Overlapping functions of SIX homeoproteins during embryonic myogenesis

by Maud Wurmser, Rouba Madani, Nathalie Chaverot, St éphanie Backer, Matthew Borok, Matthieu Dos Santos, Glenda Comai, Shahragim Tajbakhsh, Frédéric Relaix, Marc Santolini, Ramkumar Sambasivan, Rulang Jiang, Pascal Maire Four SIX homeoproteins display a combinatorial expression throughout embryonic developmental myogenesis and they modulate the expression of the myogenic regulatory factors. Here, we provide a deep characterization of their role in distinct mouse developmental territories. We showed, at the hypaxial level, that theSix1:Six4 double knockout (dKO) somitic precursor cells adopt a smooth muscle fate and lose their myogenic identity. At the epaxial level, we demonstrated by the analysis ofSix quadruple KO (qKO) embryos, that SIX are required for fetal myogenesis, and for the maintenance of PAX7+ progenitor cells, which differentiated prematurely and are lost by the end of fetal development in qKO embryos. Finally, we showed thatSix1 andSix2 are required to establish craniofacial myogenesis by controlling the expression ofMyf5. We have thus described an unknown role for SIX proteins in the control of myogenesis at different embryonic levels and refined their involvement in the genetic cascades operating at the head level and in the genesis of myogenic stem cells.
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research