Sertoli Cell Nuclear Transcriptional Activity: Stimulation by Follicle-Stimulating Hormone and Testosterone in Vitro*

Abstract

RNA polymerase activities were characterized in intact nuclei obtained from cultured rat Sertoli cells. The activities of α-amanitin-resistant RNA polymerases I and III were identical when measured in low or high ionic strength (0.05 or 0.25 M) ammonium sulfate in the presence of MnCl2 or MgCl2, with a divalent cation optimum of 1.6 mM. α-Amanitin-sensitive RNA polymerase II was most active in 0.25 M ammonium sulfate and 1.6 mM MnCl2. The apparent Km of RNA polymerase II activity in intact nuclei for UTP was 0.016 mM in 0.05 M ammonium sulfate and 0.037 mM in 0.25 M ammonium sulfate. The apparent Km values for total polymerase activity were 0.008 and 0.036 mM at low and high ionic strengths, respectively. These data indicate that Sertoli cell RNA polymerase activities have catalytic properties characteristic of eukaryotic polymerase activities in general. FSH stimulated Sertoli cell RNA polymerases I and III after 30–45 min of incubation. RNA polymerase II activity was maximally stimulated by 30–45 min. The addition of testosterone to cultures of Sertoli cells from 25-day-old rats resulted in the biphasic preferential stimulation of polymerase II activity. The activity increased 2-fold within 15 min, then partially declined, and increased again at 3 and 6 h. The stimulation was androgen specific and dose dependent. Whereas 0.1 nM testosterone did not increase polymerase II activity, 1 nM testosterone or dihydrotestosterone was stimulatory. Methyltrienolone (R1881; 17β-hydroxy-17-methylestra-4,9,ll-trien-3- one), a synthetic androgen, also increased polymerase II activity. Progesterone, 17α-hydroxyprogesterone, and estradiol had no effect at a concentration of 1 nM. These data constitute the first demonstration of the direct effect of androgens on the transcriptional process in the Sertoli cell. (Endocrinology108: 1020, 1981)