Fig. 6: Narta can induce high-density assembly of coactivators at target sites.

a, c, d Left, representative images to show the co-localization between coactivators (MED1, p300, or BRD4) and nascent RNAs (labeled by stdMCP-tdTomato) produced by miniCMV. Right, line scan of the relative fluorescence intensity indicated by the dotted lines in the left panel. In a stdMCP-PH was transfected to induce Narta activation, while stdPCP-PH tranfection was used as the negative control. In d, f the expression of stdMCP-PH was induced by the addition of Dox. MED1 was detected by antibody, while p300 and BRD4 were endogenously tagged with HaloTag. Scale bar, 10 μm. b, e, f, Left, total intensity of activator reporters (MED1-Alex647, HaloTag-p300 and HaloTag-BRD4, respectively) enriched at visible miniCMV transcribing loci. Right, quantifications showing the percentage of visible stdMCP-stdTomato spots (representing active mimiCMV loci) which were co-localized with enriched signal of coactivators (MED1, p300 or BRD4). n = 3 biological replicates. g, h Scatter plots of nascent RNA level (x-axis) and the enriched signal of co-activator (p300 or BRD4, y-axis). Gray line denotes the linear fit. R represents the correlation coefficient. Each dot represents a single cell. n = 50 cells. i Quantifications of BRD4-HaloTag signal (right), nascent RNA production (total intensity of individual stdMCP-tdTomato foci, left), and the co-localization between nascent RNA and BRD4 (n = 3 independent experiments by examining 30 cells in each repeat) at active miniCMV loci under different conditions. Dox was added to induce Narta activation for 12 h. Together with Dox, DMSO, A-485 or JQ1 was added into the medium. P-value was analyzed by One-way ANOVA with Tukey’s post hoc. j Quantifications of miniCMV-BFPTriTag expression levels in cells transfected with stdPCP-PH (negative control), stdMCP-p300 or different stdMCP-TFs (n = 100 cells). All histograms in Fig. 6 are displayed as mean ± s.e.m. Source data are provided as a Source Data file.