Browsing by Subject "Plasmin"

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    How is plasminogen/plasmin system contributing to regulate sperm entry into the oocyte?
    (2013-12-30) Grullón LA; Gadea Mateos, Joaquín; Mondéjar Corbalán, Irene; Romar Andrés, Raquel; Matas Parra, Carmen; Coy Fuster, Pilar; Coy Fuster, Pilar; Fisiología; Facultades de la UMU
    Plasminogen is present in the oviduct, on the zona pellucida (ZP) and on oolemma, and reduces the number of sperm penetrating the oocyte during in vitro fertilization in pig and cow. It is unknown how this reduction occurs. We tested whether plasminogen (1) changed the ZP resistance to enzymatic digestion thus making the passage of the spermatozoa across it difficult; (2) reduced the sperm functionality, assessed by sperm viability, motility, spontaneous acrosome reaction and membrane lipid disorder; or (3) affected the sperm-ZP binding before or after sperm-ZP interaction. The mechanism by which plasminogen/plasmin system contributes to regulate sperm entry into the oocyte is not inducing a ZP hardening or a decrease in sperm functionality but detaching more than 50% of sperm bound to the ZP. It is suggested that the fertilizing spermatozoon activates plasminogen into plasmin at the oocyte surface and that plasmin removes additional spermatozoa attached to the ZP.
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    Oocytes use the plasminogen-plasmin system to remove supernumerary spermatozoa
    (2012-05-03) Grullón LA; Coy Fuster, Pilar; Jíménez Movilla, María; García Vázquez, Francisco Alberto; Mondéjar Corbalán, Irene; Romar Andrés, Raquel; Romar Andrés, Raquel; Fisiología
    background: The role of the plasminogen-plasmin (PLG-PLA) system in fertilization is unknown, although its dysfunction has been associated with subfertility in humans. We have recently detected and quantified plasminogen in the oviductal fluid of two mammals and showed a reduction in sperm penetration during IVF when plasminogen is present. The objective of this study was to describe the mechanism by which PLG-PLA system regulates sperm entry into the oocyte. methods and results: By combining biochemical, functional, electron microscopic, immunocytochemical and live cell imaging methods, we show here that (i) plasminogen is activated into the protease plasmin, by gamete interaction; (ii) urokinase-type and tissuetype plasminogen activators are present in oocytes, but they are not of cortical granule origin; (iii) sperm binding to oocytes triggers the releasing of plasminogen activators and (iv) the generated plasmin causes sperm detachment from the zona pellucida. conclusions: Our results describe a novel mechanism for the success or failure of fertilization in mammals, by which molecules present in the oviductal environment are activated by molecules originating within the gametes. We anticipate that therapeutic up- or down-regulation of this physiological mechanism may be used to help in conception or as a contraceptive tool. Since components of the PLG-PLA system are already available as drugs for heart attacks or cancer therapies, basic research on this novel function would be rapidly transferable for clinical application.
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    Post translational activation of latent transforming growth factor beta (L-TGF-O): clinical implications
    (Murcia : F. Hernández, 2001) Khalil, N.
    Transforming growth factor-betas (TGF-Bs) are multifunctional cytokines that exist in 3 isoforms in mammals. The TGF-Bs are ubiquitously expressed and al1 isoforms are secreted as biologically inactive precursors called latent TGF-B (L-TGF- B). LTGF-Bs are generally not effective molecules because they are unable to interact with their receptors. However, the removal of or conformational change of the precursor protein called the latency associated peptide (LAP) results in the generation of biologically active TGF- B. Zn vitro active TGF-B has many biological effects but from a clinical point of view one of the most recognized associations of aberrant TGF-B production is with diseases characterized by enhanced connective tissue synthesis. Recently a number of observations in the context of fibrotic disorders suggest mechanisms of activation of L-TGF-61 in vivo. The recognition of mechanisms that activate L-TGF-81 in vivo offers the possibiiity of interfering with the activation of L-TGFB1 for therapeutic purposes.