RNA synthesis and histone acetylation during the course of gene activation in lymphocytes.

Abstract

Human and equine lymphocytes increase their rates of RNA synthesis within minutes after exposure to phytohemagglutinin (PHA). Histone acetylation (but not histone synthesis) is greatly increased in lymphocytes responding to PHA. The increase in acetylation of the basic proteins of the chromosomes appears to precede the increase in nuclear RNA synthesis. Equine polymorphonuclear cells treated with PHA decrease their rates of RNA synthesis, and histone acetylation is curtailed. The results are consistent with the view that histone acetylation signals a change in the fine structure of the chromatin and in the capacity of the DNA to serve as a template for RNA synthesis.