title: PKA-dependent phosphorylation of LIMK1 and Cofilin is essential for mouse sperm acrosomal exocytosis.
abstract: Mammalian sperm must acquire their fertilizing ability after a series of biochemical modifications in the female reproductive tract collectively called capacitation to undergo acrosomal exocytosis, a process that is essential for fertilization. Actin dynamics play a central role in controlling the process of exocytosis in somatic cells as well as in sperm from several mammalian species. In somatic cells, small GTPases of the Rho family are widely known as master regulators of actin dynamics. However, the role of these proteins in sperm has not been studied in detail. In the present work we characterized the participation of small GTPases of the Rho family in the signaling pathway that leads to actin polymerization during mouse sperm capacitation. We observed that most of the proteins of this signaling cascade and their effector proteins are expressed in mouse sperm. The activation of the signaling pathways of cAMP/PKA, RhoA/C and Rac1 is essential for LIMK1 activation by phosphorylation on Threonine 508. Serine 3 of Cofilin is phosphorylated by LIMK1 during capacitation in a transiently manner. Inhibition of LIMK1 by specific inhibitors (BMS-3) resulted in lower levels of actin polymerization during capacitation and a dramatic decrease in the percentage of sperm that undergo acrosomal exocytosis. Thus, we demonstrated for the first time that the master regulators of actin dynamics in somatic cells are present and active in mouse sperm. Combining the results of our present study with other results from the literature, we have proposed a working model regarding how LIMK1 and Cofilin control acrosomal exocytosis in mouse sperm.
authors.affiliation: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
authors.forename: Ana
authors.initials: A
authors.lastname: Romarowski
authors.affiliation: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
authors.forename: María A
authors.initials: MA
authors.lastname: Battistone
authors.affiliation: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
authors.forename: Florenza A
authors.initials: FA
authors.lastname: La Spina
authors.affiliation: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
authors.forename: Lis del C
authors.initials: Ldel C
authors.lastname: Puga Molina
authors.affiliation: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
authors.forename: Guillermina M
authors.initials: GM
authors.lastname: Luque
authors.affiliation: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
authors.forename: Alejandra M
authors.initials: AM
authors.lastname: Vitale
authors.affiliation: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Cuasnicu
authors.affiliation: Department of Veterinary and Animal Science, Paige Labs, University of Massachusets, Amherst, MA 01003, USA.
authors.forename: Pablo E
authors.initials: PE
authors.lastname: Visconti
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR), Rosario 2000 Argentina.
authors.forename: Darío
authors.initials: D
authors.lastname: Krapf
authors.affiliation: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina. Electronic address: mgbuffone@ibyme.conicet.gov.ar.
authors.forename: Mariano G
authors.initials: MG
authors.lastname: Buffone
mesh_terms: D020101:Acrosome Reaction / Q000502:physiology*; D000199:Actins / Q000378:metabolism; D000818:Animals; D051338:Cofilin 1 / Q000378:metabolism*; D003433:Crosses, Genetic; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D005089:Exocytosis; D005786:Gene Expression Regulation; D054461:Lim Kinases / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D015398:Signal Transduction; D013075:Sperm Capacitation / Q000502:physiology*; D013094:Spermatozoa / Q000378:metabolism
chemical_list: D000199:Actins; C495811:Cfl1 protein, mouse; D051338:Cofilin 1; D054461:Lim Kinases; C515893:Limk1 protein, mouse; D017868:Cyclic AMP-Dependent Protein Kinases
keywords: Acrosomal exocytosis; Actin; Cofilin; LIMK1; Small GTPases; Sperm