Abstract
Mouse neuroblastoma cells treated with millimolar concentrations of butyrate adjusted their
recipe of histone HI subfractions over the course of several days, eventually attaining an enrichment of about
5-fold in HI0. This adjustment in the proportions of the Hi’s, which was essentially complete by 4 days,
was brought about by changes in synthesis and turnover that were different for each of the three HI
subfractions. As the cells stopped dividing, the synthesis of all histones slowed substantially, but core histones
were affected more than the Hi’s. Transiently, therefore, there was an overproduction of Hi’s relative to
core histones, but the excess HI was eventually removed by turnover. The very slow turnover of HI0 and
the rapid turnover of Hlc were not substantially affected by butyrate treatment, but the turnover of Hlab
was greatly accelerated by butyrate. Acetylation of the core histones was not necessary for maintenance
of elevated HI0 levels in the noitdividing cells, although we did not rule out its involvement in the initial
accumulation of HI0.