Estradiol enhanced acetylation of nuclear high mobility group proteins of the uterus of newborn guinea pigs

The effect of estradiol on the acetylation of nuclear high mobility group (HMG) proteins in the uterus of newborn (3 days old) guinea pigs was studied "in vivo" and in tissue slices. In the "in vivo" studies after subcutaneous injection of 5 mCi 3H]-acetate there is a rapid (20 min) uptake of radioactive acetate in the HMG-1, HMG-2, HMG-14 and HMG-17 high mobility group proteins. In parallel studies, after administration of the same quantity of 3H]-acetate plus 20 micrograms of estradiol (E2), a selective increase in the acetylation of HMG-14 protein is observed. The preferential acetylation of HMG-14 can also be demonstrated in uterine tissue slices 20 minutes after exposure to the hormone (5 x 10(-8)M). In conclusion, the present data suggest that the acetylation of HMG proteins, in particular HMG-14, and like that of nucleosomal "core" histones, is an early event in gene activation by estradiol.