HORMONAL-REGULATION OF TISSUE-TYPE PLASMINOGEN-ACTIVATOR AND PLASMINOGEN-ACTIVATOR INHIBITOR TYPE-1 IN CULTURED MONKEY SERTOLI CELLS

Sertoli cells play a central role in the control and maintenance of sp ermatogenesis. Isolated Sertoli cells of mouse and rat testes have bee n shown to secrete plasminogen activator (PA) and a plasminogen activa tor inhibitor type-1 (PAI-1) in culture. In this study, we have invest igated the hormonal regulation of PA and PAI-1 activities in cultured monkey Sertoli cells. Sertoli cells (5x10(5) cells/well) isolated from infant rhesus monkey testes were preincubated at 35 degrees C for 16 h in 24-well plates precoated with poly(D-lysine) (5 mu g/cm(2)) in 0. 5 mi McCoy's 5a medium containing 5% of fetal calf serum and further i ncubated for 48 h in 0.5 mi serum-free medium with or without various hormones or other compounds, PA as well as PAI-1 activities in the con ditioned media were assayed by fibrin overlay and reverse fibrin autog raphy techniques respectively. The Sertoli cells in vitro secreted onl y tissue-type PA (tPA), no detectable amount of urokinase-type PA (uPA ) could be observed, Monkey Sertoli cells were also capable of secreti ng PAI-1, Immunocytochemical studies indicated that both tPA and PAI-1 positive staining localized in the Sertoli cells, spermatids and resi dual bodies of the seminiferous epithelium; Northern blot analysis fur ther confirmed the presence of both tPA and PAI-1 mRNA in monkey Serto li cells. Addition of follicle-stimulating hormone (FSH) or cyclic ade nosine monophosphate (cAMP) derivatives or cAMP-generating agents and gonadotrophin-releasing hormone (GnRH) agonist or phorbol ester (PMA) to the cell culture significantly increased tPA activity. PAI-1 activi ty in the culture was also enhanced by these reagents except 8-bromo-d ibutyryl-cAMP, forskolin and 3-isobutyl-1-methylxanthin (MIX) which gr eatly stimulated tPA activity, whereas decreased PAI-1 activity, imply ing that neutralization of PAI-1 activity by tile high level of tPA in the conditioned media may occur. These data suggest that increased in tracellular signals which activate protein kinase A (PKA), or protein kinase C (PKC) can modulate Sertoli cell tPA and PAI-1 activities, The concomitant induction of PA and PAI-1 by the same reagents in the Ser toli cells may reflect a finely tuned regulatory mechanism in which PA I-1 could limit the excession of the proteolysis.