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García Vázquez, Francisco Alberto

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García Vázquez, Francisco Alberto
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Universidad de Murcia. Departamento de Fisiología
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    Fertilization outcome could be regulated by binding of oviductal plasminogen to oocytes and by releasing of plasminogen activators during interplay between gametes
    (2012-02-02) Grullón, LA; Mondéjar Corbalán, Irene; García Vázquez, Francisco Alberto; Romar Andrés, Raquel; Coy Fuster, Pilar; Coy Fuster, Pilar; Fisiología; Facultades de la UMU
    Objective: To detect plasminogen and plasminogen activators (PA) in oviduct and oocytes and to clarify the role of the plasminogen/plasmin system on mammalian fertilization. Design: Experimental prospective study. Setting: Mammalian reproduction research laboratory. Animal(s): Oviducts and ovaries from porcine and bovine females were collected at slaughterhouse. A total of 52 oviducts and 2,292 oocytes were used. Boar and bull ejaculated spermatozoa were also used. Intervention(s): Plasminogen concentration in oviductal fluid (OF) through the cycle was measured. Immunolocalization of plasminogen and PAs in oocytes was carried out before and after fertilization. Porcine and bovine oocytes were in vitro fertilized, with plasminogen and plasmin added to the culture medium at different concentrations. Main Outcome Measure(s): Plasminogen concentration in OF. Plasminogen and PAs immunolocalization in oocytes. Penetration and monospermy rates, number of spermatozoa in the ooplasma and on the zona pellucida (ZP) after IVF. Result(s): Oviductal fluid contains about 92 mg/mL of plasminogen. The mature oocyte shows immunoreactivity toward plasminogen and toward PAs on its oolemma and ZP. After fertilization, plasminogen and PAs immunolabeling decreases in the oocyte, suggesting its conversion into plasmin. When exogenous plasminogen is added to the IVF medium, sperm entry into the oocyte is hampered, suggesting that the role of plasminogen activation during fertilization is to reduce the number of (or to select) penetrating spermatozoa. Conclusion(s): The plasminogen/plasmin system is activated during gamete interaction and regulates the sperm entry into the oocyte
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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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    Manipulation of bicarbonate concentration in sperm capacitation media improves in vitro fertilisation output in porcine species
    (BioMed Central, 2019-03-11) Soriano-Úbeda, Cristina; Romero Aguirregomezcorta, Jon; Matas Parra, Carmen; Visconti, Pablo E.; García Vázquez, Francisco Alberto; Anatomía y Anatomía Patológica Comparada; Facultad de Veterinaria
    Background. The in vivo concentration of bicarbonate (HCO3−), one of the essential sperm capacitating effectors, varies greatly in the different environments sperm go through from cauda epididymis to the fertilisation site. On the contrary, porcine in vitro sperm capacitation and fertilisation media usually contains a standard concentration of 25 mmol/L, and one of the main problems presented is the unacceptable high incidence of polyspermy. This work hypothesised that by modifying the HCO3− concentration of the medium, the output of in vitro sperm capacitation and fertilisation could be increased. Results: Once exposed to the capacitation medium, the intracellular pH (pHi) of spermatozoa increased immediately even at low concentrations of HCO3−, but only extracellular concentrations of and above 15 mmol/L increased the substrates protein kinase A phosphorylation (pPKAs). Although with a significant delay, 15 mmol/L of HCO3− stimulated sperm linear motility and increased other late events in capacitation such as tyrosine phosphorylation (Tyr-P) to levels similar to those obtained with 25 mmol/L. This information allowed the establishment of a new in vitro fertilisation (IVF) system based on the optimization of HCO3− concentration to 15 mmol/L, which led to a 25.3% increment of the viable zygotes (8.6% in the standard system vs. 33.9%). Conclusions: Optimising HCO3− concentrations allows for establishing an IVF method that significantly reduced porcine polyspermy and increased the production of viable zygotes. A concentration of 15 mmol/L of HCO3− in the medium is sufficient to trigger the in vitro sperm capacitation and increase the fertilisation efficiency in porcine.
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