Early androgen action in kidney of normal and androgen-insensitive (tfm/y) mice. Changes in RNA polymerase and chromatin template activities.

Intranuclear accumulation of testosterone was compared with early changes in transcriptional events in kidneys from normal female and androgen-insensitive (tfm/y) mice. Following a subcutaneous injection of [3H] testosterone, total nuclear uptake of the steroid was maximal at 30 min and declined to about 40% of the peak value by 4 h after hormone administration. After a single subcutaneous dose of testosterone, RNA polymerase activity assayed in intact nuclei in the presence of Mg2+ and alpha-amanitin (nucleolar RNA polymerase I), as well as the enzyme activity sensitive to low concentration of the toxin (nucleoplasmic RNA polymerase II), increased within 15 min and attained peak values at 2 and 1 h, respectively. The activity of both polymerases declined almost to the control level by 4 h and then increased again with a second peak at 20 and 12 h for RNA polymerase I and II, respectively. Similarly, the template capacity of mouse kidney chromatin, as measured with mammalian RNA polymerase II, increased by 15 min, reached a peak at 1 h and returned to control level by 4 h following hormone treatment. A second dose of testosterone given at the nadir (4 h) was not capable of stimulating renal chromatin template activity significantly as compared to the effect observed after the initial hormone treatment. Contrary to the testosterone-stimulated changes in transcriptional events observed in normal female mice, androgens elicited no response in androgen-insensitive tfm/y mice, animals lacking cytosol androgen receptors. These results strongly support the contention that hormone-specific receptors are obligatory to steroid-mediated modifications in gene transcription.