The action of estrogen and progesterone on the expression of the transferrin gene. A comparison of the response in chick liver and oviduct.

We present evidence that conalbumin and transferrin, synthesized in chick oviduct and liver, respectively, are products of the same gene, but the gene is regulated differently in the two tissues. Conalbumin mRNA was purified 500-fold from hen oviduct by a combination of immunoprecipitation of polysomes, oligo(dT) chromatography, and sucrose gradient centrifugation. A cDNA complementary to conalbumin mRNA was synthesized and used to demonstrate that by size and hybridization properties, conalbumin mRNA in the oviduct is identical with transferrin mRNA in the liver. Polyacrylamide gel analysis suggests that both mRNAs have an apparent molecular weight of 1 x 10”. In addition, hybridization of conalbumin cDNA to chick DNA indicates there are 1 to 2 gene copieslhaploid genome. The effects of estrogen and progesterone on the expression of this gene in chick oviduct and liver were examined. Both steroids induced a marked stimulation of conalbumin synthesis and after 96 h of hormone, the rate was elevated 6to S-fold with estrogen and 5to &fold with progesterone. In both cases, the response could be accounted for by a rapid increase in conalbumin mRNA sequences. Although estrogen also stimulated transferrin synthesis, the effect was much less pronounced with only a 1.5to Z-fold stimulation after 96 h of hormone, and there was a lag in the appearance of transferrin mRNA. Progesterone had no effect on transferrin synthesis. The cell-specific regulation of this gene in the liver and oviduct is particularly interesting because both are estrogen-responsive tissues induced by the hormone to synthesize egg yolk and egg white proteins, respectively. This system may provide a model for exploring the differential programming of a specific gene during development and differentiation.