Inducibility of heat shock polypeptides in cells containing hyperacetylated histones

We have examined the effect of sodium butyrate on the levels of histone acetylation, the pattern of protein synthesis and the inducibility of heat shock polypeptides (hsps) in cultured trout fibroblasts. Maximal levels of histone acetylation are achieved upon treatment of these cells with 5 mM butyrate for 24 h. No significant changes in the pattern of protein synthesis, as detected by two-dimensional gel electrophoresis, are apparent under these conditions, although changes in the levels of three polypeptides are seen at shorter times of exposure to butyrate. Heat shock polypeptides are inducible at normal levels in butyrate-treated cells. This is in contrast to the ability of butyrate to inhibit the activation of steroid-inducible genes in some systems.