title: Biphasic role of calcium in mouse sperm capacitation signaling pathways.
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 Ca(2+), and an increase in tyrosine phosphorylation. How these signaling systems interact during capacitation is not well understood. Results presented in this study indicate that Ca(2+) ions have a biphasic role in the regulation of cAMP-dependent signaling. Media without added Ca(2+) salts (nominal zero Ca(2+)) 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 Ca(2+). However, chelation of the extracellular Ca(2+) traces by EGTA induced both cAMP-dependent phosphorylation and the increase in tyrosine phosphorylation. The EGTA effect in nominal zero Ca(2+) media was mimicked by two calmodulin antagonists, W7 and calmidazolium, and by the calcineurin inhibitor cyclosporine A. These results suggest that Ca(2+) 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 Ca(2+) media. Therefore, sperm lacking Catsper Ca(2+) channels behave as wild-type sperm incubated in the presence of EGTA. This latter result suggests that Catsper transports the Ca(2+) involved in the regulation of cAMP-dependent and tyrosine phosphorylation pathways required for sperm capacitation.
authors.affiliation: Department of Veterinary and Animal Science, Integrated Sciences Building, University of Massachusetts, Amherst MA, USA.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Navarrete
authors.affiliation: Department of Veterinary and Animal Science, Integrated Sciences Building, University of Massachusetts, Amherst MA, USA.|Department of Physiology, Veterinary School, University of Murcia, Murcia, Spain.|International Excellence Campus for Higher Education and Research (Campus Mare Nostrum) and Institute for Biomedical Research of Murcia, Murcia, Spain.
authors.forename: Francisco A
authors.initials: FA
authors.lastname: García-Vázquez
authors.affiliation: Department of Veterinary and Animal Science, Integrated Sciences Building, University of Massachusetts, Amherst MA, USA.
authors.forename: Antonio
authors.initials: A
authors.lastname: Alvau
authors.affiliation: Department of Veterinary and Animal Science, Integrated Sciences Building, University of Massachusetts, Amherst MA, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Escoffier
authors.affiliation: Instituto de Biología Celular y Molecular de Rosario (CONICET), UNR, Buenos Aires, Argentina.
authors.forename: Dario
authors.initials: D
authors.lastname: Krapf
authors.affiliation: Departamento de Genética del Desarrollo y Fisiología Molecular, IBT-UNAM, Cuernavaca, México.
authors.forename: Claudia
authors.initials: C
authors.lastname: Sánchez-Cárdenas
authors.affiliation: Department of Veterinary and Animal Science, Integrated Sciences Building, University of Massachusetts, Amherst MA, USA.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Salicioni
authors.affiliation: Departamento de Genética del Desarrollo y Fisiología Molecular, IBT-UNAM, Cuernavaca, México.
authors.forename: Alberto
authors.initials: A
authors.lastname: Darszon
authors.affiliation: Department of Veterinary and Animal Science, Integrated Sciences Building, University of Massachusetts, Amherst MA, USA.
authors.forename: Pablo E
authors.initials: PE
authors.lastname: Visconti
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D015398:Signal Transduction / Q000502:physiology*; D013075:Sperm Capacitation / Q000502:physiology*; D013081:Sperm Motility / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism
chemical_list: D015220:Calcium Channels; C488642:Catsper1 protein, mouse; D014443:Tyrosine; D000242:Cyclic AMP; D002118:Calcium