Disrupting hedgehog and WNT signaling interactions promotes cleft lip pathogenesis
Hiroshi Kurosaka, … , Trevor Williams, Paul A. Trainor
Hiroshi Kurosaka, … , Trevor Williams, Paul A. Trainor
Published March 3, 2014
Citation Information: J Clin Invest. 2014;124(4):1660-1671. https://doi.org/10.1172/JCI72688.
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Research Article Cell biology

Disrupting hedgehog and WNT signaling interactions promotes cleft lip pathogenesis

Abstract

Cleft lip, which results from impaired facial process growth and fusion, is one of the most common craniofacial birth defects. Many genes are known to be involved in the etiology of this disorder; however, our understanding of cleft lip pathogenesis remains incomplete. In the present study, we uncovered a role for sonic hedgehog (SHH) signaling during lip fusion. Mice carrying compound mutations in hedgehog acyltransferase (Hhat) and patched1 (Ptch1) exhibited perturbations in the SHH gradient during frontonasal development, which led to hypoplastic nasal process outgrowth, epithelial seam persistence, and cleft lip. Further investigation revealed that enhanced SHH signaling restricts canonical WNT signaling in the lambdoidal region by promoting expression of genes encoding WNT inhibitors. Moreover, reduction of canonical WNT signaling perturbed p63/interferon regulatory factor 6 (p63/IRF6) signaling, resulting in increased proliferation and decreased cell death, which was followed by persistence of the epithelial seam and cleft lip. Consistent with our results, mutations in genes that disrupt SHH and WNT signaling have been identified in both mice and humans with cleft lip. Collectively, our data illustrate that altered SHH signaling contributes to the etiology and pathogenesis of cleft lip through antagonistic interactions with other gene regulatory networks, including the canonical WNT and p63/IRF6 signaling pathways.

Authors

Hiroshi Kurosaka, Angelo Iulianella, Trevor Williams, Paul A. Trainor

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Figure 3

Cell death and proliferation in epithelial seams of E11.5 Hhatcreface Ptch1wiggable embryos.

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Cell death and proliferation in epithelial seams of E11.5 Hhatcreface Pt...
(A–F) TUNEL staining (green) with ECAD immunolabeling (red) in E11.5 control and Hhatcreface Ptch1wiggable embryo FNPs. (A–C) Control embryo epithelial seam cells underwent cell death and diminished ECAD immunostaining to remove the epithelial cells (white arrow). (D–F) Hhatcreface Ptch1wiggable embryos showed thicker epithelial seam and lacked proper cell death (white arrow). (G–L) Immunolabeling of phospho-histone H3 (green) and ECAD (red) in E11.5 control and Hhatcreface Ptch1wiggable embryo FNPs. (G–I) Very few proliferating cells could be detected in control embryo epithelial seams. (J–L) In contrast, increased cell proliferation was detected in Hhatcreface Ptch1wiggable embryo epithelial seam cells (yellow arrowheads). (O) Statistical analysis showed significant difference in number of proliferating cells between Hhatcreface Ptch1wiggable (MT) and control embryos. (P) Percentage of apoptotic cells in epithelial seam cells of control and Hhatcreface Ptch1wiggable embryos. *P < 0.05, Student’s t test. Data are represented as mean ± SEM. (M and N) Each yellow line indicates which plane was used in these images. Scale bars: 50 μm.