Mammalian sperm are not able to fertilize eggs immediately after ejaculation. They acquire fertilization capacity after residing in the female tract for a finite period of time in a process known as capacitation [24, 25]. Initially, capacitation was defined using fertilization as end-point. However, a variety of evidences suggest that the functional changes occurring in the sperm during capacitation are not one event, but a combination of sequential and concomitant processes. Some of these processes occur as soon as the sperm are released from the epididymis, others are slower and are activated only after sperm incubation for a certain period of time in conditions that support the sperm ability to fertilize the egg. These slow events are associated with changes in the motility pattern (e.g. hyperactivation) and with the acquisition of the sperm capacity to undergo an agonist-stimulated acrosome reaction (AR). Although both, fast and slow events are regulated by HCO3- and by a cAMP-dependent pathway, slower events are limited by the release of cholesterol from the sperm plasma membrane. Using the mouse as an experimental model, we have demonstrated that these last events are associated with a protein kinase A (PKA)-dependent increase in the tyrosine (tyr) phosphorylation of a subset of proteins [23, 26]. Simultaneously with our findings, Zeng et al. (1995) reported that capacitation is accompanied by hyperpolarization of the sperm plasma membrane ootential (Em). It has been hypothesized that hyperpolarization is necessary to drive Low Voltage Activated (LVA) Ca2+ T-channels (Cav3) from an inactive state to a closed state that can be activated by agonists such as the zona pellucida (ZP), triggering the AR. Despite these advances, little is known on how these molecular changes are combined to promote capacitation. As part of the first cycle of this grant, we have shown that HCO3-, Na+ and K+ are involved in the regulation of the sperm Em [21, 27, 28] and that Epithelial Na+ channels (ENaC) are present in sperm and play an important role in the regulation of the sperm resting Em [21]. The objective of this proposal is to understand how changes in cAMP, protein phosphorylation and hyperpolarization integrate to promote capacitation. Investigation of the crosstalk between cAMP and the changes in ion permeability is essential to understand the molecular basis of capacitation and to provide novel targets for pharmacological control of the fertilization process.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD038082-11
Application #
8121607
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Moss, Stuart B
Project Start
2000-07-01
Project End
2013-08-31
Budget Start
2011-09-01
Budget End
2013-08-31
Support Year
11
Fiscal Year
2011
Total Cost
$271,690
Indirect Cost
Name
University of Massachusetts Amherst
Department
Veterinary Sciences
Type
Schools of Earth Sciences/Natur
DUNS #
153926712
City
Amherst
State
MA
Country
United States
Zip Code
01003
Puga Molina, Lis C; Pinto, Nicolás A; Torres Rodríguez, Paulina et al. (2017) Essential Role of CFTR in PKA-Dependent Phosphorylation, Alkalinization, and Hyperpolarization During Human Sperm Capacitation. J Cell Physiol 232:1404-1414
Gervasi, M G; Visconti, P E (2017) Molecular changes and signaling events occurring in spermatozoa during epididymal maturation. Andrology 5:204-218
Stival, Cintia; Puga Molina, Lis del C; Paudel, Bidur et al. (2016) Sperm Capacitation and Acrosome Reaction in Mammalian Sperm. Adv Anat Embryol Cell Biol 220:93-106
Romarowski, Ana; Sánchez-Cárdenas, Claudia; Ramírez-Gómez, Héctor V et al. (2016) A Specific Transitory Increase in Intracellular Calcium Induced by Progesterone Promotes Acrosomal Exocytosis in Mouse Sperm. Biol Reprod 94:63
Alvau, Antonio; Battistone, Maria Agustina; Gervasi, Maria Gracia et al. (2016) The tyrosine kinase FER is responsible for the capacitation-associated increase in tyrosine phosphorylation in murine sperm. Development 143:2325-33
Navarrete, Felipe A; Alvau, Antonio; Lee, Hoi Chang et al. (2016) Transient exposure to calcium ionophore enables in vitro fertilization in sterile mouse models. Sci Rep 6:33589
Ramos-Espiritu, Lavoisier; Kleinboelting, Silke; Navarrete, Felipe A et al. (2016) Discovery of LRE1 as a specific and allosteric inhibitor of soluble adenylyl cyclase. Nat Chem Biol 12:838-44
Beltrán, Carmen; Treviño, Claudia L; Mata-Martínez, Esperanza et al. (2016) Role of Ion Channels in the Sperm Acrosome Reaction. Adv Anat Embryol Cell Biol 220:35-69
Navarrete, Felipe A; García-Vázquez, Francisco A; Alvau, Antonio et al. (2015) Biphasic role of calcium in mouse sperm capacitation signaling pathways. J Cell Physiol 230:1758-1769
Sánchez-Carranza, Oscar; Torres-Rodríguez, Paulina; Darszon, Alberto et al. (2015) Pharmacology of hSlo3 channels and their contribution in the capacitation-associated hyperpolarization of human sperm. Biochem Biophys Res Commun 466:554-9

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