Alterations in histone phosphorylation in HL-60 cells specific to monocytic differentiation

In order to examine the role of histone phosphorylation in regulation of the pathway of HL-60 cell differentiation, cells were labelled with [32P]phosphoric acid and histones fractionated by two-dimensional polyacrylamide gel electrophoresis. The monocytic inducer 12-O-tetradecanoylphorbol-13-acetate (TPA) was found to specifically stimulate phosphorylation of histone H2B in a concentration-dependent manner. At a concentration of 100 mM, H2B phosphorylation was stimulated 2.3-fold after 4 h. A second monocytic inducer 1,25-dihydroxy-cholecalciferol (100 nM) also induced phosphorylation specifically in histone H2B. In contrast, the granulocytic inducers DMSO (1.5%) or retinoic acid (1 microM) did not increase phosphorylation in any histone species.