Differential expression of extracellular matrix components in the bovine oviduct during the oestrous cycle

Components of the extracellular matrix take part in tissue rebuilding as we ll as activating surface-bound growth factors. In the present study, expres sion and selected activities of urokinase-type plasminogen activator (uPA), matrix metalloproteinases (MMPs), their inhibitors (plasminogen activator inhibitor 1 (PAI-1) and tissue inhibitors of metalloproteinases (TIMPs)) we re examined in bovine oviducts by RT-PCR, ribonuclease protection assay and activity assays. A high content of mRNA encoding for uPA was detected befo re ovulation with a three-fold decrease after ovulation. In contrast, PAI-1 expression appeared to be stable during the oestrous cycle. Oviductal flus hings produced caseinolytic zones in zymograms containing plasminogen at ap proximately 50 kDa and 28 kDa. An activity assay for uPA showed highest net activity during the early to mid-luteal phase. Increased TIMP-1 and MMP-2 mRNA concentrations were found around the time of ovulation compared with t he luteal phase. In contrast, MMP-1 mRNA transcripts were enriched during t he early to mid-luteal phase. Gelatin zymograms detected a 70-72 kDa protea se activity showing an oestrous cycle-dependent activity with highest activ ity before ovulation. Reverse zymography detecting TIMPs revealed proteins between 21 kDa and 24 kDa. Only for the smallest (21 kDa) protein were amou nts increased around the time of ovulation compared with the luteal phase. The observation that several extracellular matrix components were regulated distinctly in bovine oviducts indicates that focal interactions between th ese components, growth factors, gametes and the embryo are possible and may influence fertilization and early embryonic development.