title: Calcineurin role in porcine oocyte activation.
abstract: Calcineurin is required for oocyte exit from meiotic block in metaphase II (MII) stage in invertebrates and also in lower vertebrates. However, the role of calcineurin in mammalian oocyte activation is still unclear. The aim of this study was to determine whether calcineurin is involved in the processes regulating porcine oocyte activation. Indirect immunofluorescence demonstrated localization of both calcineurin subunits, CnA and CnB, especially in the cortex area of MII oocytes, in vitro fertilized and also parthenogenetically activated oocytes. After activation, the fluorescence intensity of the protein in the cortex area of oocytes remains unchanged; the protein calcineurin in the cytoplasm was recorded mainly around the pronuclei. Treatment of matured oocytes with calcineurin inhibitors, cyclosporin A (CsA) and hymenistatin I (HS-I), followed by activation with calcium ionophore A23187, significantly decreased the rate of activated oocytes compared to oocytes that were treated only with calcium ionophore (Ca-Io), (CsA+Ca-Io 25.0% v. Ca-Io 83.3%; HS-I+Ca-Io 32.5% v. Ca-Io 85.0%). Compared to the control, CsA treatment of matured oocytes followed by activation with Ca-Io did not affect the activity level of metaphase-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) in activated oocytes evaluated by kinase activity assay. Simultaneous staining of calcineurin and cortical granule content in matured oocytes showed that calcineurin distributed in the cortical area of the oocyte has not been colocalized with cortical granules content. On the other hand, the calcineurin inhibition before parthenogenetic activation leads to a reduction of the cortical reaction level compared to oocytes that were not treated with CsA (complete exocytosis: CsA+Ca-Io 2.6% v. Ca-Io 83.9%; sum of cortical granule brightness: CsA + Ca-Io 0.69 v. Ca-Io 0.15). Our results showed that calcineurin is involved in the process of pig oocyte activation and cortical granule exocytosis; however this regulation seems to be MPF and MAPK independent.
authors.affiliation: 1Department of Veterinary Sciences, Faculty of Agrobiology,Food and Natural Resources,Czech University of Life Sciences in Prague,165 21 Prague 6 - Suchdol,Czech Republic.
authors.forename: L
authors.initials: L
authors.lastname: Tůmová
authors.affiliation: 1Department of Veterinary Sciences, Faculty of Agrobiology,Food and Natural Resources,Czech University of Life Sciences in Prague,165 21 Prague 6 - Suchdol,Czech Republic.
authors.forename: E
authors.initials: E
authors.lastname: Chmelíková
authors.affiliation: 1Department of Veterinary Sciences, Faculty of Agrobiology,Food and Natural Resources,Czech University of Life Sciences in Prague,165 21 Prague 6 - Suchdol,Czech Republic.
authors.forename: T
authors.initials: T
authors.lastname: Žalmanová
authors.affiliation: 1Department of Veterinary Sciences, Faculty of Agrobiology,Food and Natural Resources,Czech University of Life Sciences in Prague,165 21 Prague 6 - Suchdol,Czech Republic.
authors.forename: V
authors.initials: V
authors.lastname: Kučerová-Chrpová
authors.affiliation: 3Department of Physiology, Faculty of Veterinary,Campus Mare Nostrum,University of Murcia,IMIB-Arrixaca,30100 Murcia,Spain.
authors.forename: R
authors.initials: R
authors.lastname: Romar
authors.affiliation: 1Department of Veterinary Sciences, Faculty of Agrobiology,Food and Natural Resources,Czech University of Life Sciences in Prague,165 21 Prague 6 - Suchdol,Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Dvořáková
authors.affiliation: 1Department of Veterinary Sciences, Faculty of Agrobiology,Food and Natural Resources,Czech University of Life Sciences in Prague,165 21 Prague 6 - Suchdol,Czech Republic.
authors.forename: K
authors.initials: K
authors.lastname: Hošková
authors.affiliation: 2Institute of Animal Science,104 00 Prague 22-Uhříněves,Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Petr
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000494:pharmacology*; D061207:Calcium Ionophores / Q000494:pharmacology; D005089:Exocytosis; D005307:Fertilization in Vitro; D059471:In Vitro Oocyte Maturation Techniques / Q000662:veterinary; D008677:Metaphase; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism; D010312:Parthenogenesis / Q000502:physiology; D013552:Swine / Q000502:physiology*
chemical_list: D061207:Calcium Ionophores; D019703:Calcineurin
keywords: activation; calcineurin; cortical granule exocytosis; oocyte; pig