Figure 1.

GSK126 and SAHA disrupt chromosome X gene dosage compensation in human female cells. A, Total H3K27me3, H3 acetylation, and histone H3 protein levels of IMR-90s treated with various concentrations and combinations of epigenetic inhibitors, GSK126 and SAHA, or DMSO alone as the control. Total histone H3 was used as a loading control. B, Maximum intensity projections of H3K27me3 (green) and chromosome X (red) localization in IMR-90 nuclei (blue). Insets show enlarged nuclei, arrows highlight location of the Xi. C, Distribution display of 3-dimensional volumetric measurements of H3K27me3 signal over total Xi signal for either DMSO or 2 μM GSK126 + 5 μM SAHA treatment (n = 130 nuclei, 65 nuclei per condition). *P < .05, **P < .01, ***P < .001, Student t test. D, Quantitative PCR analysis of X-linked genes with either DMSO treatment or 2 μM GSK126 + 5 μM SAHA treatment. Values presented as mean (standard deviation) of 3 technical replicates. *P < .05, **P < .01, ***P < .001, Student t test. Relative expression levels of genes in DMSO-treated cells indicated under graph. E, Schematic diagram of chromosome X, with corresponding positions of X-linked genes analyzed in (D) as well as the Xist gene locus. Significantly upregulated genes (green) and significantly downregulated genes (red). ‡Genes identified to escape XCI in human hybrid fibroblasts,¹⁷ and frequency of escape listed in parenthesis. DMSO, dimethyl sulfoxide; PCR, polymerase chain reaction; SAHA, suberoylanilide hydroxamic acid; XCI, X-chromosome inactivation; Xi, inactive X.