title: Higher Order Oligomerization of the Licensing ORC4 Protein Is Required for Polar Body Extrusion in Murine Meiosis.
abstract: We have previously shown that the DNA replication licensing factor ORC4 forms a cage around the chromosomes that are extruded in both polar bodies during murine oogenesis, but not around the chromosomes that are retained in the oocyte or around the sperm chromatin. We termed this structure the ORC4 cage. Here, we tested whether the formation of the ORC4 cage is necessary for polar body extrusion (PBE). We first experimentally forced oocytes to extrude sperm chromatin as a pseudo-polar body and found that under these conditions the sperm chromatin did become enclosed in an ORC4 cage. Next, we attempted to prevent the formation of the ORC4 cage by injecting peptides that contained sequences of different domains of the ORC4 protein into metaphase II (MII) oocytes just before the cage normally forms. Our rationale was that the ORC4 peptides would block protein-protein interactions required for cage formation. Two out of six tested peptides prevented the ORC4 cage formation and simultaneously inhibited PBE, resulting in the formation of two pronuclei (2 PN) that were retained in the oocyte. Together, these data demonstrate that ORC4 oligomerization is required to form the ORC4 cage and that it is required for PBE. J. Cell. Biochem. 118: 2941-2949, 2017. © 2017 Wiley Periodicals, Inc.
authors.affiliation: Department of Anatomy, Biochemistry and Physiology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii.
authors.forename: Hieu
authors.initials: H
authors.lastname: Nguyen
authors.affiliation: Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: James
authors.affiliation: Department of Anatomy, Biochemistry and Physiology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii.
authors.forename: Lynn
authors.initials: L
authors.lastname: Nguyen
authors.affiliation: Department of Anatomy, Biochemistry and Physiology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii.
authors.forename: Thien P
authors.initials: TP
authors.lastname: Nguyen
authors.affiliation: Department of Anatomy, Biochemistry and Physiology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii.
authors.forename: Cindy
authors.initials: C
authors.lastname: Vuong
authors.affiliation: University of Hawaii Cancer Center, University of Hawaii at Manoa, Honolulu, Hawaii.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Ortega
authors.affiliation: Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu.
authors.forename: David M
authors.initials: DM
authors.lastname: Jameson
authors.affiliation: Department of Anatomy, Biochemistry and Physiology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii.|Department of Obstetrics, Gynecology and Women's Health, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii.
authors.forename: W Steven
authors.identifier: 0000-0002-5025-192X
authors.initials: WS
authors.lastname: Ward
mesh_terms: D000818:Animals; D005260:Female; D008540:Meiosis / Q000502:physiology*; D051379:Mice; D051738:Origin Recognition Complex / Q000235:genetics / Q000378:metabolism*; D059705:Polar Bodies / Q000378:metabolism*; D055503:Protein Multimerization / Q000502:physiology*
chemical_list: C497231:Orc4 protein, mouse; D051738:Origin Recognition Complex
keywords: MEIOSIS; OOCYTE; ORC4; POLAR BODY EXTRUSION