Testicular cytosol factors inhibit the binding of steroid-receptor complexes to chromatin

Impaired spermatogenesis is not an obligate expression of receptor-defective androgen resistance

We are studying a man who presented at age 21 years with severe extragenital subvirilization despite high-normal to above-normal levels of plasma testosterone for at least 5 years. At puberty, his penis, scrotum, and testes matured normally, and he did not develop gynecomastia; however, his voice, muscularity, and facial, sexual, and body hair remained immature. A 2.5-ml ejaculate yielded normal results for sperm density, morphology, and motility. Because persistent undervirilization was emotionally disabling, he has received pharmacologic doses of testosterone enanthate intramuscularly for 3.5 years. The treatment has improved his virilization and masculine self-image substantially, and his semen analysis has remained well within the normal range. The androgen receptor in his genital skin fibroblasts has a distinctively mutant phenotype: it has a low affinity (increased apparent equilibrium dissociation constant, Kd) for 5 alpha-dihydrotestosterone and two synthetic androgens, mibolerone (MB) and methyltrienolone (MT), and its binding capacity (Bmax) is normal for the other two ligands, but questionably low for MT. In addition, it up-regulates its activity normally in response to prolonged incubation with androgen, and its androgen-receptor complexes are not thermolabile. Our study of this man permits two conclusions: impaired spermatogenesis is not the irreducible expression of receptor-defective androgen resistance in man; and androgen pharmacotherapy may be remedial for those in whom extragenital subvirilization is emotionally costly and subnormal spermatogenesis is not an inevitable side effect of such therapy.

Evidence for a Leydig cell progesterone receptor in the rat

Tritiated promegestone [3H] R 5020 is bound with high affinity by charcoal-treated cytosol prepared from purified Leydig cells. The binding is characterized by high affinity (Kd = 2 x 10(-9) M) and specificity (R 5020 = progesterone greater than testosterone = dehydrotestosterone greater than hydroxyprogesterone greater than cortisol = dexamethasone greater than estradiol) appropriate for progesterone receptors. In vitro, progestin-bound cytosol was quantitatively translocated to nuclei fractions, only if cytosol samples were previously labeled at 25 degrees C. However no translocation of binding activity was observed when previous cytosol labeling was done in the presence of sodium molybdate. Effects of glucocorticoids, androgens and estrogens on the Leydig cell are well documented, the demonstration of a putative progesterone receptor raises the possibility of direct effect of progesterone on the Leydig cell.

Suppression of steroid receptor-chromatin interaction by inhibitors present in ammonium sulfate-fractionated rat testicular androgen receptor preparations

Tritiated androgen receptor complex was partially purified by ammonium sulfate precipitation at 15 to 37% saturation from rat testicular or prostatic cytosols. A greater amount of prostatic tritiated androgen receptor complex bound to rat Sertoli cell chromatin than tritiated testicular androgen receptor complex. However, the testicular androgen receptor complex was more potent in competing for binding of either tritiated androgen receptor complex preparation to the Sertoli cell chromatin. Combining equal amounts of tritiated testicular and prostatic androgen receptor complexes resulted in lower binding than that observed with tritiated prostatic androgen receptor complex alone, while doubling the concentration of tritiated prostatic androgen receptor complex led to a 2-fold increase in binding. It is conceivable that the partially purified testicular androgen receptor complex preparations contain factor(s) that inhibit the binding interaction of tritiated androgen receptor complex with chromatin, while there is no evidence for the presence of such inhibitors in tritiated prostatic androgen receptor complex preparations. Fractionation of testicular cytosol on DEAE-cellulose yielded a flow-through fraction with inhibitory activity and a bound fraction containing tritiated androgen receptor complex that was eluted with 0.3 M KCl and also showed inhibitory activity. These factors also inhibited the binding of tritiated estradiol receptor complex to chromatin. They were non-dialyzable and their inhibitory effect was abolished after heating at 60 C for 30 minutes. It is concluded that ammonium sulfate-fractionated rat testicular androgen receptor complex preparations contain inhibitors of steroid receptor-chromatin interaction. The inhibitory factors can be fractionated into two distinct fractions by DEAE-cellulose column chromatography. They are nondialyzable and heat-labile. The precise chemical nature of the postulated inhibitor(s) remains to be determined.