9-labeling (SunTag) and gRNA-labeling (20XPBSc, 24XMBSV5, and 2XMS2) systems were tested in HEK293T cells. A gRNA-targeting human telomere repeat was transfected together with dCas9 (+dCas9, left panel) or without dCas9 (–dCas9, right panel). The mCherry-TRF1 was co-transfected to label telomeres. b Representative images of the negative controls (with control gRNA and without gRNA) for different CRISPR/dCas9 labeling systems. c The percentages of cells having dCas9/gRNA foci in all GFP positive cells (N ≥ 30) were compared for difference labeling systems. Negative controls include without dCas9, with control gRNA, and without gRNA (–gRNA). d Quantification of telomere labeling specificity, in the condition with (upper panel) and without dCas9 (lower panel), based on co-localization with mCherry-TRF1 signals