CHANGES IN THE BOVINE ZONA-PELLUCIDA-INDUCED BY PLASMIN OR EMBRYONIC PLASMINOGEN-ACTIVATOR

Effects of bovine plasmin and plasminogen activator recovered from bov ine embryo-conditioned medium (bePA) on the polypeptide profile and so lubility of bovine zonae pellucidae (ZP) were evaluated. ZP were isola ted from bovine ovarian oocytes and incubated at 39 degrees C with 0, 100, or 200 mu g/ml plasmin for 0, 24, or 48 hr or bePA with 0 or 100 mu g/ml human plasminogen for 0 or 48 hr. ZP were evaluated either by SDS-PAGE or for changes in solubility using a zona pellucida dissoluti on time (ZPDT) assay. Two prominent polypeptides, molecular weight (MW ) 76,000 and 65,000, and two minor polypeptides, MW 23,000 and 22,000, were resolved by SDS-PAGE. No changes occurred in the polypeptide pro file for ZP incubated with 0 mu g/ml plasmin for 0, 24, or 48 hr, and ZPDT did not differ (P > 0.10). Treatment with 100 or 200 mu g/ml plas min induced reductions in the MW 76,000, 23,000, and 22,000 polypeptid es and the appearance of MW 45,000 and <10,000 polypeptides. ZPDT were less (P < 0.05) in 100 and 200 mu g/ml compared with 0 mu g/ml plasmi n. Polypeptide profiles and ZPDT for ZP incubated with bePA were simil ar (P > 0.10) to ZP incubated with unconditioned medium. Addition of h uman plasminogen to ZP incubated with bePA reduced the MW 76,000, 23,0 00, and 22,000 polypeptides, caused the appearance of MW 45,000 and 20 ,000 polypeptides, and decreased ZPDT (P < 0.05). These results demons trate that bovine plasmin is capable of proteolytically degrading the bovine ZP and that bePA can indirectly affect the ZP by converting pla sminogen to plasmin. (C) 1998 Wiley-Liss, Inc.