Polarized Myosin Produces Unequal-Size Daughters During Asymmetric Cell Division

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Science  30 Sep 2010:
DOI: 10.1126/science.1196112


Asymmetric positioning of the mitotic spindle before cytokinesis can produce different-sized daughter cells that have distinct fates. Here, we found an asymmetric division in the C. elegans Q neuroblast lineage that began with a centered spindle but generated different-sized daughters, the smaller (anterior) of which underwent apoptosis. During this division, more myosin II accumulated anteriorly, suggesting that asymmetric contractile forces might produce different-sized daughters. Indeed, partial inactivation of anterior myosin using chromophore-assisted laser inactivation created a more symmetric division and allowed the survival and differentiation of the anterior daughter. Thus, the balance of myosin activity on the two sides of a dividing cell can govern the size and fate of the daughters.