Enhanced transcription of rRNA genes by purified androgen receptor complexes in vitro

Androgens stringently regulate the concentrations of the polyamines, spermine and spermidine, in rat ventral prostate. The intracellular distribution of the polyamines is also dependent on the androgenic milieu; a small proportion of polyamines is associated tightly with the nucleus. Soluble nucleolar chromatin contains RNA polymerase A and protein kinase activities, both of which are regulated by androgens and markedly stimulated by polyamines. It remains to be established whether the polyamines modulate these enzyme moieties directly, or whether the phosphorylation of other nucleolar proteins plays a crucial role in the androgenic regulation of rRNA synthesis. Using a protocol centered on affinity chromatography, the purification of the androgen receptor protein to a state approaching homogeneity has been accomplished. The purified receptor stimulates the RNA polymerase A and protein kinase activities associated with prostate nucleolar chromatin. The significance of these findings in the light of correct concepts of steroid hormone action is discussed.