Nuclear levels and patterns of histone H3 modification and HP1 proteins after inhibition of histone deacetylases

Abstract

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.

Histone deacetylase inhibition redistributes topoisomerase IIb from heterochromatin to euchromatin

“…4,49 In human cells, HP1α gives the most robust pericentromeric staining pattern of the three HP1 species. 36,51 When we compared the distribution of HP1α to that of topoisomerase IIβ, HP1 substantially coincided with the areas of brightest topoisomerase IIβ signal (Fig. 8C).…”

“…HDACI treatment leads to global changes in histone acetylation levels, including hyperacetylation of heterochromatin and redistribution of the non-histone heterochromatin protein HP1. [34][35][36][37] It follows that this may affect the distribution of topoisomerase II in the interphase nucleus. Indeed, enzymatically active topoisomerase IIα is concentrated in heterochromatin in mid-late S-phase in HeLa cells and is delocalized by the HDACI TSA.…”

“…In mouse cells under these conditions, pericentromeric heterochromatin relocates from a largely perinucleolar to a more peripheral distribution and in mouse and human cells, HP1 proteins become dissociated from heterochromatic regions. 34,36 In the light of this HDAC-mediated chromatin remodelling, and the role of topoisomerase IIβ in sensitization of cells to topoisomerase poisons by HDAC inhibitors, we hypothesized that HDAC inhibitors such as TSA or VPA may alter the subnuclear distribution of topoisomerase IIβ. This, either directly or through increased accessibility of decondensed chromatin could lead to increased cytotoxicity associated with topoisomerase poisons.…”

Somatic Nucleus Reprogramming Is Significantly Improved by m-Carboxycinnamic Acid Bishydroxamide, a Histone Deacetylase Inhibitor

“…Apart from being involved in the control of gene expression, the level of acetylation of the chromatin also plays a role in the spatial configuration of the chromatin (28,29). During normal development, a dynamic reorganization of the heterochromatin occurs that seems to be required for subsequent development to occur (5).…”

Histone Phosphorylation and Pericentromeric Histone Modifications in Oocyte Meiosis

“…36 TSA treatment could enhance the level of dimethylated lysine 4 on H3 (dime-H3/K4) at nuclear periphery in several cell lines. 37 However, up to now, there has not been a thorough examination of the effects of TSA on distinct epigenetic modifications of pericentromeric heterochromatin using immunocytochemistry either in mitosis or meiosis.…”