Plasminogen Detection in Oocytes and Plasminogen Activators Activities in the Porcine Oviduct During the Estrous Cycle

ROLDÁN OLARTE, MARIELA; JIMÉNEZ-DÍAZ, MARÍA AND MICELI, DORA C.

ZYGOTE

Cambridge University Press

Lugar: Cambridge; Año: 2005 vol. 13 p. 115 - 123

0967-1994

Plasminogen activators (PAs) are highly specific serine proteases that convert the extracellular zymogen plasminogen into the active proteinase plasmin. Plasminogen dependent proteolytic activity was detected by zymography both in the tissue membrane fraction of oviducts and in the oviductal flushing obtained at the preovulatory (Pre-Ov), postovulatory (Post-Ov) and mid-luteal (Mid-L) stages of the estrous cycle. A main proteolytic band, with a relative mobility similar to a human melanoma cells tissue type plasminogen activator (t-PA), was found in all samples. Two additional components were observed in Pre-Ov and Post-Ov oviductal flushing but no in tissue membrane fraction. In the oviductal flushing the PAs activity was significantly higher in the Post-Ov stage than in the Pre-Ov one. Both urokinase type plasminogen activator (u-PA, 50 kDa) and t-PA (72 kDa) were detected by Western blot; they showed differences in their relative concentration between Post-Ov and Pre-Ov oviductal flushing. The main PAs substrate, plasminogen, was detected by indirect immunofluorescence in the cumulus cells extracellular matrix (ECM) and oocytes zona pellucida (ZP). In denuded oocytes, plasminogen was also detected on the surface of the plasma membrane. It is possible that oviductal PAs may act on the plasminogen present in the cumulus cells ECM and ZP; consequently, the generated plasmin could be involved in the rebuilding or degradation of these oocyte structures during fertilization or early development.