First published online April 13, 2005
Development 132, 906e (2005)
© The Company of Biologists Limited
Six-free, muscle-free mice
In mice, the homeoproteins Six4 and Six1 are co-expressed during myogenesis
in the myotome, limb bud mesenchyme and other muscle precursors. However,
although Six1-null mouse embryos show some mild muscle defects,
muscle development is normal in Six4-null mice. On p.
2235, Grifone and
co-workers report that the muscle defect seen in Six1-null mice is
amplified in Six1 Six4 double knockout mice. These mice have no limb
muscles because Pax3 is downregulated in a ventral region of the
somites that gives rise to the progenitors of the hypaxial muscle, from which
limb muscles form. Consequently, the muscle precursors fail to migrate
properly, lose their myogenic identity and apoptose. The researchers also
detail how the absence of Six1 and Six4 affects myogenic
regulatory factors throughout the developing musculature and conclude that the
overlapping functions of Six1 and Six4 play several different roles during
skeletal myogenesis.
Related articles in Development:
- Six1 and Six4 homeoproteins are required for Pax3 and Mrf expression during myogenesis in the mouse embryo
- Raphaelle Grifone, Josiane Demignon, Christophe Houbron, Evelyne Souil, Claire Niro, Mary J. Seller, Ghislaine Hamard, and Pascal Maire
Development 2005 132: 2235-2249.
[Abstract]
[Full Text]
