The control of the synthesis and secretion of plasminogen activator by rat sertoli cells in culture

Abstract

Sertoli cells in primary cultures produce plasminogen activator activity, and release it into the medium at rates greatly influenced by a variety of factors, including cell density, the presence of hormones, incubation temperature and duration of culture. In Sertoli cells maintained in culture in the presence of dibutyryl cAMP, the amounts of plasminogen activator activity secreted per cell were maximal at cell densities up to 2.5 μg DNA/cm 2 (350 units/μg cell DNA), and declined to 40 units/μg cell DNA at a density of 22 μg DNA/cm 2. Concentrations of follicle-stimulating hormone (FSH) required to elicit half-maximal stimulation of the production of plasminogen activator activity were 0.37 μg/ml for oFSH-NIH S12 and 8 ng/ml for the more purified oFSH-S1528C2. The ED 50 for dibutyryl cAMP was found to be 0.08 mM. Addition of an inhibitor of phosphodiesterase (3-isobutyl-l-methylxanthine) enhanced the formation of plasminogen activator by cells cultured in the presence of FSH. Addition to the culture medium of testosterone, epidermal growth factor, insulin, human chorionic gonadotropin or prostaglandins (E 1, E 2 or F 1α) did not result in increased production of PA activity by Sertoli cells. Cells in culture for as long as 14 days remained responsive to FSH or dibutyryl cAMP. Increases of cellular levels of plasminogen activator became evident within 2–4 h after addition of either FSH or dibutyryl cAMP to the medium. The stimulation by FSH or dibutyryl cAMP of the production of plasminogen activator activity was shown to be dependent upon de novo synthesis of RNA and protein. Levels of enzyme activity released by Sertoli cells maintained in culture for 48 h at 37°C were approx. 50% higher than plasminogen activator released by cells cultured at 32°C. The control of the production of plasminogen activator activity by Sertoli cells was discussed in relation to the control of plasminogen activator production by granulose cells, and the possible role of plasminogen activator in gonadal functions.