Blood vessels restrain pancreas branching, differentiation and growth
Ontology highlight
ABSTRACT: How organ size and form are controlled during development is a major question of biology. Blood vessels have been shown to be essential for early development of the liver and pancreas, and are fundamental to normal and pathological tissue growth. Here we report that non-nutritional signals from blood vessels surprisingly act to restrain pancreas growth. Elimination of endothelial cells increases the size of embryonic pancreatic buds. Conversely, VEGF-induced hypervascularization decreases pancreas size. The growth phenotype results from vascular restriction of pancreatic tip cell formation, lateral branching and differentiation of the pancreatic epithelium into endocrine and acinar cells. The effects are seen both in vivo and ex vivo, indicating a perfusion-independent mechanism. Thus the vasculature controls pancreas morphogenesis and growth by reducing branching and differentiation of primitive epithelial cells. For transcriptome analysis, RNA was isolated using QIAGEN RNeasy micro Kit from pancreatic buds of Pdx1-tTA (n=3) and littermate Pdx1-tTA; TET-VEGF (n=3) e12.5 embryos, or from e12.5 wild type pancreatic buds explanted and treated with VEGFR2i (n=5) or vehicle (n=5) for 2 days. Pooled samples were hybridized to Affymetrix mouse gene 1.0 st arrays. The arrays were RMA normalized using Partek Genomic Suite 6.5. Differentially regulated genes were selected based on p-values and ratios using t-test.
Project description:Identification of genes regulated by IPF1/PDX1 in early pancreatic progenitor cells, analysis of Ipf1/Pdx1 global null mutants e10.5 embryonic pancreatic buds compared to wt
Project description:To gain insights into how pancreatic beta-cells are programmed in vivo, we profiled key histone methylations (H3K4/K27me3) in embryonic stem cells, multipotent progenitors of the nascent embryonic pancreas, purified beta-cells, and 10 other adult tissues (all under normal, untreated conditions). For these cells we also purified RNA to analyze tissue specfic genome wide transcription levels in relation to histone modifications. Corresponding RNA microarrays can be found under accession E-TABM-877.
Project description:To gain insights into how pancreatic beta-cells are programmed in vivo, we profiled key histone methylations (H3K4/K27me3) in embryonic stem cells, multipotent progenitors of the nascent embryonic pancreas, purified beta-cells, and 10 other adult tissues (all under normal, untreated conditions). For these cells we also purified RNA to analyze tissue specfic genome wide transcription levels in relation to histone modifications.
Project description:Ptf1a was identified as the essential transcription factor which controls pancreatic exocrine enzyme expression. With lineage tracing eperiments Ptf1a was recognized as an important pancreatic progenitor transcription factor and Ptf1a null mice do not develop a pancreas. We used gene expression arrays to determine the global differeences in expression levels when pancreatic progenitor cells are expanding in Ptf1a heterozygote versus null mutants at E10.5. Ptf1a E10.5 dorsal pancreas total RNA from pools of 3 embryos was twice linear amplified and hybridized to Affymetrix GeneChip Mouse Genome 430 2.0 in triplicate for the Ptf1a KO and in duplicate for the Ptf1a heterozygote
Project description:Active regulatory regions in the human embryonic pancreatic progenitors were profiled by integration of transcription factor and histone modification ChIP-seq datasets. These were obtained from pancreatic progenitor cells derived in vitro from human embryonic stem cells. The purpose of this work was to study the epigenomic mechanisms involved in pancreas development.
Project description:The genomic regulatory programs that underlie human organogenesis are poorly understood. Human pancreas development, in particular, has pivotal implications for pancreatic regeneration, cancer, and diabetes. We have now created maps of transcripts, active enhancers, and transcription factor networks in pancreatic multipotent progenitors obtained from human embryos, or derived in vitro from human embryonic stem cells. This revealed that artificial progenitors recapitulate salient transcriptional and epigenomic features of their natural counterparts. Using this resource, we show that TEAD1, a transcription factor controlled by Hippo signaling, is a core component of the combinatorial code of pancreatic progenitor enhancers. TEAD thus activates genes encoding regulators of signaling pathways and stage-specific transcription factors that are essential for normal pancreas development. Accordingly, chemical and genetic perturbations of TEAD and its coactivator YAP inhibited expression of known regulators such as FGFR2 and SOX9, and suppressed the proliferation and expansion of mouse and zebrafish pancreatic progenitors. These findings provide a resource of active enhancers and transcripts in human pancreatic multipotent progenitors, and uncover a central role of TEAD and YAP as signal-responsive regulators of the transcriptional program of early pancreas development.
Project description:During embryogenesis, the pancreas develops from separate dorsal and ventral buds, which fuse to form the mature pancreas. Little is known about the functional differences between these two buds or the relative contribution of cells derived from each portion to the pancreas after fusion. To follow the fate of dorsal or ventral bud derived cells in the pancreas after fusion, we produced chimeric Elas-GFP transgenic/wild type embryos in which either dorsal or ventral pancreatic bud cells expressed GFP. We found that ventral pancreatic cells migrate extensively into the dorsal pancreas after fusion, whereas the converse does not occur. Moreover, we found that annular pancreatic tissue is composed exclusively of ventral pancreas derived cells. To identify ventral pancreas specific genes that may play a role in pancreatic bud fusion, we isolated individual dorsal and ventral pancreatic buds, prior to fusion, from stage 38/39 Xenopus laevis tadpoles and compared their gene expression profiles. Morpholino-mediated knockdown of one of these ventral specific genes, transmembrane 4 superfamily member 3 (tm4sf3), inhibited dorsal-ventral pancreatic bud fusion as well as acinar cell differentiation. Conversely, overexpression of tm4sf3 promoted the development of annular pancreas. Our results are the first to define molecular and behavioral differences between the dorsal and ventral pancreas, and suggest an unexpected role for the ventral pancreas in pancreatic bud fusion. Experiment Overall Design: We analyzed two samples of dorsal and two samples of ventral pancreatic buds.
Project description:Endoderm cells undergo a sequence of fate choices to generate insulin-secreting M-NM-2 cells. Studies of chromatin transitions during this process have been limited to the pancreatic progenitor stage that can be reconstituted from stem cells in vitro, with a gap in understanding the induction of endocrine cells. To address this, we established conditions for isolating endoderm cells, pancreatic progenitors, and endocrine cells from different staged embryos and performed genome wide analysis of the H3K27me3 mark of the repressive Polycomb complex. During the transition from endoderm to pancreas progenitors and during the transition from pancreas progenitors to endocrine cells, genes that lose the H3K27me3 mark typically encode transcriptional regulators, whereas genes that acquire the mark typically are involved in cell biology morphogenesis. Precocious depletion of the EZH2, a H3K27 methylase, at the pancreas progenitor stage enhanced the production of endocrine cells, leading to a later increase in pancreatic beta cells. Similarly, pharmacologic inhibition of EZH2 in embryonic pancreatic tissue explants and human embryonic stem cell cultures led to an increase in endocrine progenitors in vitro. These findings reveal a repeating target gene pattern in H3K27me3 dynamics and provide a means to modulate M-NM-2 cell development from stem cells. Analyzed five FACS-sorted tissues in early mouse embryo; for each tissue we sequenced H3K27me3 and input; no replicates
Project description:During embryogenesis, the pancreas develops from separate dorsal and ventral buds, which fuse to form the mature pancreas. Little is known about the functional differences between these two buds or the relative contribution of cells derived from each portion to the pancreas after fusion. To follow the fate of dorsal or ventral bud derived cells in the pancreas after fusion, we produced chimeric Elas-GFP transgenic/wild type embryos in which either dorsal or ventral pancreatic bud cells expressed GFP. We found that ventral pancreatic cells migrate extensively into the dorsal pancreas after fusion, whereas the converse does not occur. Moreover, we found that annular pancreatic tissue is composed exclusively of ventral pancreas derived cells. To identify ventral pancreas specific genes that may play a role in pancreatic bud fusion, we isolated individual dorsal and ventral pancreatic buds, prior to fusion, from stage 38/39 Xenopus laevis tadpoles and compared their gene expression profiles. Morpholino-mediated knockdown of one of these ventral specific genes, transmembrane 4 superfamily member 3 (tm4sf3), inhibited dorsal-ventral pancreatic bud fusion as well as acinar cell differentiation. Conversely, overexpression of tm4sf3 promoted the development of annular pancreas. Our results are the first to define molecular and behavioral differences between the dorsal and ventral pancreas, and suggest an unexpected role for the ventral pancreas in pancreatic bud fusion. Keywords: Developmental genomics