Histochemistry and Cell Biology

, Volume 138, Issue 3, pp 503–514

Divergent regulation of Wnt-mediated development of the dorsomedial and ventrolateral dermomyotomal lips

Original Paper

DOI: 10.1007/s00418-012-0971-y

Cite this article as:
Krück, S. & Scaal, M. Histochem Cell Biol (2012) 138: 503. doi:10.1007/s00418-012-0971-y
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Abstract

The dermomyotome is the dorsal compartment of the somite which gives rise to multiple cell fates including skeletal muscle, connective tissue, and endothelia. It consists of a pseudostratified, roughly rectangular epithelial sheet, the margins of which are called the dermomyotomal lips. The dermomyotomal lips are blastema-like epithelial growth zones, which continuously give rise to resident dermomyotomal cells and emigrating muscle precursor cells, which populate the subjacent myotomal compartment. Wnt signaling has been shown to regulate both dermomyotome formation and maintenance of the dermomyotomal lips. Whereas the epithelialization of the dermomyotome is regulated via canonical, β-catenin-dependent Wnt signaling, the downstream signaling mechanisms suppressing epithelial–mesenchymal transition (EMT) in the mature dermomyotomal lips have been unknown. Here, we present evidence that dermomyotomal lip sustainment is differentially regulated. Whereas the dorsomedial dermomyotomal lip is maintained by canonical Wnt signaling, development of the ventrolateral dermomyotomal lip is regulated by non-canonical, PCP-like Wnt signaling. We discuss our results in the light of the different developmental prerequisites in the dorsomedial and ventrolateral lips, respectively, thus providing a new perspective on the regulation of dermomyotomal EMT.

Keywords

WntSomiteDermomyotomeEMT

Supplementary material

418_2012_971_MOESM1_ESM.pptx (99 kb)
Schematic representation of the electroporation procedure used to transfect dermomyotomal lip cells. Note that the position of the electrodes (+ and −) is merely diagrammed to visualise the electric current flow. In the experimental setup both electrodes are positioned on top of the ectoderm by manual bending of the embryo (see Scaal et al. 2004 for details). Electroporation of DML precursor cells in the dorsomedial (prospective DML, a) or dorsolateral (prospective VLL, b) quadrant of the epithelial somite (solid green). Plasmid solution (hatched green) is injected into the somitocoele. Electroporation of mature DML (c) and VLL (d), both coloured by solid green. Plasmid solution (hatched green) is injected into the sub-lip domain underneath the corresponding dermomyotomal lip. Supplementary material 1 (PPTX 98 kb)
418_2012_971_MOESM2_ESM.pdf (169 kb)
Control electroporations using solely a GFP reporter vector to demonstrate that a successful electroporation procedure alone does not specifically alter dermomyotomal morphology. Panels from left to right expression of the GFP reporter in overview, in situ hybridization showing Pax3-expression in the same embryo in overview, in situ hybridization showing Pax3-expression in the same embryo in detail, vibratome section through the electroporated region showing in situ hybridization for Pax3, paraffine section through the electroporated region showing immunohistochemical localization of the epithelial marker Connexin43, paraffine section showing immunohistochemical localization of the GFP reporter in the same section. Electroporation at HH-stages 14–15 (epithelial somites) and 16–17 (mature somites), reincubation 24 h. af Electroporation of GFP in DML precursor cells in the epaxial dorsal quadrant of an epithelial somite does not specifically alter the morphology of the DML. gl Electroporation of GFP in VLL precursor cells in the hypaxial dorsal quadrant of an epithelial somite does not specifically alter the morphology of the VLL. mr Electroporation of GFP in mature DML cells does not specifically alter the morphology of the DML. sx Electroporation of GFP in mature VLL cells does not specifically alter the morphology of the VLL. Scale bar 150 μm. Supplementary material 2 (PDF 168 kb)
418_2012_971_MOESM3_ESM.pdf (84 kb)
In situ hybridizations for various members of Wnt signalling pathways in the dermomyotome of chicken embryos. Transversal sections at the level of an intermediate stage dermomyotome, dorsal to the top, axial organs to the left. Note that the canonical downstream effector beta-catenin is expressed mainly in the DML (a), whereas the non-canonical downstream component Prickle1 is expressed in the myotome and in the VLL (b). Mutually exclusive expression pattern of Frizzled receptors, as Frizzled1 is expressed in the VLL (c), whereas Frizzled7 is expressed in the DML (d). Scale bar 150 μm. Supplementary material 3 (PDF 83 kb)

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Department of Molecular Embryology, Institute of Anatomy and Cell BiologyUniversity of FreiburgFreiburgGermany
  2. 2.Institute of Anatomy IIUniversity of CologneCologneGermany