ABSTRACT: We generated a genome-wide map of candidate enhancers from the maxillary arch (primordium for the upper jaw) of mouse embryos Examination of histone modification H3K27ac (distinguishes active enhancers from inactive enhancer elements) in the maxillary arch tissue
Project description:We used laser capture microdissection to isolate maxillary arch mesenchyme from E10.5 embryos. This tissue was collected from both control (3x) and Lhx6-/-;Lhx8-/- mutant (3x) samples. Transcriptional profiling was performed using Affymetrix GeneChip Mouse Genome 430 2.0 arrays. The mutant mice are of mixed genetic background of C57BL/6J, 129 and CD-1 strains. The head of E10.5 embryos was collected and embedded in Optimal Cutting Temperature resin (Tissue-Tek) by flash freezing on dry ice. The frozen sections were collected on polyethylene naphthalate membrane slides (Leica). Leica LMD6000 Laser Micro-Dissection System was used to cut out the normal expression domain of Lhx6 and Lhx8 in the maxillary arch mesenchyme. The tissue was collected from the entire antero-posterior extent of the maxillary arches. Total RNA was extracted using RNeasy Micro Kit (Qiagen). Subsequent steps of transcriptional profiling were performed by the New York University Genome Technology Center, beginning with the amplification of RNA by Ovation Nano Amplification system (NuGen). RNA samples from three wild-type and three Lhx6−/−;Lhx8−/− mutant embryos, all somite count- and sex-matched (females), were analyzed with Affymetrix GeneChip Mouse Genome 430 2.0 arrays. A list of Lhx-regulated genes were generated from the microarray result based on the following criteria: fold change in the average expression between wild types and Lhx6−/−;Lhx8−/− mutants is >1.5, the difference is statistically significant (P < 0.05) and the average intensity of the probe signal is >100 for wild-type and/or mutant samples. The resulting list of 212 genes was used for a gene ontology analysis with DAVID (27,28).
Project description:The patterning of the facial midline involves early specification of neural crest cells to form skeletal tissues that support the upper jaw . In order to understand the molecular mechanisms involved we have taken advantage of a beak duplication model developed in the chicken embryo. Here we can induce the transformation of the side of the beak into a second midline that is easily identifiable by the formation of a supernumerary egg tooth. The phenotype is induced by implanting two microscopic beads, one soaked in retinoic acid and the other soaked in Noggin into the side of the head of the chicken embryo. Here we use microarrays to profile expression of maxillary mesenchyme 16h after placing the beads. A subset of genes were validated using in situ hybridization and QPCR. The aims of the study are to test the function of these genes using retroviral transgenesis, knockdown with morpholinos or expression of secreted proteins and their application to the embryo. Embryos were incubated at 38 degrees C until they reached Hamburger Hamilton Stage 15 or 25 somites. Four different treatments were carried out consisting of two beads simultaneously implanted into the side of the head between the eye and mandibular arch. The beads were either Noggin+retinoic acid, Tris+retinoic acid, Noggin+DMSO or the control, Tris+DMSO. Embryos were reincubated for another 16h until they reached stage 18. Embryos were dissected on ice in Hanks Buffered Salt Solution and batches of 12-15 maxillary pieces were snap frozen in liquid Nitrogen. These pooled facial prominences comprised one biological replicate. A total of three biological replicates were generated for each treatment.
Project description:We performed chromatin immunoprecipitation (ChIP) followed by high-throughput sequencing (seq) from mouse E11.5 maxillary arches using anti-LHX6 antibody to identify LHX target cis-regulatory elements. Overall design: Genome binding/occupancy profiling by high throughput sequencing using only wild-type E11.5 maxillary arch tissue.
Project description:Chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII; NR2F2) is an orphan nuclear receptor involved in cell-fate specification, organogenesis, angiogenesis and metabolism. Ablation of COUP-TFII in the mouse uterus causes infertility due to defects in embryo attachment and impaired uterine stromal cell decidualization. Although the function of COUP-TFII in uterine decidualization has been described in mice, its role in the human uterus remains unknown. To better elucidate the mechanisms with which COUP-TFII regulates target gene transcription, genome-wide COUP-TFII binding sites in human endometrial stromal cells (HESC) treated with deciduogenic hormones were identified using ChIP-seq. A total of 16,298 intervals (binding regions) for COUP-TFII were identified compared with the input in HESC chromatin with a very low false discovery rate (0.17%) using a stringent cutoff of p =1x10-10. Distribution of intervals showed that more than half (58.6%) of the COUP-TFII binding sites are located within 10 kb of gene boundaries. 7.5% of total intervals reside within the 10 kb promoter region. A total of 6,077 unique genes were identified to have COUP-TFII binding sites within 10 kb of their gene boundaries. Examination of NR2F2 binding in pooled primary human endometrial stromal cells from 6 healthy women upon decidualization with a hormone cocktail of cAMP, E2 and medroxyprogesterone acetate.
Project description:Embryonic cardiomyocytes possess the plasticity to choose between atrial and ventricular fates. For a limited window of time, the transcription factor COUP-TFII (Nr2f2) sufficiently and essentially confers the atrial identity through direct and indirect regulation of nearly half of chamber specific genes. Examination of COUP-TFII binding sites in embryonic artia
Project description:One of the key questions in developmental biology is how from universally shared molecular mechanisms and pathways, is it possible to generate organs displaying similar or complementary functions, with a wide range of different shapes or tissue organization? The dentition represents a valuable system to address the issues of differential molecular signatures generating specific tooth types. We performed a comparative transcriptomic analysis of developing murine lower incisors, mandibular molars and maxillary molars at the developmental cap stage (E14.5) prior to recognizable tooth shape and cusp pattern. We compared gene expression profiles in developing murine lower incisor and molars, as well as between the lower and upper (mandibular and maxillary) first molars
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:Naïve mouse embryonic stem cells (mESCs) and primed epiblast stem cells (mEpiSCs) represent successive snapshots of pluripotency during embryogenesis. Using transcriptomic and epigenomic mapping, we show that a small fraction of transcripts are differentially expressed between mESCs and mEpiSCs and these genes show expected changes in chromatin at their promoters and enhancers. Unexpectedly, the cis-regulatory circuitry of genes that are expressed at identical levels between these cell states also differs dramatically. In mESCs, these genes are associated with dominant proximal enhancers and dormant distal enhancers, which we term seed enhancers. In mEpiSCs, the naïve-dominant enhancers are lost, and the seed enhancers take up primary transcriptional control. Seed enhancers have increased sequence conservation and show preferential usage in downstream somatic tissues, often expanding into super enhancers. We propose that seed enhancers ensure proper enhancer utilization and transcriptional fidelity as mammalian cells transition from naïve pluripotency to a somatic regulatory program. ChIP sequencing of histone modifications in mouse epiblast stem cells
Project description:Growth and patterning of the face relies on several small buds of tissue, the facial prominences, which surround the primitive mouth. Beginning around E10 of mouse development the prominences undergo rapid growth and morphogenesis. By E11.5 the medial nasal prominences are in close apposition in the midline, as are the maxillary and medial nasal prominences on either side of the developing face. Subsequently, by E12.5 the nasal and maxillary prominences fuse to form a continuous shelf at the front of the face - the primary palate. Individual prominences are associated with specific developmental processes, and this is reflected by patterns of differential gene expression that give the prominences their unique identities. Thus, only the mandibular and maxillary prominences give rise to dentition while the frontonasal prominence has a unique role in olfaction, and the mandibular prominence in taste. We used microarrays to detail the differential gene expression program in each of the mandibular, maxillary, and frontonasal prominences during the key developmental timepoints of E10.0 through E12.5. Experiment Overall Design: Analysis of gene expression during growth and fusion of the facial prominences in the C57BL/6J mouse strain between embryonic (E) day 10.0 and 12.5. At the earliest timepoint, E10, only the mandibular prominence is a distinct entity that can be readily identified and dissected. The frontonasal prominence and the maxillary prominence are very small and not discrete from other components of the head such as the forebrain until E10.5. Analysis of these tissues at earlier timepoints would require laser capture and preamplification steps - techniques that were not used for the later timepoints. Thus samples were isolated from the mandibular prominence at E10.0 and from the mandibular, maxillary and frontonasal prominences of mouse embryos from E10.5 to E12.5, at 0.5 day intervals. In order to obtain sufficient sample for hybridization, each sample represents a pool of between 3 and 48 embryos depending on the timepoint. Specifically, the number of embryos were 40-48 for E10.0 (mandibular prominence only), 24-8 for E10.5, 8-9 for E11.0 and E11.5 and 3-4 for E12.0 and E12.5. Seven replicate samples were taken for each of the later five timepoints in each of the three prominences, with an additional seven samples for the mandibular E10.0 timepoint, for a total of 112 samples.