title: Polarity and cell division orientation in the cleavage embryo: from worm to human.
abstract: Cleavage is a period after fertilization, when a 1-cell embryo starts developing into a multicellular organism. Due to a series of mitotic divisions, the large volume of a fertilized egg is divided into numerous smaller, nucleated cells-blastomeres. Embryos of different phyla divide according to different patterns, but molecular mechanism of these early divisions remains surprisingly conserved. In the present paper, we describe how polarity cues, cytoskeleton and cell-to-cell communication interact with each other to regulate orientation of the early embryonic division planes in model animals such as Caenorhabditis elegans, Drosophila and mouse. We focus particularly on the Par pathway and the actin-driven cytoplasmic flows that accompany it. We also describe a unique interplay between Par proteins and the Hippo pathway in cleavage mammalian embryos. Moreover, we discuss the potential meaning of polarity, cytoplasmic dynamics and cell-to-cell communication as quality biomarkers of human embryos.
authors.affiliation: Department of Embryology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland mz205@cam.ac.uk aajduk@biol.uw.edu.pl.
authors.forename: Anna
authors.initials: A
authors.lastname: Ajduk
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK mz205@cam.ac.uk aajduk@biol.uw.edu.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Zernicka-Goetz
mesh_terms: D000818:Animals; D019521:Body Patterning; D017173:Caenorhabditis elegans / Q000166:cytology / Q000378:metabolism; D002450:Cell Communication; D002455:Cell Division / Q000235:genetics / Q000502:physiology*; D004330:Drosophila / Q000166:cytology / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology* / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D015398:Signal Transduction / Q000502:physiology
keywords: C. elegans; Drosophila; Hippo signalling; cytoplasmic flow; embryo; human; mouse; par proteins; polarity; preimplantation development