Ectopic Hedgehog Signaling Causes Cleft Palate and Defective Osteogenesis

• Published in: Journal of dental research Vol. 97; no. 13; pp. 1485 - 1493
• Main Authors: Hammond, N.L., Brookes, K.J., Dixon, M.J.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01-12-2018; SAGE PUBLICATIONS, INC
• Subjects: Animals; Bone growth; Bone morphogenetic proteins; Bone Morphogenetic Proteins - metabolism; Cell Proliferation; Cleft lip/palate; Cleft Palate - embryology; Cleft Palate - genetics; Congenital defects; Defects; Embryonic Development - genetics; Extracellular Matrix Proteins - metabolism; Forkhead Transcription Factors - metabolism; Gene expression; Gene Expression Regulation, Developmental; Hedgehog protein; Hedgehog Proteins - metabolism; Mandible - abnormalities; Mandible - embryology; Mesenchyme; Mesoderm - embryology; Mice; Mutation; Mutation - genetics; Neural crest; Neural Crest - embryology; Osteogenesis; Osteogenesis - physiology; Pattern formation; Research Reports; Signal Transduction; Smoothened Receptor - metabolism; Transcription factors; Wnt protein; Wnt Signaling Pathway - physiology; wnt signaling pathway; sonic hedgehog; craniofacial abnormalities; micrognathism; neural crest; bone morphogenetic proteins
• ISSN: 0022-0345; 1544-0591
• DOI: 10.1177/0022034518785336

Cleft palate is a common birth defect that frequently occurs in human congenital malformations caused by mutations in components of the Sonic Hedgehog (SHH) signaling cascade. Shh is expressed in dynamic, spatiotemporal domains within epithelial rugae and plays a key role in driving epithelial-mesenchymal interactions that are central to development of the secondary palate. However, the gene regulatory networks downstream of Hedgehog (Hh) signaling are incompletely characterized. Here, we show that ectopic Hh signaling in the palatal mesenchyme disrupts oral-nasal patterning of the neural crest cell–derived ectomesenchyme of the palatal shelves, leading to defective palatine bone formation and fully penetrant cleft palate. We show that a series of Fox transcription factors, including the novel direct target Foxl1, function downstream of Hh signaling in the secondary palate. Furthermore, we demonstrate that Wnt/bone morphogenetic protein (BMP) antagonists, in particular Sostdc1, are positively regulated by Hh signaling, concomitant with downregulation of key regulators of osteogenesis and BMP signaling effectors. Our data demonstrate that ectopic Hh-Smo signaling downregulates Wnt/BMP pathways, at least in part by upregulating Sostdc1, resulting in cleft palate and defective osteogenesis.