Project description:We used single-cell RNA sequencing (scRNA-seq) to profile Wnt signaling genes in maxillary and mandibular tooth organs from E15.5 and P1 stages
Project description:Purpose: the goals of this study are to explore the effect of loss of Ptip in Sp7 positive dental progenitor cells on CD45- Ter119- Tie2- dental progenitor cells Methods: CD45- Ter119- Tie2- dental progenitor cells were sorted by FACs in lower incisors from Ptipf/f and Ptipf/f;Sp7-cre mice and performed RNAseq Our finding reveals that Ptip as crucial regulator in tooth homeostasis, functioning to safeguard the Sp7+ progenitor cells epigenome from a breach in lineage confinement that triggers irreversible tooth defects. Conclusions: loss of Ptip unregulate dental development and active Wnt signal pathway
Project description:Mutations in MSX1 cause craniofacial developmental defects, including tooth agenesis, in humans and mice. Previous studies suggest that Msx1 activates Bmp4 expression in the developing tooth mesenchyme to drive early tooth organogenesis. Whereas Msx1−/− mice exhibit developmental arrest of all tooth germs at the bud stage, however, mice with neural crest-specific inactivation of Bmp4 (Bmp4ncko/ncko), which lack Bmp4 expression in the developing tooth mesenchyme, showed developmental arrest of only mandibular molars. We recently demonstrated that deletion of Osr2, which encodes a zinc finger transcription factor expressed in a lingual-to-buccal gradient in the developing tooth bud mesenchyme, rescued molar tooth morphogenesis in both Msx1−/− and Bmp4ncko/ncko mice. In this study, through RNA-seq analyses of the developing tooth mesenchyme in mutant and wildtype embryos, we found that Msx1 and Osr2 have opposite effects on expression of several secreted Wnt antagonists in the tooth bud mesenchyme. Remarkably, both Dkk2 and Sfrp2 exhibit Osr2-dependent preferential expression on the lingual side of the tooth bud mesenchyme and expression of both genes was up-regulated and expanded into the tooth bud mesenchyme in Msx1−/− and Bmp4ncko/ncko mutant embryos. We show that pharmacological activation of canonical Wnt signaling by either lithium chloride (LiCl) treatment or by inhibition of Dkk in utero was sufficient to rescue mandibular molar tooth morphogenesis in Bmp4ncko/ncko mice. Furthermore, whereas inhibition of Dkk alone was insufficient to rescue tooth morphogenesis in Msx1−/− mice, pharmacological inhibition of Dkk in combination with genetic inactivation of Sfrp2 and Sfrp3 rescued maxillary molar morphogenesis in Msx1−/− mice. Together, these data reveal a novel mechanism that the Bmp4-Msx1 pathway drives tooth organogenesis by activating Wnt signaling via regulation of the secreted Wnt antagonists.
Project description:Mutations in MSX1 cause craniofacial developmental defects, including tooth agenesis, in humans and mice. Previous studies suggest that Msx1 activates Bmp4 expression in the developing tooth mesenchyme to drive early tooth organogenesis. Whereas Msx1−/− mice exhibit developmental arrest of all tooth germs at the bud stage, however, mice with neural crest-specific inactivation of Bmp4 (Bmp4ncko/ncko), which lack Bmp4 expression in the developing tooth mesenchyme, showed developmental arrest of only mandibular molars. We recently demonstrated that deletion of Osr2, which encodes a zinc finger transcription factor expressed in a lingual-to-buccal gradient in the developing tooth bud mesenchyme, rescued molar tooth morphogenesis in both Msx1−/− and Bmp4ncko/ncko mice. In this study, through RNA-seq analyses of the developing tooth mesenchyme in mutant and wildtype embryos, we found that Msx1 and Osr2 have opposite effects on expression of several secreted Wnt antagonists in the tooth bud mesenchyme. Remarkably, both Dkk2 and Sfrp2 exhibit Osr2-dependent preferential expression on the lingual side of the tooth bud mesenchyme and expression of both genes was up-regulated and expanded into the tooth bud mesenchyme in Msx1−/− and Bmp4ncko/ncko mutant embryos. We show that pharmacological activation of canonical Wnt signaling by either lithium chloride (LiCl) treatment or by inhibition of Dkk in utero was sufficient to rescue mandibular molar tooth morphogenesis in Bmp4ncko/ncko mice. Furthermore, whereas inhibition of Dkk alone was insufficient to rescue tooth morphogenesis in Msx1−/− mice, pharmacological inhibition of Dkk in combination with genetic inactivation of Sfrp2 and Sfrp3 rescued maxillary molar morphogenesis in Msx1−/− mice. Together, these data reveal a novel mechanism that the Bmp4-Msx1 pathway drives tooth organogenesis by activating Wnt signaling via regulation of the secreted Wnt antagonists.
Project description:Odontomas are classified as odontogenic benign tumors, which show disorganized dental mineralized hard tissue formation in the jaw, but mechanisms in the induction of odontomas remain to be clarified. Odontomas are also thought to be developmental anomalies of tooth germ, which frequently occur in patients with familial adenomatous polyposis (FAP) involving activation of Wnt/b-catenin signaling. However, the roles of Wnt/b-catenin signaling in odontomas or odontogenic cells remain to be clarified. The current study was conducted to investigate the expression of b-catenin in odontomas and the function of Wnt/b-catenin signaling in odontogenic epithelial cells and tooth germ development. b-catenin frequently accumulated in the nucleus and/or cellular cytoplasm of remaining odontogenic epithelial cells in human odontoma specimens, immunohistochemically. Activation of Wnt/b-catenin signaling inhibited odontogenic epithelial cell proliferation and mouse tooth germ development, while inducing epithelial bud formation in the novel developed epithelial tooth bud culture system derived from mouse tooth germ. We identified Semaphorin 3A (Sema3A) as a downstream molecule of Wnt/b-catenin signaling using DNA microarray analysis and showed that Wnt/b-catenin signaling-dependent reduction of Sema3A expression resulted in suppression of odontogenic epithelial cell proliferation. Novel developed epithelial tooth bud culture system revealed that Sema3A expression is required in epithelial budding morphogenesis. These results suggest that Wnt/b-catenin signaling negatively regulates odontogenic epithelial cell proliferation and tooth germ development through decreased-Sema3A expression, and aberrant activation of Wnt/b-catenin signaling may be associated with the formation of odontomas.
Project description:Previous studies have suggested that Bmp4 is a key Msx1-dependent mesenchymal odontogenic signal for driving tooth morphogenesis through the bud-to-cap transition. Whereas the bud stage tooth developmental arrest in Msx1-/- mutant mice was accompanied by reduction in mesenchymal Bmp4 mRNA expression, we show that depleting functional Bmp4 mRNAs in the tooth mesenchyme, through neural crest-specific gene inactivation in Bmp4f/f;Wnt1Cre mice, caused mandibular molar developmental arrest at the bud stage but allowed maxillary molars and incisors to develop to mineralized teeth. We show that the Wnt inhibitors Dkk2 and Wif1 were much more abundantly expressed in the mandibular than maxillary molar mesenchyme in wildtype embryos and that Dkk2 expression was significantly unregulated in the tooth mesenchyme in Bmp4f/f;Wnt1Cre embryos. In addition, expression of Osr2, which encodes a zinc finger protein that antagonizes Msx1-mediated activation of odontogenic mesenchyme, is significantly upregulated in the molar mesenchyme in Bmp4f/f;Wnt1Cre embryos. Msx1 heterozygosity enhanced maxillary molar developmental defects whereas Osr2 heterozygosity rescued mandibular first molar morphogenesis in Bmp4f/f;Wnt1Cre mice. Moreover, in contrast to complete lack of supernumerary tooth initiation in Msx1-/-Osr2-/- mutant mice, Osr2-/-Bmp4f/f;Wnt1Cre compound mutant mice exhibit formation and subsequent arrest of supernumerary tooth germs that correlated with down regulation of Msx1 expression in the tooth mesenchyme. Taken together, our data indicate that, while reduction in mesenchymal Bmp4 expression alone could not account for the tooth bud arrest phenotype in Msx1-/- mutant mice, Bmp4 signaling synergizes with Msx1 and antagonizes Osr2 to activate mesenchymal odontogenic activity to drive tooth morphogenesis and sequential tooth formation. E13.5 mouse embryos tooth germs were microdissected by laser capture microdissection (LCM), and the mandibular molar and maxillary molar were separated. 3 pairs of control and mutant samples were pooled for the RNA extraction.
Project description:Previous studies have suggested that Bmp4 is a key Msx1-dependent mesenchymal odontogenic signal for driving tooth morphogenesis through the bud-to-cap transition. Whereas the bud stage tooth developmental arrest in Msx1-/- mutant mice was accompanied by reduction in mesenchymal Bmp4 mRNA expression, we show that depleting functional Bmp4 mRNAs in the tooth mesenchyme, through neural crest-specific gene inactivation in Bmp4f/f;Wnt1Cre mice, caused mandibular molar developmental arrest at the bud stage but allowed maxillary molars and incisors to develop to mineralized teeth. We show that the Wnt inhibitors Dkk2 and Wif1 were much more abundantly expressed in the mandibular than maxillary molar mesenchyme in wildtype embryos and that Dkk2 expression was significantly unregulated in the tooth mesenchyme in Bmp4f/f;Wnt1Cre embryos. In addition, expression of Osr2, which encodes a zinc finger protein that antagonizes Msx1-mediated activation of odontogenic mesenchyme, is significantly upregulated in the molar mesenchyme in Bmp4f/f;Wnt1Cre embryos. Msx1 heterozygosity enhanced maxillary molar developmental defects whereas Osr2 heterozygosity rescued mandibular first molar morphogenesis in Bmp4f/f;Wnt1Cre mice. Moreover, in contrast to complete lack of supernumerary tooth initiation in Msx1-/-Osr2-/- mutant mice, Osr2-/-Bmp4f/f;Wnt1Cre compound mutant mice exhibit formation and subsequent arrest of supernumerary tooth germs that correlated with down regulation of Msx1 expression in the tooth mesenchyme. Taken together, our data indicate that, while reduction in mesenchymal Bmp4 expression alone could not account for the tooth bud arrest phenotype in Msx1-/- mutant mice, Bmp4 signaling synergizes with Msx1 and antagonizes Osr2 to activate mesenchymal odontogenic activity to drive tooth morphogenesis and sequential tooth formation.
Project description:Primary objectives: Phase Ib: To estimate the MTD(s) and/or RP2D(s) of the triple combination of WNT974, LGX818 and cetuximab in patients with BRAFV600-mutant CRC harboring upstream Wnt pathway mutations.
Phase II: To estimate the preliminary anti-tumor activity of the RP2D(s) of WNT974 in combination with LGX818 and cetuximab in patients with BRAFV600-mutant CRC harboring upstream Wnt pathway mutations
Note:
Further enrollment to the study has been discontinued as of 21 March 2016. Therefore, references to phase II study design and objectives are no longer relevant.
Primary endpoints: 1. Phase Ib: To estimate the MTD(s)/RP2D(s) of the triple combination of WNT974, LGX818 and cetuximab in patients with BRAFV600-mutant, KRAS wild-type (WT) mCRC harboring upstream Wnt pathway mutations, as measured by incidence of dose-limiting toxicities (DLTs) and exposure to WNT974 and LGX818 as measured by PK parameters.
2. Phase II: To estimate the preliminary anti-tumor activity at the RP2D(s) of the combination of WNT974, LGX818 and cetuximab, in patients with BRAFV600-mutant metastatic colorectal cancer harboring upstream Wnt pathway mutations, based on the Overall Response Rate (ORR).
Note: Further enrollment to the study has been discontinued as of 21 March 2016. Therefore, references to phase II study design and objectives are no longer relevant.