FIG. 4.
Dysregulation of chromatin structure in Dnmt1c/ps embryos. (A and B) Immunofluorescence staining of embryonic cells isolated from wild-type (WT) and mutant embryos at E9.5 with specific antibodies to HP1β (A) and H3K9me3 (B). Nuclei were stained with DAPI. The upper panels are low-magnification images (conventional microscopic images), and the lower panels are high-magnification images (deconvolution images). Percentages of cells showing the decreased heterochromatin signal (left) and diffuse staining pattern (right) of HP1β are shown (A). For H3K9me3 staining, interphase (left) and mitotic (right) nuclei are shown (B). (C) Immunoblot analysis of HP1β in the Triton-resistant and Triton-extracted fractions of embryonic cells. PCNA was used as the control for the Triton-extracted fraction. (D, E) Immunostaining analysis of acetylated H4 in embryonic cells. A small population of cells in both the Dnmt1c/c and Dnmt1c/ps embryos had abnormally hyperacetylated histone H4 (D). An abnormal association of HP1β proteins with mitotic chromosomes with hyperacetylated histone H4 was observed (E). Scale bars, 10 μm.