Effects of estrogen on gene expression in the chick oviduct. Control of ovalbumin gene expression by non-histone proteins.

Chromatin was isolated from the oviducts of chicks which had either received diethylstilbestrol stimulation for 14 days (stimulated chromatin) or been treated and then withdrawn from hormone administration (withdrawn chromatin). These chromatin preparations were dissociated and then reconstituted in the presence of various non-histone protein fractions. cDNAov was used as a probe for measuring the level of mRNAov sequences synthesized in vitro from various reconstituted chromatins. Our results indicate that extractable non-histone proteins from stimulated chromatin are capable of activating the in vitro transcription of the ovalbumin gene when included in the reconstitution of withdrawn chromatin. On the other hand, addition of extractable non-histone proteins from withdrawn chromatin to stimulated chromatin does not affect the synthesis of mRNAov sequences. Therefore, the extractable non-histone proteins from stimulated chromatin contain a positive regulator(s) which controls the in vitro expression of the ovalbumin gene.