title: Localization in Oogenesis of Maternal Regulators of Embryonic Development.
abstract: Cell polarity generates intracellular asymmetries and functional regionalization in tissues and morphogenetic processes. Cell polarity in development often relies on mechanisms of RNA localization to specific subcellular domains to define the identity of future developing tissues. The totipotent egg of most animals illustrates in a grand way the importance of cell polarity and RNA localization in regulating multiple crucial developmental events. The polarization of the egg arises during its development in oogenesis. RNAs localize asymmetrically in the early oocyte defining its animal-vegetal (AV) axis, which upon further elaboration in mid- and late-oogenesis stages produces a mature egg with specific localized factors along its AV axis. These localized factors will define the future anterior-posterior (AP) and dorsal-ventral (DV) axes of the embryo. Furthermore, AV polarity confines germ cell determinants to the vegetal pole, from where they redistribute to the cleavage furrows of the 2- and 4-cell stage embryo, ultimately specifying the primordial germ cells (PGCs). The sperm entry region during fertilization is also defined by the AV axis. In frogs and fish, sperm enters through the animal pole, similar to the mouse where it enters predominantly in the animal half. Thus, AV polarity establishment and RNA localization are involved in all the major events of early embryonic development. In this chapter, we will review the RNA localization mechanisms in vertebrate oocytes that are key to embryonic patterning, referring to some of the groundbreaking studies in frog oocytes and incorporating the current genetic evidence from the zebrafish.
authors.affiliation: Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, 1152 BRBII/III, 421 Curie Boulevard, Philadelphia, PA, 19104-6058, USA.
authors.forename: Matias
authors.initials: M
authors.lastname: Escobar-Aguirre
authors.affiliation: Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, 1152 BRBII/III, 421 Curie Boulevard, Philadelphia, PA, 19104-6058, USA.
authors.forename: Yaniv M
authors.initials: YM
authors.lastname: Elkouby
authors.affiliation: Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, 1152 BRBII/III, 421 Curie Boulevard, Philadelphia, PA, 19104-6058, USA. mullins@mail.med.upenn.edu.
authors.forename: Mary C
authors.initials: MC
authors.lastname: Mullins
mesh_terms: D000818:Animals; D016764:Cell Polarity / Q000235:genetics*; D047108:Embryonic Development / Q000235:genetics*; D005306:Fertilization / Q000235:genetics; D005854:Germ Cells / Q000254:growth & development / Q000378:metabolism; D051379:Mice; D009024:Morphogenesis / Q000235:genetics; D009865:Oocytes / Q000254:growth & development; D009866:Oogenesis / Q000235:genetics*; D012313:RNA / Q000235:genetics*; D014981:Xenopus / Q000196:embryology; D015027:Zebrafish / Q000196:embryology
chemical_list: D012313:RNA
keywords: Animal-vegetal axis; Axis formation; Balbiani body; Bucky ball; Cytoskeleton; Fertilization; Germplasm; Oocyte polarity; Oogenesis; RNA localization