Expression data from Tbx1 knockout (KO) palatal shlelves
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ABSTRACT: Deletion of Tbx1, a member of the T-box transcription factor gene family, results in abnormal epithelial fusion between the palatal shelves and the mandible, which induces cleft palate by inhibiting elevation of the palatal shelves. We used microarrays to determine the downstream genes of Tbx1 during palatogenesis and identified distinct classes of dysregulated genes.
Project description:To assess the influence of Tbx1 on gene expression profile within the developing palate we performed a microarray screen using RNA isolated from dissected secondary palate shelves of E13.5 wild type, Tbx1+/- and Tbx1-/- mice. Significant differences were identified between genotypes, with a total of 67 genes demonstrating at least a 2-fold change (p<0.05) in expression. These were clustered into 5 groups, including those downregulated in mutant compared to wild type and heterozygote (n=36); those progressively downregulated from wild type to mutant (n=12); those upregulated in heterozygote and downregulated in mutant compared to wild type (n=2); those progressively upregulated from wild type to mutant (n=12) and those downregulated in heterozygote and upregulated in mutant compared to wild type (n=5). High-throughput real time quantitative RT-PCR confirmed a total of 18 genes significantly changed between wild type and mutant and 24 between heterozygote and mutant. Amongst these, 15 were present in both groups and all except 1 were downregulated in the mutant. There were no significant differences in gene expression between wild type and heterozygous palatal shelves. Secondary palatal shelf pairs were carefully microdissected from E13.5 Tbx1+/+; Tbx1+/- and Tbx1-/- embryos (3 embryos per genotype as biological replicates). RNA was extracted from each pooled shelf pair generating nine RNA samples in total, each one analysed using a single microarray.
Project description:We identify a role for two evolutionarily related, secreted metalloproteases of the ADAMTS family (A disintegrin-like and metalloprotease domain with thrombospondin type-1 motif), ADAMTS20 and ADAMTS9, in palatogenesis. Adamts20 mutations cause the mouse white spotting mutant belted (bt), whereas Adamts9 is essential for survival beyond 7.5 days of gestation (E7.5). Functional overlap of Adamts9 with Adamts20 was established in bt/bt:Adamts9+/- mice, which have increased white spotting relative to bt mice, as previously reported, and a fully penetrant cleft palate. Palatal closure was delayed, although eventually completed, in both bt/+;Adamts9+/- and bt/bt mice, demonstrating a cooperative role of these related genes. Adamts9 and Adamts20 are both expressed in palatal mesenchyme, with Adamts9 expressed exclusively in microvascular endothelial cells. Palatal shelves from bt/bt:Adamts9+/- mice fused in culture, suggesting an intact TGF signaling pathway in palatal epithelium, and indicating a temporally specific delay in palatal shelf elevation and growth toward the midline. Palatal shelf mesenchymal cells showed a statistically significant decrease of cell proliferation at E13.5 and E14.5, as well as decreased processing of versican, an ADAMTS substrate, at these stages. Vcan haploinsufficiency led to a greater penetrance of cleft palate in bt mice, and impaired proliferation was also seen in palatal mesenchymal cells of these mice, suggesting a role for ADAMTS-mediated versican proteolysis in palatal closure. In a parallel with recent work identifying a role for a bioactive ADAMTS-generated versican fragment in regulating apoptosis during interdigital web regression, we propose that versican proteolysis may influence palatal mesenchymal cell proliferation. Palatal shelves were dissected from four E13.75 Adamts9+/-:bt/bt embyos (correspond to the 4 samples: Palate_Adamts9+/-:bt/bt_Rep1, Palate_Adamts9+/-:bt/bt_Rep2, Palate_Adamts9+/-:bt/bt_Rep3 and Palate_Adamts9+/-:bt/bt_Rep4) and age-matched 3 wild-type C57Bl/6 embryos (correspond to the 3 samples: Palate_WT_Rep1, Palate_WT_Rep2, and Palate_WT_Rep3) that were used as the controls
Project description:The involvement of skeletal muscle in the process of palatal development in mammals is an example of Waddingtonian epigenetics. Our earlier study showed that the cleft palate develops in the complete absence of skeletal musculature during embryonic development in mice. This contrasts with previous beliefs that tongue obstruction prevents the elevation and fusion of the palatal shelves. We argue that the complete absence of mechanical stimuli from the adjacent muscle, i.e., the lack of both static and dynamic loading, results in disordered palatogenesis. We further suggest that proper fusion of the palatal shelves depends not only on mechanical but also on paracrine contributions from the muscle. The muscle's paracrine role in the process of palatal fusion is achieved through its being a source of certain secreted and/or circulatory proteins. A cDNA microarray analysis revealed differentially expressed genes in the cleft palate of amyogenic mouse fetuses and suggested candidate molecules with a novel function in palatogenesis (e.g., Tgfbr2, Bmp7, Trim71, E2f5, Ddx5, Gfap, Sema3f). In particular, we report on Gdf11 mutant mouse that has cleft palate, and on several genes whose distribution is normally restricted to the muscle (completely absent in our amyogenic mouse model), but which are found down-regulated in amyogenic mouse cleft palate. These molecules probably present a subset of paracrine cues that influence palatogenesis from the adjacent muscle. Future studies will elucidate the role of these genes in muscle-palate crosstalk, connecting the cues produced by the muscle with the cartilage and bone tissue's responses to these cues, through various degrees of cell proliferation, death, differentiation and tissue fusion.
Project description:To assess the influence of Tbx1 on gene expression profile within the developing palate we performed a microarray screen using RNA isolated from dissected secondary palate shelves of E13.5 wild type, Tbx1+/- and Tbx1-/- mice. Significant differences were identified between genotypes, with a total of 67 genes demonstrating at least a 2-fold change (p<0.05) in expression. These were clustered into 5 groups, including those downregulated in mutant compared to wild type and heterozygote (n=36); those progressively downregulated from wild type to mutant (n=12); those upregulated in heterozygote and downregulated in mutant compared to wild type (n=2); those progressively upregulated from wild type to mutant (n=12) and those downregulated in heterozygote and upregulated in mutant compared to wild type (n=5). High-throughput real time quantitative RT-PCR confirmed a total of 18 genes significantly changed between wild type and mutant and 24 between heterozygote and mutant. Amongst these, 15 were present in both groups and all except 1 were downregulated in the mutant. There were no significant differences in gene expression between wild type and heterozygous palatal shelves.
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:Mutations in the transcription factor p63 underlie of a series of human malformation syndromes which are defined by a combination of epidermal, limb and craniofacial abnormalities including cleft lip and palate. Transcription profiling was performed to determine the role of p63 in vivo mouse palatal shelves. Microarray analysis was done of palatal shelves dissected from E14.0 wild-type versus p63-null mouse embryos.
Project description:We identify a role for two evolutionarily related, secreted metalloproteases of the ADAMTS family (A disintegrin-like and metalloprotease domain with thrombospondin type-1 motif), ADAMTS20 and ADAMTS9, in palatogenesis. Adamts20 mutations cause the mouse white spotting mutant belted (bt), whereas Adamts9 is essential for survival beyond 7.5 days of gestation (E7.5). Functional overlap of Adamts9 with Adamts20 was established in bt/bt:Adamts9+/- mice, which have increased white spotting relative to bt mice, as previously reported, and a fully penetrant cleft palate. Palatal closure was delayed, although eventually completed, in both bt/+;Adamts9+/- and bt/bt mice, demonstrating a cooperative role of these related genes. Adamts9 and Adamts20 are both expressed in palatal mesenchyme, with Adamts9 expressed exclusively in microvascular endothelial cells. Palatal shelves from bt/bt:Adamts9+/- mice fused in culture, suggesting an intact TGFbeta signaling pathway in palatal epithelium, and indicating a temporally specific delay in palatal shelf elevation and growth toward the midline. Palatal shelf mesenchymal cells showed a statistically significant decrease of cell proliferation at E13.5 and E14.5, as well as decreased processing of versican, an ADAMTS substrate, at these stages. Vcan haploinsufficiency led to a greater penetrance of cleft palate in bt mice, and impaired proliferation was also seen in palatal mesenchymal cells of these mice, suggesting a role for ADAMTS-mediated versican proteolysis in palatal closure. In a parallel with recent work identifying a role for a bioactive ADAMTS-generated versican fragment in regulating apoptosis during interdigital web regression, we propose that versican proteolysis may influence palatal mesenchymal cell proliferation.
Project description:Follistatin antagonizes TGF-b3-induced epithelial-mesenchymal transition in vitro: Implications for murine palate development by microarray analysis<br><br>Cleft palate is among the most frequent human birth defects. A number of genes and encoded proteins have been shown to play a crucial role in the process of palatogenesis. The central role is attributed to the cytokine TGF-ß3 which is expressed in the medial edge epithelium, (MEE), covering the growing palatal shelves already prior to the fusion process. Gene targeted mice with a palatal cleft phenotype may be divided into factors acting upstream of TGFß-3 in regulating its gene expression or downstream in its signal transduction pathway. The fusion process itself gets explained either by a transition of the epithelial cells into mesenchymal cells (EMT.) or by programmed cell death (apoptosis) of the epithelial cells. No explanation could ever been given why the TGF-ß3 producing epithelial cells do not undergo differentiation or apoptosis prior to the contact of the two shelves. We screened the MEE for expression of known antagonists of TGFß-molecules and detected the gene coding for follistatin to be coexpressed with TGF-ß3. We can show that follistatin directly binds to TGFß3 and that it completely blocks TGF-ß3 induced EMT of an epithelial cell line in vitro. EMT of the cells was analyzed by microarray hybridization.
Project description:Velo-cardio-facial syndrome/DiGeorge syndrome/22q11.2 deletion syndrome (22q11DS) patients have a submucous cleft palate, velo-pharyngeal insufficiency associated with hypernasal speech, facial muscle hypotonia and feeding difficulties. Inactivation of both alleles of mouse Tbx1, encoding a T-box transcription factor, deleted on 22q11.2, results in a cleft palate and a reduction or loss of branchiomeric muscles. To identify genes downstream of Tbx1 for myogenesis, gene profiling was performed on mandibular arches (MdPA1) from Tbx1+/+ and Tbx1-/- mouse embryos.
Project description:Velo-cardio-facial syndrome/DiGeorge syndrome/22q11.2 deletion syndrome (22q11DS) patients have a submucous cleft palate, velo-pharyngeal insufficiency associated with hypernasal speech, facial muscle hypotonia and feeding difficulties. Inactivation of both alleles of mouse Tbx1, encoding a T-box transcription factor, deleted on 22q11.2, results in a cleft palate and a reduction or loss of branchiomeric muscles. To identify genes downstream of Tbx1 for myogenesis, gene profiling was performed on mandibular arches (MdPA1) from Tbx1+/+ and Tbx1-/- mouse embryos.