title: Relocalization of STIM1 in mouse oocytes at fertilization: early involvement of store-operated calcium entry.
abstract: Calcium waves represent one of the most important intracellular signaling events in oocytes at fertilization required for the exit from metaphase arrest and the resumption of the cell cycle. The molecular mechanism ruling this signaling has been described in terms of the contribution of intracellular calcium stores to calcium spikes. In this work, we considered the possible contribution of store-operated calcium entry (SOCE) to this signaling, by studying the localization of the protein STIM1 in oocytes. STIM1 has been suggested to play a key role in the recruitment and activation of plasma membrane calcium channels, and we show here that mature mouse oocytes express this protein distributed in discrete clusters throughout their periphery in resting cells, colocalizing with the endoplasmic reticulum marker calreticulin. However, immunolocalization of the endogenous STIM1 showed considerable redistribution over larger areas or patches covering the entire periphery of the oocyte during Ca(2+) store depletion induced with thapsigargin or ionomycin. Furthermore, pharmacological activation of endogenous phospholipase C induced a similar pattern of redistribution of STIM1 in the oocyte. Finally, fertilization of mouse oocytes revealed a significant and rapid relocalization of STIM1, similar to that found after pharmacological Ca(2+) store depletion. This particular relocalization supports a role for STIM1 and SOCE in the calcium signaling during early stages of fertilization.
authors.affiliation: Departamento de Biología Celular, Reproductive and Developmental Biology Group (ReDes), Universidad de Extremadura, Badajoz, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Gómez-Fernández
authors.forename: Eulalia
authors.initials: E
authors.lastname: Pozo-Guisado
authors.forename: Miguel
authors.initials: M
authors.lastname: Gañán-Parra
authors.forename: Mario J
authors.initials: MJ
authors.lastname: Perianes
authors.forename: Ignacio S
authors.initials: IS
authors.lastname: Alvarez
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Martín-Romero
mesh_terms: D000818:Animals; D001692:Biological Transport; D015415:Biomarkers / Q000032:analysis; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D037282:Calreticulin / Q000032:analysis; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro; D005455:Fluorescent Antibody Technique; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis*; D051379:Mice; D008815:Mice, Inbred Strains; D009865:Oocytes / Q000378:metabolism*; D000071737:Stromal Interaction Molecule 1; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D015415:Biomarkers; D015220:Calcium Channels; D037282:Calreticulin; D007476:Ionophores; D008562:Membrane Glycoproteins; C100757:Stim1 protein, mouse; D000071737:Stromal Interaction Molecule 1; D015759:Ionomycin; D019284:Thapsigargin; D010738:Type C Phospholipases; D000252:Calcium-Transporting ATPases; D002118:Calcium