Multimodal transcriptomic profiling of the embryonic palate enables novel in utero cleft therapy [bulk RNA-Seq]
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ABSTRACT: Cleft palate is a common disorder of development resulting from failure of growth, migration, elevation, and osteogenic fusion of embryonic cranial neural crest-derived palatal shelves. Despite progress in recent decades, the molecular pathways involved in this failure are not well understood. Here, we present a multimodal, spatiotemporal transcriptomic profiling of the developing palate through integrated, unbiased single-cell and bulk RNA-sequencing and multiplexed in situ mRNA mapping of osteogenic cell lineages. We then show that loss of Pax9, a critical transcription factor orchestrator of Wnt signaling in palate development, results in increased expression of sclerostin (Sost), a known antagonist of Wnt signaling. Finally, we reveal that a single dose of sclerostin-neutralizing monoclonal antibody restores Wnt signaling and corrects cleft palate defects in utero in Pax9-/- mouse embryos.
Project description:Cleft palate is a common disorder of development resulting from failure of growth, migration, elevation, and osteogenic fusion of embryonic cranial neural crest-derived palatal shelves. Despite progress in recent decades, the molecular pathways involved in this failure are not well understood. Here, we present a multimodal, spatiotemporal transcriptomic profiling of the developing palate through integrated, unbiased single-cell and bulk RNA-sequencing and multiplexed in situ mRNA mapping of osteogenic cell lineages. We then show that loss of Pax9, a critical transcription factor orchestrator of Wnt signaling in palate development, results in increased expression of sclerostin (Sost), a known antagonist of Wnt signaling. Finally, we reveal that a single dose of sclerostin-neutralizing monoclonal antibody restores Wnt signaling and corrects cleft palate defects in utero in Pax9-/- mouse embryos.
Project description:Nonsyndromic clefts of the palate and/or lip are common birth defects arising in about 1/700 live births worldwide. They are caused by multiple genetic and environmental factors, can only be corrected surgically and require complex post-operative care that imposes significant burdens on individuals and society. Our understanding of the molecular networks that control palatogenesis has advanced through studies on mouse genetic models of cleft palate. In particular, the transcription factor Pax9 regulates palatogenesis through the Bmp, Fgf and Shh pathways in mice. But there is still much to learn about Pax9's relationship with other signaling pathways in this process. Here we show alterations of Wnt expression and decreased Wnt activity in Pax9-/- palatal shelves are a likely result of Pax9's ability to directly bind and repress the promoters of Dkk1 and Dkk2, proteins that antagonize Wnt signaling. We exploited this relationship by delivering small-molecule Dkk inhibitors into the tail-veins of pregnant Pax9+/- females from E10.5 to E14.5. Such therapies restored Wnt signaling, promoted cell proliferation, bone formation and fusion of palatal shelves in Pax9-/- embryos. These data uncover a connection between the roles of Pax9 and Wnt genes in palatogenesis and offer a new approach for treating human cleft palates.
Project description:Cleft palate is a common congenital anomaly with a live birth prevalence estimated to be 1:2500 live births, that results from failure of growth, elevation, adhesion and/or fusion of the palatal shelves during embryogenesis. Mutations in the gene encoding the transcription factor p63 result in cleft palate in humans and mice. To study the roles of P63 in periderm migration and medial edge epithelia in mice sub-mucous cleft palate, ÎNp63alpha was ectopically expressed in the palatal epithelia using a transgenic approach.
Project description:In this study, we have investigated the molecular basis of Shh signalling during development of the secondary palate and how CNCC patterning and fate is influenced by the Shh signalling network. Using a gain-of-function mouse model to activate Smoothened (R26SmoM2) signalling in the palatal mesenchyme (Osr2-IresCre), we demonstrate ectopic Hh-Smo signalling results in fully penetrant cleft palate, disrupted oral-nasal patterning and defective palatine bone formation. We show that a series of Fox transcription factors, including the novel direct target Foxl1, function downstream of Hh signalling in the secondary palate. Furthermore, we demonstrate that Wnt/BMP antagonists, in particular Sostdc1, are positively regulated by Hh signalling, concomitant with down-regulation of key regulators of osteogenesis and BMP signalling effectors. Microarray analysis was performed on excised palatal shelves from Osr2-IresCre+/- (wild-type) and Osr2-IresCre;Smo+/M2 (mutant) embryos at embryonic day (E)13.5. Osr2-IresCre (PMID:17941042) and R26SmoM2 (PMID:15107405) mice have been described previously.
Project description:Tamoxifen (TAM), a widely-used drug in treating breast cancer, has been reported to be associated with craniofacial defects including micrognathia and cleft palate in humans. However, the exact effects of TAM on the developing palate remain unclear. In the present study, we conclude that excess TAM exposure causes cleft palate defect in mice by regulating MAPK pathways, which implicates the importance of tightly regulated MAPK signaling in palate development and provides a basis for further exploration of the molecular etiology of cleft palate defects caused by environmental factors.
Project description:Nonsyndromic clefts of the palate and/or lip are common birth defects arising in about 1/700 live births worldwide. They are caused by multiple genetic and environmental factors, can only be corrected surgically and require complex post-operative care that imposes significant burdens on individuals and society. Our understanding of the molecular networks that control palatogenesis has advanced through studies on mouse genetic models of cleft palate. In particular, the transcription factor Pax9 regulates palatogenesis through the Bmp, Fgf and Shh pathways in mice. But there is still much to learn about Pax9’s relationship with other signaling pathways in this process. Expression analyses and unbiased gene expression profiling studies offer a molecular explanation for the resolution of palatal defects by showing that Wnt and Eda/Edar-related genes are expressed in normal palatal tissues and that the Wnt and Eda/Edar signaling pathway is downstream of Pax9 in palatogenesis.
Project description:Despite advances in understanding the morphological disruptions that lead to defects in palate formation, the precise perturbations within the signaling microenvironment of palatal clefts remain poorly understood. To explore in greater depth the genomic basis of palatal clefts, we designed and implemented the first single cell spatial RNA-sequencing study in a cleft palate model, utilizing the Pax9-/- murine model at multiple developmental timepoints, which exhibits a consistent cleft palate defect. A novel platform for true single-cell resolution spatially resolved transcriptomics (Visium HD, 10x Genomics, Inc.) was employed using custom bins of 2x2 µm spatial gene expression data, then validated using Xenium In Situ mRNA spatial profiling and RNAscope Multiplex. Functional enrichment analysis revealed a palate cell-specific perturbation in Wnt signaling effector function in tandem with disrupted expression of extracellular matrix genes in developing mesenchyme. As a key step toward laying the framework for identifying key molecular targets these data can be used for translational studies aimed at developing effective therapies for human palatal clefts.
Project description:The overall goal of this project is to investigate the role of TGF-beta signaling in palate development in order to discover candidate therapeutics for preventing and treating congenital birth defects. Here, we conducted gene expression profiling of embryonic palatal tissue from wild type mice as well as those with a neural crest specific conditional inactivation of the Tgfbr2 gene. The latter mice provide a model of cleft palate formation. To investigate the mechanism of cleft palate resulting from mutations in TGFBR2, we analyzed neural crest specific conditional inactivation of Tgfbr2 in mice (Tgfbr2fl/fl;Wnt1-Cre). We performed microarray analyses using the palatal tissue of Tgfbr2fl/fl;Wnt1-Cre mice at embryonic day E13.5 (prior to palatal fusion, n=6 per genotype) and E14.5 (during palatal fusion, n=5 per genotype) to examine the genes regulated by Tgf-beta during palate formation.
Project description:Proper retinoic acid (RA) signaling is essential for normal craniofacial development. Both excessive RA and RA deficiency in early embryonic stage led to a variety of craniofacial malformations, e.g., cleft palate, which have been investigated extensively. Dysregulated Wnt and Shh signaling were shown to underlie the pathogenesis of RA-induced craniofacial defects. In our present study, we showed a spatiotemporal-specific effect of RA signaling in regulating early development of facial prominences. While inhibited the Wnt activities in E12.5/E13.5 mouse palatal shelves, early exposure of excessive RA induced Wnt signaling and Wnt-related gene expression in mouse embryonic Frontonasal/Maxillary processes. A conserved regulatory network of miR-484-Fzd5 was identified to play critical roles in RA regulated craniofacial development using RNA-seq.
Project description:Proper retinoic acid (RA) signaling is essential for normal craniofacial development. Both excessive RA and RA deficiency in early embryonic stage led to a variety of craniofacial malformations, e.g., cleft palate, which have been investigated extensively. Dysregulated Wnt and Shh signaling were shown to underlie the pathogenesis of RA-induced craniofacial defects. In our present study, we showed a spatiotemporal-specific effect of RA signaling in regulating early development of facial prominences. While inhibited the Wnt activities in E12.5/E13.5 mouse palatal shelves, early exposure of excessive RA induced Wnt signaling and Wnt-related gene expression in mouse embryonic Frontonasal/Maxillary processes. A conserved regulatory network of miR-484-Fzd5 was identified to play critical roles in RA regulated craniofacial development using RNA-seq.