Acetylation and phosphorylation of nuclear proteins from growing or dividing rat ventral prostate cells.

Abstract

Acetylation and phosphorylation of nuclear histone and nonhistone proteins from rat ventral prostate cells undergoing cellular hypertrophy (growth) or cellular hyperplasia (replication) were compared in minced ventral prostate incubated for 1 h with 32PO4 and [3H]acetate.Under these conditions, phosphorylation of unfractionated prostate histones from hormone-treated animals was increased, but acetylation was not. When radioactive histones from the four experimental groups were separated by polyacrylamide gel electrophoresis, evidence for differential labelling of individual histones, especially acetylated or phosphorylated histones F1 and F2a2, was obtained. This was also true of histones labelled with radioactive amino acids. These differences were more marked with histones from replicating cells.Phosphorylation of prostate nuclear nonhistone proteins from hormone-treated rats was greater than their controls. Proteins of intermediate molecular weight (20–45 × 103) were most highly phosphorylated; nuclear extracts from replicating (C7T2) cells contained additional labelled higher molecular weight proteins and fewer lower molecular weight proteins (< 20 × 103), compared with hypertrophic (C3T3) cells. Previous treatment with testosterone propionate increased the apparent acetylation of nonhistone proteins, but its marked inhibition by puromycin and resistence to hydrolysis suggests that much of this incorporation occurred during their biosynthesis, and did not represent covalent modification of previously synthesized proteins.