title: Conserved functions for Mos in eumetazoan oocyte maturation revealed by studies in a cnidarian.
abstract: The kinase Mos, which activates intracellularly the MAP kinase pathway, is a key regulator of animal oocyte meiotic maturation. In vertebrate and echinoderm models, Mos RNA translation upon oocyte hormonal stimulation mediates "cytostatic" arrest of the egg after meiosis, as well as diverse earlier events [1-5]. Our phylogenetic survey has revealed that MOS genes are conserved in cnidarians and ctenophores, but not found outside the metazoa or in sponges. We demonstrated MAP kinase-mediated cytostatic activity for Mos orthologs from Pleurobrachia (ctenophore) and Clytia (cnidarian) by RNA injection into Xenopus blastomeres. Analyses of endogenous Mos in Clytia with morpholino antisense oligonucleotides and pharmacological inhibition demonstrated that Mos/MAP kinase function in postmeiotic arrest is conserved. They also revealed additional roles in spindle formation and positioning, strongly reminiscent of observations in starfish, mouse, and Xenopus. Unusually, cnidarians were found to possess multiple Mos paralogs. In Clytia, one of two maternally expressed paralogs accounted for the majority MAP kinase activation during maturation, whereas the other may be subject to differential translational regulation and have additional roles. Our findings indicate that Mos appeared early during animal evolution as an oocyte-expressed kinase and functioned ancestrally in regulating core specializations of female meiosis.
authors.affiliation: Université Pierre et Marie Curie, Centre National de la Recherche, Villefranche-sur-mer, France.
authors.forename: Aldine
authors.initials: A
authors.lastname: Amiel
authors.forename: Lucas
authors.initials: L
authors.lastname: Leclère
authors.forename: Lucie
authors.initials: L
authors.lastname: Robert
authors.forename: Sandra
authors.initials: S
authors.lastname: Chevalier
authors.forename: Evelyn
authors.initials: E
authors.lastname: Houliston
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003063:Cnidaria / Q000166:cytology / Q000201:enzymology*; D037302:Ctenophora / Q000166:cytology / Q000201:enzymology*; D005260:Female; D007527:Isoenzymes / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008540:Meiosis / Q000502:physiology; D051379:Mice; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology / Q000201:enzymology*; D010802:Phylogeny; D017231:Proto-Oncogene Proteins c-mos / Q000145:classification / Q000235:genetics / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D017231:Proto-Oncogene Proteins c-mos