Specificity and nature of the rapid steroid-stimulated increase in Sertoli cell nuclear RNA polymerase activity.

Overview

This report explores the ability of various steroids to rapidly stimulate Sertoli cell RNA polymerase II activity and to compete with [3H]-androgens for nuclear and cytosol binding sites. Nuclear RNA polymerase II activity was significantly stimulated by a 1 nM concentration of the androgenic compounds testosterone, dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one). R1881 (methyltrienolone) and 5 alpha, 17 beta-diol and also by the potent progestins 6 alpha methylprogesterone and R5020 (17,21-dimethyl-19-nor-4-pregna-3,20-dione). Progesterone, 17 alpha-hydroxyprogesterone, estradiol, androsterone, and 5 alpha-androstan-3 beta, 17 beta-diol were ineffective at 1 nM. Cytosol binding and nuclear accumulation of [3H]-androgen was effectively reduced by 100 fold molar excess of those androgens and progestins which stimulated RNA polymerase II activity. These data suggest that androgens and progestins bind to at least some of the same proteins in the Sertoli cell and may elicit the rapid stimulation of RNA polymerase II activity via a common mechanism. Agarose gel electrophoresis of the nuclear RNA synthesized as a result of exposure to testosterone indicated that is was heterodisperse and in part polyadenylated. Electrophoresis of the poly A+-RNA demonstrated that testosterone administration increased the incorporation of [3H]-UTP into RNA that was larger than 28 S.