Fig. 3

Myotubes had fewer PML bodies than myoblasts and the structure of most PML bodies was not affected by DUX4-FL expression. a Human myoblasts from a healthy donor typically had 10 to 20 or sometimes more PML-positive structures (green). b Nuclei in myotubes typically had four to eight PML bodies. c Quantitation of PML bodies in myoblasts (light gray bars) and myotubes (dark gray bars) in healthy control, MDC1A, DUX4-FL-negative, and LGMD2D myogenic cells. All cultures showed similar decreases in PML body number in myotube vs. myoblast nuclei. Error bars = s.e.m. **P < 0.01 by t test, with all PML bodies counted in n = 50 nuclei. d Quantitation of the cross-sectional areas of PML bodies in myoblasts (light gray bars) and myotubes (dark gray bars) in healthy control, MDC1A, DUX4-FL-negative FSHD, and LGMD2D myogenic cells. All cultures showed no significant changes in PML body size in myotube vs. myoblast nuclei. Error bars = s.e.m. n.s. not significant (P > 0.05) by t test. Number of PML bodies measured as indicated on each bar. e–e” In most, but not all (see Fig. 4), nuclei with punctate DUX4-FL fluorescence, PML bodies showed minor or no disruption, and there was little overlap between DUX4-FL and PML fluorescence. Nuclei in myotubes are shown. Arrow = DUX4-FL-positive nucleus, asterisk = DUX4-FL-negative nucleus. f–f” DUX4-S was typically uniformly distributed within the nuclei, and expression of DUX4-S did not affect PML body morphology. Nuclei in myotubes are shown. Bar in a = 20 μm for a, b, f, and 15 μm for e