First published online June 20, 2008
Development 135, 1402e (2008)
© The Company of Biologists Limited
Myosin IIB: a force for morphogenesis
Two tissue movements - convergence and extension - are essential for axial
morphogenesis in vertebrate and invertebrate embryos. But what generates the
tensile forces that drive the intercalation of cells that underlies these two
movements? On p.
2435, Skoglund and colleagues report that in Xenopus laevis
embryos, convergence and extension at gastrulation require a myosin
IIB-dependent cortical actin network. Using morpholino knockdown, they show
that myosin IIB (a cytoskeletal myosin that crosslinks actin filaments and
acts as a molecular motor) is needed during gastrulation to maintain a
stereotypical cortical actin cytoskeleton. This network is polarized relative
to the embryonic axis, the researchers report, and cyclically lengthens and
shortens during gastrulation. Depletion of myosin IIB also results in the loss
of the polarized protrusive activity usually seen in intercalating cells, the
loss of cell-cell and cell-matrix adhesion, and failure of blastopore closure.
Together, these findings reveal how a molecular-scale motor protein can
generate the tensile forces that drive tissue-scale embryonic
morphogenesis.

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Related articles in Development:
- Convergence and extension at gastrulation require a myosin IIB-dependent cortical actin network
- Paul Skoglund, Ana Rolo, Xuejun Chen, Barry M. Gumbiner, and Ray Keller
Development 2008 135: 2435-2444.
[Abstract]
[Full Text]