Project description:We report on seven novel patients with a submicroscopic 22q12 deletion. The common phenotype constitutes a contiguous gene deletion syndrome on chromosome 22q12.1q12.2, featuring NF2-related schwannoma of the vestibular nerve, corpus callosum agenesis and palatal defects. Combining our results with the literature, eight patients are recorded with palatal defects in association with haploinsufficiency of 22q12.1, including the MN1 gene. These observations, together with the mouse expression data and the finding of craniofacial malformations including cleft palate in a Mn1-knockout mouse model, suggest that this gene is a candidate gene for cleft palate in humans.
Project description:WIZ (Widely Interspaced Zinc Finger) is associated with the G9a-GLP protein complex, a key H3K9 methyltransferase suggesting a role in transcriptional repression. However, its role in embryonic development is poorly described. In order to assess the loss of function of WIZ, we generated CRISPR/Cas9 WIZ knockout mouse model with 32 nucleotide deletion. Observing the lethality status, we identified the WIZ knockouts to be subviable during embryonic development and non-viable after birth. Morphology of developing embryo was analyzed at E14.5 and E18.5 and our findings were supported by microCT scans. Wiz KO showed improper development in multiple aspects, specifically in the craniofacial area. In particular, shorter snout, cleft palate, and cleft eyelids were present in mutant embryos. Palatal shelves were hypomorphic and though elevated to a horizontal position on top of the tongue, they failed to make contact and fuse. By comparison of proliferation pattern and histone methylation in developing palatal shelves we brought new evidence of importance WIZ dependent G9a-GLP methylation complex in craniofacial development, especially in palate shelf fusion.
Project description:Development of the secondary palate in mammals is a complex process that can be easily perturbed, leading to the common and distressing birth defect cleft palate. Animal models are particularly useful tools for dissecting underlying genetic components of cleft palate. We describe a new cleft palate model resulting from a transgene insertion mutation. Transgene insertional mutagenesis disrupts the genomic organization and expression of the Ap2?1 gene located on chromosome 11. This gene encodes the ?2-adaptin subunit of the heterotetrameric adaptor protein 2 complex involved in clathrin-dependent endocytosis. Homozygous cleft palate mutant mice express no Ap2?1 messenger RNA or ?2-adaptin protein and die during the perinatal period. Heterozygous mice are phenotypically normal despite expressing diminished ?2-adaptin messenger RNA and protein compared with wildtype. Remarkably, the paralogous ?1-adaptin subunit of the adaptor protein 1 complex partially substitutes for the missing ?2-adaptin in embryonic fibroblasts from homozygous mutant mice, resulting in assembly of reduced levels of an adaptor protein 2 complex bearing ?1-adaptin. This variant adaptor protein 2 complex is, therefore, apparently capable of maintaining viability of the homozygous mutant embryos until birth but insufficient to support palatogenesis. Nonsyndromic cleft palate in an animal model is associated with disruption of the Ap2?1 gene.
Project description:Cleft palate is among the most common human birth defects. Submucous cleft palate (SMCP) is a subgroup of cleft palate, which may be as common as overt cleft palate. Despite the high frequency of SMCP in humans, only recently have several animal models of SMCP begun to provide insight into the mechanisms by which SMCP develops. In this study, we show that enhanced BMP signaling through constitutively active ACVR1 in palatal epithelium causes submucous cleft palate in mice. In these mutant mice, the fusion of both palatal mesenchyme in hard palate, and muscles in soft palate were hampered by epithelial tissue. During palatal fusion, enhanced SMAD-dependent BMP signaling impaired cell death and altered cell proliferation rate in medial edge epithelium (MEE), and resulted in MEE persistence. At the molecular level, downregulation of ?Np63, which is crucial for normal palatal fusion, in MEE cells was impaired, leading to a reduction in caspase-3 activation. Our study provides a new insight into the etiology of SMCP caused by augmented BMP signaling.
Project description:In mammals, embryonic development are highly regulated morphogenetic processes that are tightly controlled by genetic elements. Failure of any one of these processes can result in embryonic malformation. The lysyl oxidase (LOX) family genes are closely related to human diseases. In this study, we investigated the essential role of lysyl oxidase-like 3 (LOXL3), a member of the LOX family, in embryonic development. Mice lacking LOXL3 exhibited perinatal lethality, and the deletion of the Loxl3 gene led to impaired development of the palate shelves, abnormalities in the cartilage primordia of the thoracic vertebrae and mild alveolar shrinkage. We found that the obvious decrease of collagen cross-links in palate and spine that was induced by the lack of LOXL3 resulted in cleft palate and spinal deformity. Thus, we provide critical in vivo evidence that LOXL3 is indispensable for mouse palatogenesis and vertebral column development. The Loxl3 gene may be a candidate disease gene resulting in cleft palate and spinal deformity.
Project description:IntroductionThis study aimed to investigate the mutation of T-box transcription factor TBX22 exon 5 in children with non-syndromic cleft palate. Four mutations in TBX22 exon 5 in X-linked cleft palate with ankyloglossia (CPX) patients had been identified in the previous studies. The study used the syndromic cleft palate susceptibility gene as a candidate gene for more common non-syndromic cleft palate.Material and methodsA family-based study with parents and their children composing parent-child trios was performed in this research. Twenty children with non-syndromic cleft palate and 38 healthy parents were enrolled. TBX22 exon 5 was examined by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing. The peaks of the sequence diagrams were analyzed using chromas221 and the results of sequencing were proofread using dnastar6.13. The index of the transmission disequilibrium test (TDT) was calculated through McNemar testing.ResultsWe have not found the presence of any mutation of TBX22 exon 5 reported in syndromic cleft palate patients in references. The index of TDT was 0.56 and showed no statistically significant difference (p<0.05). No TBX22 exon 5 mutation was found in the 20 children.ConclusionsMutation of TBX22 exon 5 is not associated with non-syndromic cleft palate in the population of Jiangzhe areas in China.
Project description:Cleft palate is a common birth defect in humans and is a common phenotype associated with syndromic mutations in fibroblast growth factor receptor 2 (Fgfr2). Cleft palate occurred in nearly all mice homozygous for the Crouzon syndrome mutation C342Y in the mesenchymal splice form of Fgfr2. Mutant embryos showed delayed palate elevation, stage-specific biphasic changes in palate mesenchymal proliferation, and reduced levels of mesenchymal glycosaminoglycans (GAGs). Reduced levels of feedback regulators of FGF signaling suggest that this gain-of-function mutation in FGFR2 ultimately resembles loss of FGF function in palate mesenchyme. Knowledge of how mesenchymal FGF signaling regulates palatal shelf development may ultimately lead to pharmacological approaches to reduce cleft palate incidence in genetically predisposed humans.
Project description:Cleft palate is one of the most common craniofacial birth defects, however, little is known about how changes in the DNA damage response (DDR) cause cleft palate. To determine the role of DDR during palatogenesis, the DDR process was altered using a pharmacological intervention approach. A compromised DDR caused by a poly (ADP-ribose) polymerase (PARP) enzyme inhibitor resulted in cleft palate in wild-type mouse embryos, with increased DNA damage and apoptosis. In addition, a mouse genetic approach was employed to disrupt breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2), known as key players in DDR. An ectomesenchymal-specific deletion of Brca1 or Brca2 resulted in cleft palate due to attenuation of cell survival. This was supported by the phenotypes of the ectomesenchymal-specific Brca1/Brca2 double-knockout mice. The cleft palate phenotype was rescued by superimposing p53 null alleles, demonstrating that the BRCA1/2-p53 DDR pathway is critical for palatogenesis. Our study highlights the importance of DDR in palatogenesis.
Project description:In contrast to the progress that has been made toward understanding the genetic etiology of cleft lip with or without cleft palate, relatively little is known about the genetic etiology for cleft palate only (CPO). A common coding variant of grainyhead like transcription factor 3 ( GRHL3) was recently shown to be associated with risk for CPO in Europeans. Mutations in this gene were also reported in families with Van der Woude syndrome. To identify rare mutations in GRHL3 that might explain the missing heritability for CPO, we sequenced GRHL3 in cases of CPO from Africa. We recruited participants from Ghana, Ethiopia, and Nigeria. This cohort included case-parent trios, cases and other family members, as well as controls. We sequenced exons of this gene in DNA from a total of 134 nonsyndromic cases. When possible, we sequenced them in parents to identify de novo mutations. Five novel mutations were identified: 2 missense (c.497C>A; p.Pro166His and c.1229A>G; p.Asp410Gly), 1 splice site (c.1282A>C p.Ser428Arg), 1 frameshift (c.470delC; p.Gly158Alafster55), and 1 nonsense (c.1677C>A; p.Tyr559Ter). These mutations were absent from 270 sequenced controls and from all public exome and whole genome databases, including the 1000 Genomes database (which includes data from Africa). However, 4 of the 5 mutations were present in unaffected mothers, indicating that their penetrance is incomplete. Interestingly, 1 mutation damaged a predicted sumoylation site, and another disrupted a predicted CK1 phosphorylation site. Overexpression assays in zebrafish and reporter assays in vitro indicated that 4 variants were functionally null or hypomorphic, while 1 was dominant negative. This study provides evidence that, as in Caucasian populations, mutations in GRHL3 contribute to the risk of nonsyndromic CPO in the African population.
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.