Comparative analysis of gene expression in TGF-ß3 mutant mice with cleft palate
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ABSTRACT: Comparison of global palatal transcriptomes between wild‐type (WT) and TGF‐β3 ‐/‐ homozygous (HM) mouse embryos at crucial palatogenesis stages, E14.5 when initial contact is reached between palatal shelves and E16.5 when palatal fusion in completed in mice using RNA sequencing technology (RNA-Seq). Our RNA-Seq data revealed that 4115 and 5304 genes were statistically deferentially (p < 0.05) expressed at E14.5 vs E16.5 in WT palates and HM palates, respectively. We then applied a 2.0-fold change cut-off to emphasize on significantly deferentially expressed genes. Genes that were uniquely up/down–regulated in either WT or HM at E16.5 vs E14.5 were identified and considered CP-related genes.
Project description:Background: In humans, cleft palate (CP) accounts for one of the largest number of birth defects with a complex genetic and environmental etiology. TGFM-NM-23 has been established as an important regulator of palatal fusion in mice and it has been shown that TGFM-NM-23-null mice exhibit CP without any other major deformities. However, the genes that regulate cellular decisions and molecular mechanisms maintained by the TGFM-NM-23 pathway throughout palatogenesis are predominantly unexplored. Our objective in this study was to analyze global transcriptome changes within the palate during different gestational ages within TGFM-NM-23 knockout mice to identify TGFM-NM-23-associated genes previously unknown to be associated with the development of cleft palate. We used deep sequencing technology, RNA-Seq, to analyze the transcriptome of TGFM-NM-23 knockout mice at crucial stages of palatogenesis, including palatal growth (E14.5), adhesion (E15.5), and fusion (E16.5). Results: The overall transcriptome analysis of TGFM-NM-23 wildtype mice (C57BL/6) reveals that almost 6000 genes were upregulated during the transition from E14.5 to E15.5 and more than 2000 were downregulated from E15.5 to E16.5. Using bioinformatics tools and databases, we identified the most comprehensive list of CP genes (n = 322) in which mutations cause CP either in humans or mice, and analyzed their expression patterns. The expression motifs of CP genes between TGFM-NM-23+/M-bM-^HM-^R and TGFM-NM-23M-bM-^HM-^R/M-bM-^HM-^R were not significantly different from each other, and the expression of the majority of CP genes remained unchanged from E14.5 to E16.5. Using these patterns, we identified 8 unique genes within TGFM-NM-23M-bM-^HM-^R/M-bM-^HM-^R mice (Chrng Foxc2, H19, Kcnj13, Lhx8, Meox2, Shh, and Six3), which may function as the primary contributors to the development of cleft palate in TGFM-NM-23M-bM-^HM-^R/M-bM-^HM-^R mice. When the significantly altered CP genes were overlaid with TGFM-NM-2 signaling, all of these genes followed the Smad-dependent pathway. Conclusions: Our study represents the first analysis of the palatal transcriptome of the mouse, as well as TGFM-NM-23 knockout mice, using deep sequencing methods. In this study, we characterized the critical regulation of palatal transcripts that may play key regulatory roles through crucial stages of palatal development. We identified potential causative CP genes in a TGFM-NM-23 knockout model, which may lead to a better understanding of the genetic mechanisms of palatogenesis and provide novel potential targets for gene therapy approaches to treat cleft palate. Palatal mRNA profiles of wild type (WT), TGFM-NM-23+/-, and TGFM-NM-23-/- mice at E14.5, E15.5, and E16.5 were generated by deep sequencing, in triplicate, using Illumina HiSeq2000
Project description: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: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:Background: In humans, cleft palate (CP) accounts for one of the largest number of birth defects with a complex genetic and environmental etiology. TGFβ3 has been established as an important regulator of palatal fusion in mice and it has been shown that TGFβ3-null mice exhibit CP without any other major deformities. However, the genes that regulate cellular decisions and molecular mechanisms maintained by the TGFβ3 pathway throughout palatogenesis are predominantly unexplored. Our objective in this study was to analyze global transcriptome changes within the palate during different gestational ages within TGFβ3 knockout mice to identify TGFβ3-associated genes previously unknown to be associated with the development of cleft palate. We used deep sequencing technology, RNA-Seq, to analyze the transcriptome of TGFβ3 knockout mice at crucial stages of palatogenesis, including palatal growth (E14.5), adhesion (E15.5), and fusion (E16.5). Results: The overall transcriptome analysis of TGFβ3 wildtype mice (C57BL/6) reveals that almost 6000 genes were upregulated during the transition from E14.5 to E15.5 and more than 2000 were downregulated from E15.5 to E16.5. Using bioinformatics tools and databases, we identified the most comprehensive list of CP genes (n = 322) in which mutations cause CP either in humans or mice, and analyzed their expression patterns. The expression motifs of CP genes between TGFβ3+/− and TGFβ3−/− were not significantly different from each other, and the expression of the majority of CP genes remained unchanged from E14.5 to E16.5. Using these patterns, we identified 8 unique genes within TGFβ3−/− mice (Chrng Foxc2, H19, Kcnj13, Lhx8, Meox2, Shh, and Six3), which may function as the primary contributors to the development of cleft palate in TGFβ3−/− mice. When the significantly altered CP genes were overlaid with TGFβ signaling, all of these genes followed the Smad-dependent pathway. Conclusions: Our study represents the first analysis of the palatal transcriptome of the mouse, as well as TGFβ3 knockout mice, using deep sequencing methods. In this study, we characterized the critical regulation of palatal transcripts that may play key regulatory roles through crucial stages of palatal development. We identified potential causative CP genes in a TGFβ3 knockout model, which may lead to a better understanding of the genetic mechanisms of palatogenesis and provide novel potential targets for gene therapy approaches to treat cleft palate.
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: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. RNA-seq analysis was done of palatal shelves dissected from E10.5, E11.5, E12.5, E13.5 and E14.5 mouse embryos.
Project description:The goal of this RNA-Sequencing experiment was to determine gene targets of Yap/Taz in the posterior palatal shelves prior to elevation at E14.5 in mouse.
Project description:The goal of this study was to identify immediate early transcriptional targets of ephrin-B1 forward signaling that are relevant to palatogenesis. The Ephs compose a family of receptor tyrosine kinase signaling molecules that can be activated by their cognate ligands, the ephrins. Despite the importance of Eph/ephrin signaling in a wide variety of developmental and cell biological processes, a potential downstream transcriptional response has not been explored. To understand the role of ephrin-B1 signaling in palatogenesis, we examined transcriptional response to ephrin-B1 in a primary mouse embryonic palatal shelf cell culture system. We find an immediate early signature of gene expression that reflects the activation of Erk/MAPK signaling by ephrin-B1 signaling in the palatal shelves.
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.