Histone acetylation regulates intracellular pH

Differences in global levels of histone acetylation occur in normal and cancer cells, although the reason cells regulate these levels has remained unclear. Here we demonstrate a role for histone acetylation in regulating intracellular pH (pHi). As pHi decreases, histones are globally deacetylated by histone deacetylases (HDACs) and the released acetate anions are co-exported with protons out of the cell by monocarboxylate transporters (MCTs), preventing further reductions in pHi. Conversely, global histone acetylation increases at more alkaline pHi, such as when resting cells are induced to proliferate. Inhibition of HDACs or MCTs decreases acetate export and lowers pHi, particularly compromising pHi maintenance in acidic environments. Global deacetylation at low pH is reflected at a genomic level by decreased abundance and extensive redistribution of acetylation at promoters and intergenic regions. Thus acetylation of chromatin functions as a rheostat to regulate pHi with important implications for therapeutic use of HDAC inhibitors. To investigate the redistribution of H4K16ac throughout the genome upon treatment at pH 6.5