Induction of histone hyperacetylation correlates with stimulation of HbF synthesis.

K562 cells were treated with the HDAC inhibitors TSA, MS-275, apicidin, or DMSO (co) for 1 hour, respectively. Histone proteins were prepared by acid extraction, and acetylation of histone H4 was determined by Western blot analysis by using a specific antiacetyl H4 histone antibody (top panel). Coomassie staining of the corresponding gel shows equal loading (20 μg) of histone proteins (H2A, H2B, H4) on each lane (middle panel). Bottom panel shows stimulation of HbF synthesis by the respective HDAC inhibitor after 4 days of treatment. H4 ac indicates acetylated histone H4; H2A, H2B, H4; histone proteins H2A, H2B, H4.