Increased chromatin dynamics by RNAPII inhibitors. (A) MSD plots (±SD among cells) of nucleosomes in the RPE-1 cells treated with RNAPII inhibitors, α-AM (pink), DRB (purple), and ActD (brown). The controls are DMSO (gray), MQ (light blue), or untreated (black). For each condition, n = 20 cells. Note that the inhibition of RNAPII increased the chromatin dynamics, except for ActD. ***, P < 0.0001 by the Kolmogorov–Smirnov test for untreated control versus DRB (P = 1.4 × 10−7), for untreated control versus α-AM (P = 1.0 × 10−8), and for untreated control versus ActD (P = 9.5 × 10−6). (B) Chromatin heat maps of the nuclei treated with (right) and without α-AM (left): Larger chromatin movement appears as more red (or hot), and smaller movement appears as more blue (or cold) pixels. Note that the heat map of the nucleus with α-AM turned more red. Bar, 5 μm. (C) MSD plots (±SD among cells) of single nucleosomes in RPE-1 cells treated with RNAPII inhibitor (α-AM, DRB) or without inhibitors (control) from 0.05 to 3 s. For each sample, n = 20 cells. The inhibitor treatments increased chromatin dynamics with less constraint. The plots were fitted as a subdiffusive curve: MSD = 0.018t0.28 in untreated cells; MSD = 0.022t0.26 in DRB-treated cells; MSD = 0.025t0.28 in α-AM–treated cells. Rc: 141 ± 19.2 nm in untreated cells, 149 ± 20.4 nm in DRB-treated cells, and 164 ± 22.0 nm in α-AM–treated cells. Rc values between untreated control and α-AM–treated cells are significantly different: P = 0.018 by the Kolmogorov-Smirnov test.
