title: Pre-assembled Nuclear Pores Insert into the Nuclear Envelope during Early Development.
abstract: Nuclear pore complexes (NPCs) span the nuclear envelope (NE) and mediate nucleocytoplasmic transport. In metazoan oocytes and early embryos, NPCs reside not only within the NE, but also at some endoplasmic reticulum (ER) membrane sheets, termed annulate lamellae (AL). Although a role for AL as NPC storage pools has been discussed, it remains controversial whether and how they contribute to the NPC density at the NE. Here, we show that AL insert into the NE as the ER feeds rapid nuclear expansion in Drosophila blastoderm embryos. We demonstrate that NPCs within AL resemble pore scaffolds that mature only upon insertion into the NE. We delineate a topological model in which NE openings are critical for AL uptake that nevertheless occurs without compromising the permeability barrier of the NE. We finally show that this unanticipated mode of pore insertion is developmentally regulated and operates prior to gastrulation.
authors.affiliation: European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hampoelz
authors.affiliation: European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.
authors.forename: Marie-Therese
authors.initials: MT
authors.lastname: Mackmull
authors.affiliation: European Molecular Biology Laboratory, Electron Microscopy Core Facility, 69117 Heidelberg, Germany.
authors.forename: Pedro
authors.initials: P
authors.lastname: Machado
authors.affiliation: European Molecular Biology Laboratory, Electron Microscopy Core Facility, 69117 Heidelberg, Germany.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ronchi
authors.affiliation: European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.
authors.forename: Khanh Huy
authors.initials: KH
authors.lastname: Bui
authors.affiliation: European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, 69117 Heidelberg, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Schieber
authors.affiliation: European Molecular Biology Laboratory, Electron Microscopy Core Facility, 69117 Heidelberg, Germany.
authors.forename: Rachel
authors.initials: R
authors.lastname: Santarella-Mellwig
authors.affiliation: European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Necakov
authors.affiliation: European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.
authors.forename: Amparo
authors.initials: A
authors.lastname: Andrés-Pons
authors.affiliation: Aix-Marseille Université, CNRS, IBDM UMR 7288, 13009 Marseille, France.
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Philippe
authors.affiliation: Aix-Marseille Université, CNRS, IBDM UMR 7288, 13009 Marseille, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lecuit
authors.affiliation: European Molecular Biology Laboratory, Electron Microscopy Core Facility, 69117 Heidelberg, Germany; European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, 69117 Heidelberg, Germany.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Schwab
authors.affiliation: European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany; European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, 69117 Heidelberg, Germany. Electronic address: martin.beck@embl.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Beck
mesh_terms: D000818:Animals; D001756:Blastoderm / Q000378:metabolism / Q000648:ultrastructure; D004330:Drosophila; D004625:Embryo, Nonmammalian / Q000378:metabolism* / Q000648:ultrastructure; D047108:Embryonic Development; D004721:Endoplasmic Reticulum / Q000378:metabolism; D054262:Gastrulation; D009685:Nuclear Envelope / Q000378:metabolism*; D022022:Nuclear Pore / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure