Cellular Regulation of Plasminogen Activator Secretion During Spermatogenesis

Abstract

The secretion of plasminogen activator (PA) has been found to be highly stage-specific during rat spermatogenesis. It is maximal in Stages VII and VIII of the cycle. At these stages, seminiferous tubules contain primitive type A1 spermatogonia, preleptotene and midpachytene primary spermatocytes, round and maturation-phase spermatids and Sertoli cells. The last cell types are the most likely sources of PA. To investigate which cell type might be involved in the regulation of PA secretion, we have sequentially isolated 1-mm segments of rat seminiferous tubules from Stages VI-IX with transillumination-assisted microdissection and measured PA secretion using 125I-labeled fibrinogen as substrate. In another experiment, spermatogenia were killed by 300 rads of x-rays and PA secretion was analyzed during the absence of desired germ cell classes. The results support the idea that upon their detachment from the basal lamina, preleptotene-stage primary spermatocytes have the major stimulatory action on the PA secretion of the seminiferous tubules. Other phenomena such as spermiation, phagocytosis of residual bodies or opening up of the Sertoli cell junctions seem to influence PA secretion to a lesser extent.

Effect of an acute exposure of rat testes to gamma rays on germ cells and on Sertoli and Leydig cell functions

“…Spermatogonia are known to be the most radiosensitive cells in the testis, but if the radiation dose is higher, more differentiated cells can also be destroyed (Shaver, 1953;Oakberg and Di Minno, 1960 Huckins, 1978;Hopkinson et al, 1978;Main et al, 1978;Wang et al, 1983;Pinon-Lataillade et al, 1985;Delic et al, 1986;Kamtchouing et al, 1988;Pineau et al, 1989 (Parvinen, 1982; Sharpe, 1986;J6gou et al, 1988;Verhoeven and Cailleau, 1989 (J6gou et al, 1988). One possible approach to the investigation of this complex aspect of the paracrine regulation of spermatogenesis has been to use different protocols of irradiation which, in vivo, were found to induce different degrees of seminiferous epithelium modification (Rich and De Kretser, 1977;Hopkinson et al, 1978;Vihko et al, 1984;PinonLataillade et al, 1985PinonLataillade et al, , 1988Pineau et al, 1989;Kangasniemi et al, 1990a, b). De (Setchell et al, 1977;Weinbauer et al, 1989) The detection limits were 100 ng/ml for FSH and 0.6 ng/mi for LH, and the intra-assay coefficient of variation was 10% for both.…”

Local synthesis of plasminogen by the seminiferous tubules of the testis

“…Urokinase-like plasminogen activator can be immunochemically localized in Sertoli cells, where it is seen in Golgi-like structures of the cytoplasm [22]. The secretion of this proteinase from the separated seminiferous structures is cyclic and is most prominent from the stages VII-VIII [7][8][9]221. The secretion of plasminogen activator is at least partially regulated by the preleptotene primary spermatocytes [7].…”

“…The secretion of this proteinase from the separated seminiferous structures is cyclic and is most prominent from the stages VII-VIII [7][8][9]221. The secretion of plasminogen activator is at least partially regulated by the preleptotene primary spermatocytes [7]. In addition, Sertoli cells increase their plasminogen activator secretion after stimulation with the follicle stimulating hormone and cyclic AMP [8].…”

“…In addition, Sertoli cells increase their plasminogen activator secretion after stimulation with the follicle stimulating hormone and cyclic AMP [8]. Potential targets for the action of plasminogen activation-mediated proteolysis are the matrix components during detachment of the primary spermatocytes from the basement membrane or dissolution of the intercellular junctions between the Sertoli cells, which occurs during the transport and maturation of the spermatocytes into the lumen of the tubules [7]. A role for the proteolytic activity in the modulation of cell-secreted proteins could also be anticipated [23,24].…”

Age-dependent changes in the in-vitro response of a pig Sertoli cell-enriched population to FSH

“…As in rat testis homogenates, PA levels increased at 9 days of age, concomitantly with the appearance of preleptotene spermatocytes . Other approaches using isolated seminiferous tubule segments at different stages of the cycle of the seminiferous epithelium led to the conclusion that preleptotene spermato¬ cytes upon their release from the basal lamina at the onset of meiosis are important regulators of PA secretion (Vihko et al, 1984).…”