Specific transcription in chicken liver chromatin by endogenous RNA polymerase II. Comparison of an estrogen-inducible gene with a constitutively expressed gene.

We have developed a system for the in vitro transcription of specific genes in rooster liver chromatin by endogenous RNA polymerase II that maintains the specificity of transcription in vivo. Radioactive transcripts synthesized in vitro were identified and quantitated by hybridization to a vast excess of cloned cDNA. The cDNA preparations employed corresponded to vitellogenin mRNA, the synthesis of which is responsive to estrogen stimulation in vivo, and chicken serum albumin mRNA, the synthesis of which is not significantly affected by estrogen stimulation in vivo. Comparing the pattern of transcription of the albumin and vitellogenin genes in chromatin from the liver of the normal rooster with the pattern in chromatin from the liver of the estrogen-stimulated rooster, we found that prior estrogen treatment of the rooster is attended by a slight decrease in the differential rate of transcription of the albumin gene and approximately a 10-fold increase in the differential rate of transcription of the vitellogenin gene. Because this pattern of transcription reflects the estrogen-induced changes in transcription observed in vivo, chromatin preparations from the livers of normal and estrogen-stimulated roosters can be used to investigate regulation of specific gene transcription at the molecular level in vitro.