title: Spindle-to-cortex communication in cleaving, polyspermic Xenopus eggs.
abstract: Mitotic spindles specify cleavage planes in early embryos by communicating their position and orientation to the cell cortex using microtubule asters that grow out from the spindle poles during anaphase. Chromatin also plays a poorly understood role. Polyspermic fertilization provides a natural experiment in which aster pairs from the same spindle (sister asters) have chromatin between them, whereas asters pairs from different spindles (nonsisters) do not. In frogs, only sister aster pairs induce furrows. We found that only sister asters recruited two conserved furrow-inducing signaling complexes, chromosome passenger complex (CPC) and Centralspindlin, to a plane between them. This explains why only sister pairs induce furrows. We then investigated factors that influenced CPC recruitment to microtubule bundles in intact eggs and a cytokinesis extract system. We found that microtubule stabilization, optimal starting distance between asters, and proximity to chromatin all favored CPC recruitment. We propose a model in which proximity to chromatin biases initial CPC recruitment to microtubule bundles between asters from the same spindle. Next a positive feedback between CPC recruitment and microtubule stabilization promotes lateral growth of a plane of CPC-positive microtubule bundles out to the cortex to position the furrow.
authors: Department of Systems Biology, Harvard Medical School, Boston, MA 02115; Marine Biological Laboratory, Woods Hole, MA 02143 Christine_Field@hms.harvard.edu.
authors: Christine M
authors: CM
authors: Field
authors: Department of Systems Biology, Harvard Medical School, Boston, MA 02115; Marine Biological Laboratory, Woods Hole, MA 02143.
authors: Aaron C
authors: AC
authors: Groen
authors: Department of Systems Biology, Harvard Medical School, Boston, MA 02115; Marine Biological Laboratory, Woods Hole, MA 02143.
authors: Phuong A
authors: PA
authors: Nguyen
authors: Department of Systems Biology, Harvard Medical School, Boston, MA 02115; Marine Biological Laboratory, Woods Hole, MA 02143.
authors: Timothy J
authors: TJ
authors: Mitchison
mesh_terms: D000705:Anaphase / Q000502:physiology; D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D002843:Chromatin / Q000378:metabolism; D048749:Cytokinesis / Q000502:physiology; D005260:Female; D005306:Fertilization / Q000502:physiology*; D008870:Microtubules / Q000502:physiology; D010063:Ovum / Q000502:physiology*; D008941:Spindle Apparatus / Q000378:metabolism / Q000502:physiology*; D014981:Xenopus / Q000502:physiology*; D015053:Zygote / Q000502:physiology
chemical_list: D002843:Chromatin