Quantitative analysis of histone H1 degrees protein synthesis in HTC cells.

H1 degrees, a member of histone H1 family associated with cell growth arrest and differentiation, is barely expressed in most mammalian cells in culture. Depending on the cell type, serum deprivation or drugs, such as sodium butyrate, significantly increase H1 degrees mRNA level and H1 degrees protein accumulates. However, probably because of a lack of a simple quantitative procedure, little is known about the relationship between H1 degrees mRNA content and its effective translation rate.

A protein phosphatase is involved in the inhibition of histone deacetylation by sodium butyrate.

Treatment of cells with sodium butyrate is known to increase histone acetylation by inhibiting deacetylases. Here we have observed, in cultured hepatoma cells, that the potent serine-threonine phosphatase inhibitors, okadaic acid or calyculin A, inhibited phosphatase activity and concomitantly decreased the histone acetylation classically maintained by sodium butyrate. These results suggest that a protein phosphatase may mediate the sodium butyrate effect on deacetylases.

The effects of sodium butyrate on transcription are mediated through activation of a protein phosphatase.

In this study we have investigated the molecular mechanism by which sodium butyrate modulates gene expression when added to cultured cells. As a model system we used hepatoma tissue culture cells in which sodium butyrate treatment increases histone H1(0) mRNA level and decreases c-myc mRNA level. Because we observed that stimulation of histone H1(0) gene expression could take place in the absence of protein neosynthesis, we hypothesized that sodium butyrate induced a post-translational modification of a factor involved in the transcription process.

Characterization, purification and cDNA cloning of a rat perchloric-acid-soluble 23-kDa protein present only in liver and kidney.

A novel protein was extracted with 5% perchloric acid from rat liver and kidney. It is absent from other rat organs. Its apparent molecular mass is 23 kDa as determined by HPLC gel filtration.

[Molecular and cellular action of butyrate].

Butyrate has a dramatic effect on transformed cells in culture. This effect disappears as soon as butyrate is removed from the medium. The other short chain fatty acids are much less effective.