Inhibition of histone deacetylation by butyrate induces morphological changes in Y79 retinoblastoma cells.

PURPOSE: Exposure of Y79 cells, a retinoblastoma cell line, to sodium butyrate, a histone deacetylase inhibitor, induces neuronlike morphological changes and apoptosis. To determine whether the effect of butyrate results from an inhibition of histone deacetylation, we examined the morphological changes, cell viability, and histone acetylation levels of Y79 cells induced by butyrate and trichostatin A (TSA), a specific inhibitor of histone deacetylases.
METHODS: Y79 cells cultured in a synthetic medium were exposed to butyrate or TSA, and the morphological changes and cell viability were followed. Actinomycin D was used to determine whether the morphological changes were transcription-dependent. The level of acetylated histone was determined by Western blotting and immunocytochemistry.
RESULTS: Butyrate and TSA induced morphological changes and apoptosis of Y79 retinoblastoma cells in a dose-dependent manner. The morphological changes were sustained and reversible with butyrate but were transient with TSA. Actinomycin D completely inhibited the morphological changes induced by butyrate and TSA. The elevation of histone H3 levels was sustained and reversible in butyrate but transient in TSA. The change in histone H3 acetylation levels preceded the morphological changes and apoptosis.
CONCLUSION: The induction of morphological changes by butyrate results from an inhibition of histone deacetylation and transcription.