title: Reversible disassembly of somatic nucleoli by the germ cell proteins FRGY2a and FRGY2b.
abstract: Egg cytoplasm has the capability to reprogramme differentiated somatic nuclei, as shown by nuclear transplantation in animal cloning. The nucleoli of donor nuclei are rapidly disassembled on injection into interphase eggs and are correctly reassembled when donor transcription initiates in the early embryos of frogs and mammals, recapitulating the physiological nucleolar dynamics of early embryogenesis. This is one of the most remarkable structural reorganizations of somatic nuclei in nuclear cloning. Despite the long history of nuclear cloning, almost nothing is known about the molecular mechanism of nucleolar disassembly in egg cytoplasm. Here we show that the Xenopus germ cell proteins FRGY2a and FRGY2b reversibly disassemble somatic nucleoli in egg cytoplasm, independently of continuing ribosomal RNA transcription. The carboxy-terminal domain of FRGY2a, which localizes to the nucleoli, is sufficient for nucleolar disassembly in transfected cells. Our results show that a single protein fragment can trigger reversible disassembly of the complex nucleolar structure.
authors.affiliation: Stem Cell Institute and Division of Hematology, Oncology and Transplantation, Department of Medicine, University of Minnesota, Mayo Mail Code 716, 420 Delaware Street, Minneapolis, Minnesota 55455, USA.
authors.forename: Koichi
authors.initials: K
authors.lastname: Gonda
authors.forename: Jason
authors.initials: J
authors.lastname: Fowler
authors.forename: Nobuko
authors.initials: N
authors.lastname: Katoku-Kikyo
authors.forename: Jennifer
authors.initials: J
authors.lastname: Haroldson
authors.forename: Justin
authors.initials: J
authors.lastname: Wudel
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Kikyo
mesh_terms: D000818:Animals; D002466:Cell Nucleolus / Q000378:metabolism / Q000648:ultrastructure*; D005854:Germ Cells / Q000378:metabolism*; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000378:metabolism / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014981:Xenopus; D029867:Xenopus Proteins / Q000378:metabolism / Q000502:physiology*
chemical_list: D020033:Protein Isoforms; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C075593:YBX2 protein, Xenopus