title: Downregulation of Par3 and aPKC function directs cells towards the ICM in the preimplantation mouse embryo.
abstract: Generation of inside cells that develop into inner cell mass (ICM) and outside cells that develop into trophectoderm is central to the development of the early mouse embryo. Critical to this decision is the development of cell polarity and the associated asymmetric (differentiative) divisions of the 8-cell-stage blastomeres. The underlying molecular mechanisms for these events are not understood. As the Par3/aPKC complex has a role in establishing cellular polarity and division orientation in other systems, we explored its potential function in the developing mouse embryo. We show that both Par3 and aPKC adopt a polarized localization from the 8-cell stage onwards and that manipulating their function re-directs cell positioning and consequently influences cell fate. Injection of dsRNA against Par3 or mRNA for a dominant negative form of aPKC into a random blastomere at the 4-cell stage directs progeny of the injected cell into the inside part of the embryo. This appears to result from both an increased frequency by which such cells undertake differentiative divisions and their decreased probability of retaining outside positions. Thus, the natural spatial allocation of blastomere progeny can be over-ridden by downregulation of Par3 or aPKC, leading to a deceased tendency for them to remain outside and so develop into trophectoderm. In addition, this experimental approach illustrates a powerful means of manipulating gene expression in a specific clonal population of cells in the preimplantation embryo.
authors.affiliation: Wellcome Trust and Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QR, UK.
authors.forename: Berenika
authors.initials: B
authors.lastname: Plusa
authors.forename: Stephen
authors.initials: S
authors.lastname: Frankenberg
authors.forename: Andrew
authors.initials: A
authors.lastname: Chalmers
authors.forename: Anna-Katerina
authors.initials: AK
authors.lastname: Hadjantonakis
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Moore
authors.forename: Nancy
authors.initials: N
authors.lastname: Papalopulu
authors.forename: Virginia E
authors.initials: VE
authors.lastname: Papaioannou
authors.forename: David M
authors.initials: DM
authors.lastname: Glover
authors.forename: Magdalena
authors.initials: M
authors.lastname: Zernicka-Goetz
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001755:Blastocyst / Q000166:cytology* / Q000378:metabolism; D001757:Blastomeres / Q000166:cytology / Q000378:metabolism; D019521:Body Patterning / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity / Q000502:physiology; D002970:Cleavage Stage, Ovum / Q000166:cytology / Q000502:physiology; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D062793:Occludin; D010750:Phosphoproteins / Q000032:analysis; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000008:administration & dosage / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019108:Tight Junctions / Q000737:chemistry / Q000378:metabolism; D062826:Zonula Occludens-1 Protein; D000099293:Protein Kinase C-lambda
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015815:Cell Adhesion Molecules; D018797:Cell Cycle Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D062793:Occludin; D010750:Phosphoproteins; D011493:Protein Kinase C; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D062826:Zonula Occludens-1 Protein; D000099293:Protein Kinase C-lambda; C568986:Ocln protein, mouse; C115084:Pard3 protein, mouse; C569043:Tjp1 protein, mouse