Wnt Signaling Interacts with Bmp and Edn1 to Regulate Dorsal-Ventral Patterning and Growth of the Craniofacial Skeleton

Abstract

Craniofacial development requires signals from epithelia to pattern skeletogenic neural crest (NC) cells, such as the subdivision of each pharyngeal arch into distinct dorsal (D) and ventral (V) elements. Wnt signaling has been implicated in many aspects of NC and craniofacial development, but its roles in D-V arch patterning remain unclear. To address this we blocked Wnt signaling in zebrafish embryos in a temporally-controlled manner, using transgenics to overexpress a dominant negative Tcf3, (dntcf3), (Tg(hsp70I:tcf3-GFP), or the canonical Wnt inhibitor dickkopf1 (dkk1), (Tg(hsp70i:dkk1-GFP) after NC migration. In dntcf3 transgenics, NC cells in the ventral arches of heat-shocked embryos show reduced proliferation, expression of ventral patterning genes (hand2, dlx3b, dlx5a, msxe), and ventral cartilage differentiation (e.g. lower jaws). These D-V patterning defects resemble the phenotypes of zebrafish embryos lacking Bmp or Edn1 signaling, and overexpression of dntcf3 dramatically reduces expression of a subset of Bmp receptors in the arches. Addition of ectopic BMP (or EDN1) protein partially rescues ventral development and expression of dlx3b, dlx5a, and msxe in Wnt signaling-deficient embryos, but surprisingly does not rescue hand2 expression. Thus Wnt signaling provides ventralizing patterning cues to arch NC cells, in part through regulation of Bmp and Edn1 signaling, but independently regulates hand2. Similarly, heat-shocked dkk1+ embryos exhibit ventral arch reductions, but also have mandibular clefts at the ventral midline not seen in dntcf3+ embryos. Dkk1 is expressed in pharyngeal endoderm, and cell transplantation experiments reveal that dntcf3 must be overexpressed in pharyngeal endoderm to disrupt D-V arch patterning, suggesting that distinct endodermal roles for Wnts and Wnt antagonists pattern the developing skeleton.

Distinct requirements of wls , wnt9a , wnt5b and gpc4 in regulating chondrocyte maturation and timing of endochondral ossification

“…In ventral cartilage development, Wnt signaling is required for early CNCC induction and later in CNCC migration, specification and proliferation by participating in a gene regulatory network with Edn1 and Bmp (Alexander et al, 2014). Heat-shock studies inhibiting Wnt through the overexpression of dkk1, a Wnt antagonist and dntcf3, a dominant negative form of the Tcf3 transcription factor, showed ventral patterning defects in the mandibular arch (Alexander et al, 2014).…”

“…Heat-shock studies inhibiting Wnt through the overexpression of dkk1, a Wnt antagonist and dntcf3, a dominant negative form of the Tcf3 transcription factor, showed ventral patterning defects in the mandibular arch (Alexander et al, 2014). Recent studies using Wls to manipulate Wnt signaling, implicated its role in skeletal development by regulating osteogenesis and chondrogenesis (Maruyama et al, 2013; Rochard et al, 2016; Zhong et al, 2012).…”

Systematic review of hormonal and genetic factors involved in the nonsyndromic disorders of the lower jaw

“…Based on the search results, previous studies showed that Wnt/ß‐catenin induces BMP/EDN1 as well as TGFß3 expression, important for ventralizing patterning and mesenchymal differentiation, whereas BMP and FGF induce SOX9 and SOX10, which are responsible for chondrogenic activation (Alexander et al, ; Jayasena and Bronner, ; Jin et al, ). Previous studies on regulatory pathways showed that TGFß and BMP signaling induce and control osteogenic gene expression (Gu et al, ; He et al, ; Jayasena and Bronner, ; Song et al, ).…”

Pharyngeal morphogenesis requires fras1 - itga8 -dependent epithelial-mesenchymal interaction

“…8D). Arch patterning occurs between 20 and 30-36 hpf, when pharyngeal arch mesenchyme is divided into major domains by signaling and transcription factors (Alexander et al, 2014; Miller, 2003; Miller et al, 2000; Nichols et al, 2013; Talbot et al, 2010; Zuniga et al, 2010). During this same phase, early endodermal pouch-1 forms (Schilling and Kimmel, 1994) and is a rich source of patterning signals (Choe and Crump, 2015).…”