Project description:Foregut organogenesis is regulated by inductive interactions between the endoderm and the adjacent mesoderm. We identified genes induced in the foregut progenitors by the adjacent mesoderm. We used microarrays to detail the global programme of early foregut endoderm gene expression resulting from mesoderm induction and identified distinct classes of up-regulated genes during this process. Xenopus foregut endoderm explants cultured from Stages 15 to 23 either intact with mesoderm or as endoderm alone. Total RNA was isolated from the endoderm of these two culture conditions in quadruplicate and were subjected to Affymetrix microarray analysis.
Project description:Foregut organogenesis is regulated by inductive interactions between the endoderm and the adjacent mesoderm. We identified genes induced in the foregut progenitors by the adjacent mesoderm. We used microarrays to detail the global programme of early foregut endoderm gene expression resulting from mesoderm induction and identified distinct classes of up-regulated genes during this process.
Project description:We screened for differentially expressed genes in the developing notochord using the Affymetrix microarray system in Xenopus laevis. At late gastrula, we dissected four regions from the embryo, anterior mesoderm, posterior mesoderm, notochord and presomitic mesoderm. Three types of comparison were carried out to generate a list of predominantly notochord expressed genes: (1) Posterior mesoderm vs. anterior mesoderm; notochord genes are expected to be increased since the notochord is located in the posterior mesoderm. (2) Posterior mesoderm vs. whole embryos; notochord genes are expected to be increased. (3) Notochord vs. somite. This comparison sub-divided the group of posterior mesodermal genes identified in (1) and (2). All tissues are dissected using tungsten needles. We first dissected dorsal tissue above the archenteron from late gastrula to early neurula. To loosen tissue, we treated the dissected dorsal explant in a 1% cysteine solution (pH 7.4) and removed the neuroectodermal layer. Anterior mesoderm was dissected corresponding to about the anterior one-third of the archenteron roof, and the rest was collected as posterior mesoderm. The posterior mesodermal explant was dissected into notochord and somites, following a clearly visible border between the two tissues. The accuracy of all dissection was confirmed by RT-PCR of marker genes.
Project description:Digestive system development is orchestrated by combinatorial signaling interactions between endoderm and mesoderm, but how they are integrated in the genome is poorly understood. Here we identified the Xenopus foregut and hindgut progenitor transcriptomes, which are largely conserved with mammals. Using RNA-seq and ChIP-seq we show that BMP/Smad1 regulates dorsal-ventral gene expression in both the endoderm and mesoderm, whereas Wnt/b-catenin acts as a genome-wide toggle between foregut and hindgut programs. In addition to b-catenin-Tcf promoting hindgut gene transcription, we unexpectedly observed Wnt-repressed foregut genes associated with b-catenin-binding to DNA lacking Tcf motifs, suggesting a novel direct repression. We define how BMP and Wnt signaling are integrated in the genome with Smad1 and β-catenin co-occupying DNA elements associated with hundreds of key regulatory genes. These results extend our understanding of GI organogenesis and how Wnt and BMP may coordinate genomic responses in other contexts.
Project description:The purpose of this study is to examine transciptome dynamics at high resolution to 4 separate lineages. Here we provide snapshots of the Xenopus laevis transcriptome at Nieuwkoop and Faber stages 9., 10, 10.5, 11, 12 and 13 for the epidmeral, neural, ventral mesoderm and endoderm lineage
Project description:Digestive system development is orchestrated by combinatorial signaling interactions between endoderm and mesoderm, but how they are integrated in the genome is poorly understood. Here we identified the Xenopus foregut and hindgut progenitor transcriptomes, which are largely conserved with mammals. Using RNA-seq and ChIP-seq we show that BMP/Smad1 regulates dorsal-ventral gene expression in both the endoderm and mesoderm, whereas Wnt/b-catenin acts as a genome-wide toggle between foregut and hindgut programs. In addition to b-catenin-Tcf promoting hindgut gene transcription, we unexpectedly observed Wnt-repressed foregut genes associated with b-catenin-binding to DNA lacking Tcf motifs, suggesting a novel direct repression. We define how BMP and Wnt signaling are integrated in the genome with Smad1 and β-catenin co-occupying DNA elements associated with hundreds of key regulatory genes. These results extend our understanding of GI organogenesis and how Wnt and BMP may coordinate genomic responses in other contexts.