(FBIOyF) Laboratorio de Medicina Reproductiva (LMR)

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https://rephip.unr.edu.ar/handle/2133/9238

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Examinando (FBIOyF) Laboratorio de Medicina Reproductiva (LMR) por Autor "Buffone, Mariano Gabriel"

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  • Miniatura
    ÍtemAcceso Abierto
    Membrane potential assessment by fluorimetry as a predictor tool of human sperm fertilizing capacity
    (Frontiers Media, 2020-01-17) Baró Graf, Carolina; Ritagliati, Carla; Torres Monserrat, Valentina; Stival, Cintia Estefanía; Carizza, Carlos; Buffone, Mariano Gabriel; Krapf, Darío
    Mammalian sperm acquire the ability to fertilize eggs by undergoing a process known as capacitation. Capacitation is triggered as the sperm travels through the female reproductive tract. This process involves specific physiological changes such as rearrangement of the cell plasma membrane, post-translational modifications of certain proteins, and changes in the cellular permeability to ions – with the subsequent impact on the plasma membrane potential (Em). Capacitation-associated Em hyperpolarization has been well studied in mouse sperm, and shown to be both necessary and sufficient to promote the acrosome reaction (AR) and fertilize the egg. However, the relevance of the sperm Em upon capacitation on human fertility has not been thoroughly characterized. Here, we performed an extensive study of the Em change during capacitation in human sperm samples using a potentiometric dye in a fluorimetric assay. Normospermic donors showed significant Em hyperpolarization after capacitation. Em values from capacitated samples correlated significantly with the sperm ability to undergo induced AR, highlighting the role of hyperpolarization in acrosomal responsiveness, and with successful in vitro fertilization (IVF) rates. These results show that Em hyperpolarization could be an indicator of human sperm fertilizing capacity, setting the basis for the use of Em values as a robust predictor of the success rate of IVF.
  • Miniatura
    ÍtemAcceso Abierto
    The sodium–proton exchangers sNHE and NHE1 control plasma membrane hyperpolarization in mouse sperm
    (Elsevier, 2024-10-24) Novero, Analia G.; Torres Rodríguez, Paulina; De la Vega Beltrán, José L.; Schiavi Ehrenhaus, Liza J.; Luque, Guillermina M.; Carruba, Micaela; Stival, Cintia Estefanía; Gentile, Iñaki; Ritagliati, Carla; Santi, Celia M.; Nishigaki, Takuya; Krapf, Diego; Buffone, Mariano Gabriel; Darszon, Alberto; Treviño, Claudia L.; Krapf, Darío; https://orcid.org/0009-0004-7481-2121; https://orcid.org/0000-0002-2745-8236; https://orcid.org/0000-0002-2833-5553; https://orcid.org/0000-0002-7281-0534; https://orcid.org/0000-0001-7607-1954
    Sperm capacitation is a complex process that takes place in the female reproductive tract and empowers mammalian sperm with the competence to fertilize an egg. It consists of an intricate cascade of events that can be mimicked in vitro through incubation in a medium containing essential components, such as bicarbonate, albumin, Ca2+, and energy substrates, among others. Genetic and pharmacological studies have underscored the unique significance of the K+ channel SLO3 in membrane potential hyperpolarization, as evidenced by the infertility of mice lacking its expression. Notably, two key molecular events, sperm hyperpolarization and intracellular alkalinization, are central to the capacitation process. SLO3 is activated by alkalinization. However, the molecular mechanisms responsible for intracellular alkalization and activation of SLO3 are not completely understood. In this study, we examined the impact of Na+/H+ exchangers (NHEs) on mouse sperm membrane hyperpolarization during capacitation. Pharmacological inhibition of the NHE1 blocked membrane hyperpolarization. A similar effect was observed in sperm deficient of the Ca2+ channel CatSper because of NHE1 not being activated by Ca2+. In addition, the sperm-specific NHE (sNHE) KO did not show membrane hyperpolarization upon capacitation or induction with cAMP analogs. Our results show that sNHE is dually modulated by cAMP and membrane hyperpolarization probably through its cyclic nucleotide–binding domain and the voltage-sensor motif, respectively. Together, sNHE and NHE1 provide the alkalinization need for SLO3 activation during capacitation.