title: Focal adhesion kinase is required for actin polymerization and remodeling of the cytoskeleton during sperm capacitation.
abstract: Several focal adhesion proteins are known to cooperate with integrins to link the extracellular matrix to the actin cytoskeleton; as a result, many intracellular signaling pathways are activated and several focal adhesion complexes are formed. However, how these proteins function in mammalian spermatozoa remains unknown. We confirm the presence of focal adhesion proteins in guinea pig spermatozoa, and we explore their role during capacitation and the acrosome reaction, and their relationship with the actin cytoskeleton. Our results suggest the presence of a focal adhesion complex formed by β1-integrin, focal adhesion kinase (FAK), paxillin, vinculin, talin, and α-actinin in the acrosomal region. Inhibition of FAK during capacitation affected the protein tyrosine phosphorylation associated with capacitation that occurs within the first few minutes of capacitation, which caused the acrosome reaction to become increasingly Ca(2+) dependent and inhibited the polymerization of actin. The integration of vinculin and talin into the complex, and the activation of FAK and paxillin during capacitation, suggests that the complex assembles at this time. We identify that vinculin and α-actinin increase their interaction with F-actin while it remodels during capacitation, and that during capacitation focal adhesion complexes are structured. FAK contributes to acrosome integrity, likely by regulating the polymerization and the remodeling of the actin cytoskeleton.
authors.affiliation: Departamento de Biología Celular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, México D.F. 07360, México Posgrado en Biología Experimental, Universidad Autónoma Metropolitana-Iztapalapa, México D.F. 09349, México.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Roa-Espitia
authors.affiliation: Departamento de Biología Celular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, México D.F. 07360, México.
authors.forename: Eva R
authors.initials: ER
authors.lastname: Hernández-Rendón
authors.affiliation: Universidad Autónoma Benito Juárez de Oaxaca, Facultad de Medicina y Cirugía, Oaxaca, Oaxaca 68120, México.
authors.forename: Rafael
authors.initials: R
authors.lastname: Baltiérrez-Hoyos
authors.affiliation: Facultad de Ciencias Veterinarias, Universidad de Zulia, Maracaibo 4012, Venezuela.
authors.forename: Rafaela J
authors.initials: RJ
authors.lastname: Muñoz-Gotera
authors.affiliation: Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México 62210, Cuernavaca, México.
authors.forename: Antonieta
authors.initials: A
authors.lastname: Cote-Vélez
authors.affiliation: Posgrado en Biología Experimental, Universidad Autónoma Metropolitana-Iztapalapa, México D.F. 09349, México.
authors.forename: Irma
authors.initials: I
authors.lastname: Jiménez
authors.affiliation: Departamento de Ciencias de la Salud, Universidad Autónoma Metropolitana-Iztapalapa, México D.F. 09349, México.
authors.forename: Humberto
authors.initials: H
authors.lastname: González-Márquez
authors.affiliation: Departamento de Biología Celular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, México D.F. 07360, México eoton@cell.cinvestav.mx eoton7003@hotmail.com.mx.
authors.forename: Enrique O
authors.identifier: http://orcid.org/0000-0002-1249-981X
authors.initials: EO
authors.lastname: Hernández-González
keywords: Acrosome reaction; Calcium PyK2; Capacitation; Cytoskeleton; Protein tyrosine (Tyr) phosphorylation