Showing papers by "Pablo E. Visconti published in 2014"
TL;DR: This review unifies state of the art knowledge of the role of cAMP and those enzymes involved in cAMP signaling pathways required for the acquisition of fertilizing capacity of mammalian sperm.
153 citations
TL;DR: The presence of proline-rich tyrosine kinase 2 (PYK2), a focal adhesion kinase (FAK) family member, in human sperm, and the use of PF431396, an FAK inhibitor, supported the involvement of PYK 2 in Tyr phosphorylation downstream of PKA activation.
Abstract: Sperm capacitation involves an increase in intracellular Ca 2+ concentration as well as in protein kinase A (PKA)-dependent protein tyrosine (Tyr) phosphorylation. Interestingly, in humans, a decrease in extracellular Ca 2+ concentration ((Ca 2+ )e) during capacitation induces an increase in Tyr phosphorylation indicating the complexity of Ca 2+ signaling during this process. In view of this, in the present study we further investigated the Ca 2+ -mediated signaling pathways implicated in Tyr phosphorylation during human sperm capacitation. Results revealed that sperm incubation in a medium without added Ca 2+ (⊖ Ca 2+ ) increased Tyr phosphorylation but did not modify PKA-mediated phosphorylation. Moreover, inhibition of either PKA or Src family kinase signaling cascades in ⊖ Ca 2+ down-regulated both PKA substrate and Tyr phosphorylations, indicating that the (Ca 2+ )e effects on Tyr phosphorylation depend on PKA targets. Inhibition of calmodulin or Ser/ Thr protein phosphatase 2B also increased Tyr phosphorylation without affecting PKA-mediated phosphorylation, supporting the potential role of these Ca 2+ downstream effectors in the increase in Tyr phosphorylation observed in ⊖ Ca 2+ . Experiments aimed to identify the kinase responsible for these observations revealed the presence of proline-rich tyrosine kinase 2 (PYK2), a focal adhesion kinase (FAK) family member, in human sperm, and the use of PF431396, an FAK inhibitor, supported the involvement of PYK2 in Tyr phosphorylation downstream of PKA activation. Results also showed that PYK2 was activated in ⊖ Ca 2+ as well as during capacitation and that PF431396 affected capacitated sperm motility, acrosome reaction and ability to penetrate both mouse cumulus matrix and zona-free hamster eggs. Together, our observations support PYK2 as an intermediary component of Ca 2+ signaling between PKA-mediated and Tyr phosphorylations that is required for achieving
46 citations
TL;DR: It is demonstrated that activation of calcineurin (aka PP2B and PPP3) is required for the shift from in situ to progressive sperm motility, and no crosstalk is observed between these signaling events, even though both pathways are required for progressive motility acquisition.
Abstract: Fil: Krapf, Dario. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Rosario. Instituto de Biologia Molecular y Celular de Rosario; Argentina
17 citations
01 Jan 2014
TL;DR: The results suggest that Ca2+ ions regulate sperm cAMP and tyrosine phosphorylation pathways in a biphasic manner and that some of its effects are mediated by calmodulin.
Abstract: Mammalian sperm acquire fertilizing ability in the female tract in a process known as capacitation. At the molecular level, capacitation is associated with up‐regulation of a cAMP‐dependent pathway, changes in intracellular pH, intracellular Ca2+, and an increase in tyrosine phosphorylation. How these signaling systems interact during capacitation is not well understood. Results presented in this study indicate that Ca2+ ions have a biphasic role in the regulation of cAMP‐dependent signaling. Media without added Ca2+ salts (nominal zero Ca2+) still contain micromolar concentrations of this ion. Sperm incubated in this medium did not undergo PKA activation or the increase in tyrosine phosphorylation suggesting that these phosphorylation pathways require Ca2+. However, chelation of the extracellular Ca2+ traces by EGTA induced both cAMP‐dependent phosphorylation and the increase in tyrosine phosphorylation. The EGTA effect in nominal zero Ca2+ media was mimicked by two calmodulin antagonists, W7 and calmidazolium, and by the calcineurin inhibitor cyclosporine A. These results suggest that Ca2+ ions regulate sperm cAMP and tyrosine phosphorylation pathways in a biphasic manner and that some of its effects are mediated by calmodulin. Interestingly, contrary to wild‐type mouse sperm, sperm from CatSper1 KO mice underwent PKA activation and an increase in tyrosine phosphorylation upon incubation in nominal zero Ca2+ media. Therefore, sperm lacking Catsper Ca2+ channels behave as wild‐type sperm incubated in the presence of EGTA. This latter result suggests that Catsper transports the Ca2+ involved in the regulation of cAMP‐dependent and tyrosine phosphorylation pathways required for sperm capacitation. J. Cell. Physiol. 230: 1758–1769, 2015. © 2015 Wiley Periodicals, Inc.
6 citations