Fig. 5: G4switch optically controls transcription in living cells.
From: Optical control of gene expression using a DNA G-quadruplex targeting reversible photoswitch
a, Schematic workflow of G4switch-mediated optical control of G4-containing gene expression profiled by SLAM-seq. U2OS cells were treated with 9 or DMSO control for 30 min in the dark or under indicated illumination conditions, followed by 4sU labelling over 60 min. RNA was extracted, and the abundance of newly synthesized RNAs was quantified by analysing T > C conversions through the SLAM-seq protocol. b, Stacked bar plot showing the overlap of downregulated genes by trans-9 (upon 405 nm illumination) and cis-9 (in the dark) with the corresponding Chem-map sites. Genes with Chem-map binding sites are shown in blue, while genes without Chem-map binding signals are shown in grey. Four independent biological replicates were performed. c, Images showing light-dependent spatial control of U2OS cell proliferation with 9 compared with DMSO control within the same 6-well plate. Half of the plate was covered with a black mask before pulsed 405 nm illumination for 72 h, followed by crystal violet staining and imaging. Representative images from one out of three independent biological replicates with similar results are shown. d, Bar plot showing quantification of cell viability relative to DMSO treatment in the dark from c. Results are shown as mean ± s.d. from three independent biological replicates (n = 3).
