Symmetric cell division of the mouse zygote requires an actin network

Authors

  • Ting Gang Chew,

    Corresponding author
    1. Mammalian Development Laboratory, Institute of Medical Biology, A-STAR, Singapore
    • Mammalian Development Laboratory, Institute of Medical Biology, 8A Biomedical Grove, #06-06 Immunos, Singapore 138648
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    • T.G.C. and C.L. contributed equally to this work

  • Chanchao Lorthongpanich,

    1. Mammalian Development Laboratory, Institute of Medical Biology, A-STAR, Singapore
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    • T.G.C. and C.L. contributed equally to this work

  • Wei Xia Ang,

    1. Mammalian Development Laboratory, Institute of Medical Biology, A-STAR, Singapore
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  • Barbara B. Knowles,

    1. Mammalian Development Laboratory, Institute of Medical Biology, A-STAR, Singapore
    2. Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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  • Davor Solter

    1. Mammalian Development Laboratory, Institute of Medical Biology, A-STAR, Singapore
    2. Duke-NUS Graduate Medical School, Singapore
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  • Monitoring Editor: Roberto Dominguez

Abstract

Positioning of the cleavage plane is regulated to ensure proper animal development. Most animal cells rely on the astral microtubules to position the mitotic spindle, which in turn specifies the cleavage plane. The mouse zygote lacks discernible astral microtubules but still divides symmetrically. Here, we demonstrate a cloud-like accumulation of F-actin surrounds the spindle in zygotes and when this actin network is disassembled, the spindle assumes an off-center position, and the resulting zygote divides asymmetrically into two unequal size blastomeres. Interestingly, when the spindle is micromanipulated to the subcortical region, the zygote without the actin network is unable to reposition the spindle and cleavage plane at the cell center. This study reveals that an actin network maintains the central spindle position in anastral mitosis, and ensures the first embryonic mitosis is symmetrical. © 2012 Wiley Periodicals, Inc

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