The effects of the histone deacetylase inhibitors (HDACi) trichostatin A (TSA) 
and sodium butyrate (NaBt) were studied in A549, HT29 and FHC human cell lines. 
Global histone hyperacetylation, leading to decondensation of interphase 
chromatin, was characterized by an increase in H3(K9) and H3(K4) dimethylation 
and H3(K9) acetylation. The levels of all isoforms of heterochromatin protein, 
HP1, were reduced after HDAC inhibition. The observed changes in the protein 
levels were accompanied by changes in their interphase patterns. In control 
cells, H3(K9) acetylation and H3(K4) dimethylation were substantially reduced to 
a thin layer at the nuclear periphery, whereas TSA and NaBt caused the 
peripheral regions to become intensely acetylated at H3(K9) and dimethylated at 
H3(K4). The dispersed pattern of H3(K9) dimethylation was stable even at the 
nuclear periphery of HDACi-treated cells. After TSA and NaBt treatment, the HP1 
proteins were repositioned more internally in the nucleus, being closely 
associated with interchromatin compartments, while centromeric heterochromatin 
was relocated closer to the nuclear periphery. These findings strongly suggest 
dissociation of HP1 proteins from peripherally located centromeres in a 
hyperacetylated and H3(K4) dimethylated environment. We conclude that inhibition 
of histone deacetylases caused dynamic reorganization of chromatin in parallel 
with changes in its epigenetic modifications.