Fig. 2: Adriamycin forms complexes with chromatin condensates.
From: Chemical-induced phase transition and global conformational reorganization of chromatin
a Comparison of dynamics of two DNA-intercalating reagents, adriamycin and cisplatin, in mouse embryonic fibroblasts (MEFs). As revealed by Airyscan2 microscope, adriamycin entered nuclei exhibited the fibrous morphology, followed by a transition towards dense aggregates. Cisplatin was conjugated with Texas Red for visualization while adriamycin has intrinsic excitation wavelength at 514 nm. Arrows, large puncta which could possibly be heterochromatin. Scale bar, 10 μm. b FRAP analysis showed the material exchange of adriamycin within condensates. Scale bar, 10 μm. Signals were corrected for photobleaching using a similarly sized unbleached area and then normalized to the ratio between the average intensity of the pre-bleach images and the lowest post-bleach intensity. The signal intensities are presented as means +/− standard deviation (SD) (n = 10–15 cells per condition). c Adriamycin co-localized with condensed chromatin in U2OS and HCT116 cells. Adriamycin appeared fibrous or dotted at the 0.5 h time point, while the chromatin appeared homogenous. The co-localization became apparent at the 4 h time point. Scale bar, 10 μm. d Live imaging of the adriamycin–DNA condensates by the SIM super-resolution microscope. U2OS cells were incubated with 0.5 μM SiR-Hoechst overnight and treated with 1.5 μg/ml for 2 h before imaging. Scale bar, 10 μm. e Co-aggregated adriamycin and chromatin were reversible. U2OS cells were treated with 1.5 μg/ml adriamycin for 4 h, followed by drug removal for 12 and 24 h. The punctate pattern of adriamycin–DNA was almost completely disappeared after 24 h reversal. Scale bar, 10 μm. Quantification of % of punctate cells in each condition was performed on 3 separate fields (n = 3), each containing ~50 cells. Data are presented as means +/− SD. Ctrl, control; adria, adriamycin. Source data are provided as a Source data file. Experiments of (a) and (b) were repeated at least three times, and experiments of (c) and (e) were repeated twice with similar results.
