Histone acetylation in synchronized mammalian cell cultures

Abstract

Synchronized cultures of mammalian cells were labeled with [ 3H]acetate. Incorporation of labeled acetate into histone fractions was followed through the cell cycle from late G 1, through S and G 2, into early M. The acetate contents of histone fractions F2a, F2b and F3 rose rapidly to a maximum in late S, coincident with the termination of DNA synthesis, and declined rapidly thereafter. The acetate content of histone fraction F1 rose to a maximum in mid-S, coincident with maximal DNA synthesis, and decreased rapidly thereafter. Fractions F1 and F2b lost the majority of their incorporated acetate, while fractions F2a and F3 retained approximately half their incorporated acetate. Evidence is presented for differential acetylation of histone fractions, for a temporal coupling of histone biosynthesis and acetylation and for a differential turnover of histone fraction acetyl groups.