title: A contractile nuclear actin network drives chromosome congression in oocytes.
abstract: Chromosome capture by microtubules is widely accepted as the universal mechanism of spindle assembly in dividing cells. However, the observed length of spindle microtubules and computer simulations of spindle assembly predict that chromosome capture is efficient in small cells, but may fail in cells with large nuclear volumes such as animal oocytes. Here we investigate chromosome congression during the first meiotic division in starfish oocytes. We show that microtubules are not sufficient for capturing chromosomes. Instead, chromosome congression requires actin polymerization. After nuclear envelope breakdown, we observe the formation of a filamentous actin mesh in the nuclear region, and find that contraction of this network delivers chromosomes to the microtubule spindle. We show that this mechanism is essential for preventing chromosome loss and aneuploidy of the egg--a leading cause of pregnancy loss and birth defects in humans.
authors: Gene Expression and Cell Biology/Biophysics Programmes, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
authors: Péter
authors: P
authors: Lénárt
authors: Christian P
authors: CP
authors: Bacher
authors: Nathalie
authors: N
authors: Daigle
authors: Arthur R
authors: AR
authors: Hand
authors: Roland
authors: R
authors: Eils
authors: Mark
authors: M
authors: Terasaki
authors: Jan
authors: J
authors: Ellenberg
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D020090:Chromosome Segregation / Q000187:drug effects; D002875:Chromosomes / Q000187:drug effects / Q000502:physiology*; D008540:Meiosis; D018613:Microscopy, Confocal; D008870:Microtubules / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D013045:Species Specificity; D013215:Starfish; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
chemical_list: D000199:Actins; D001704:Biopolymers; D019086:Bridged Bicyclo Compounds, Heterocyclic; D013844:Thiazoles; D053778:Thiazolidines; C037068:latrunculin B; D015739:Nocodazole