Figure 5. H4K20me3 Redistribution in Mecp2-Null Nuclei is a Cell Type Specific Event.

Panels A-D represent fluorescence images taken from a volume rendering through the suprapyramidal dentate granule cell layer. (A) DAPI staining. Scale bar, 1 μm. (B) Immunostaining for MeCP2-GFP identifies left neuron as WT and right neuron as Mecp2-null. (C) Immunostaining for H4K20me3. (D) Merged image showing H4K20me3 distribution (red) relative to major satellite FISH signal (green). (E) Scatter plot showing the percentage of total nuclear H4K20me3 within the major satellite threshold (mean ± SD). There is a significant redistribution of H4K20me3 into pericentromeric heterochromatin after loss of MeCP2 (WT, 14.0 ± 1.8, n = 15 nuclei from two mice), (null, 27.0 ± 2.1, n = 15 nuclei from two mice). Unpaired t test, p < 0.0001. (F) Scatter plot showing the percentage of total nuclear DAPI pixel intensity located within the heterochromatin threshold (mean ± SD). (WT, 24.7 ± 2.7), (null, 28.5 ± 1.8). Unpaired t test, p < 0.0001. Panels G-J represent fluorescence images taken from a volume rendering through the cerebellar granule cell layer. (G) DAPI staining. Scale bar, 1 μm. (H) Immunostaining for MeCP2-GFP distinguishes between WT and MeCP2-null granule cells. (I) Immunostaining for H4K20me3. (J) Merged image showing H4K20me3 distribution (red) relative to major satellite FISH signal (green). (K) Scatter plot showing the percentage of total nuclear H4K20me3 within the major satellite threshold (mean ± SD). (WT, 30.7 ± 2.1, n = 17 nuclei from two mice), (null, 31.2 ± 1.8, n = 17 nuclei from two mice). Unpaired t test, p = 0.4075. (L) Scatter plot showing the percentage of total nuclear DAPI pixel intensity located within the heterochromatin threshold (mean ± SD). (WT, 56.2 ± 2.5), (null, 56.9 ± 3.0). Unpaired t test, p = 0.4526. See also Figure S4, Figure S5, and Movie S5.