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Dev Cell 2012 Apr 17;224:775-87. doi: 10.1016/j.devcel.2012.01.002.
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Spindle position in symmetric cell divisions during epiboly is controlled by opposing and dynamic apicobasal forces.

Orientation of cell division is a vital aspect of tissue morphogenesis and growth. Asymmetric divisions generate cell fate diversity and epithelial stratification, whereas symmetric divisions contribute to tissue growth, spreading, and elongation. Here, we describe a mechanism for positioning the spindle in symmetric cell divisions of an embryonic epithelium. We show that during the early stages of epiboly, spindles in the epithelium display dynamic behavior within the plane of the epithelium but are kept firmly within this plane to give a symmetric division. This dynamic stability relies on balancing counteracting forces: an apically directed force exerted by F-actin/myosin-2 via active cortical flow and a basally directed force mediated by microtubules and myosin-10. When both forces are disrupted, spindle orientation deviates from the epithelial plane, and epithelial surface is reduced. We propose that this dynamic mechanism maintains symmetric divisions while allowing the quick adjustment of division plane to facilitate even tissue spreading.

PubMed ID: 22406140
PMC ID: PMC3332010
Article link: Dev Cell
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: actl6a ctrl h2bc21 myh4 myh6 myo10 myo10.2 noct nr2e1 rho tjp1
Antibodies: Ctnnb1 Ab5 Phosphorylated myosin light chain Ab2 Tuba4b Ab2
Morpholinos: myh10 MO1 myo10.2 MO5

Phenotypes: Xla Wt + GFP-myo10.2 (fig.S3.b, c) [+]

Article Images: [+] show captions
References [+] :
Baena-López, The orientation of cell divisions determines the shape of Drosophila organs. 2005, Pubmed