Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Dynamics of Genomic H3K27me3 Domains and Role of EZH2 during Pancreatic Endocrine Specification

ABSTRACT: 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

ORGANISM(S): Mus musculus

SUBMITTER: Gregory Donahue

PROVIDER: E-GEOD-56617 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Aims/hypothesis: Duct cells isolated from adult human pancreas can be reprogrammed to express islet beta cell genes by adenoviral transduction of the developmental transcription factor neurogenin3 (Ngn3). In this study we aimed to fully characterize the extent of this reprogramming and intended to improve it. Methods: The extent of the Ngn3-mediated duct-to-endocrine cell reprogramming was measured employing genome wide mRNA profiling. By modulation of the Delta-Notch signaling or addition of pancreatic endocrine transcription factors Myt1, MafA and Pdx1 we intended to improve the reprogramming. Results: Ngn3 stimulates duct cells to express a focused set of genes that are abundant in islet endocrine cells and/or neural tissues. This neuro-endocrine shift, however, covers a minor fraction (5%) of the estimated genome-wide transcriptome difference between duct and islet endocrine cells. Interestingly, transduction of exogenous Ngn3 activates endogenous Ngn3 suggesting auto-activation of this gene. Furthermore, pancreatic endocrine reprogramming of human duct cells can be moderately enhanced by inhibition of Delta-Notch signaling as well as by co-expressing the transcription factor Myt1, but not MafA and Pdx1. Conclusions/interpretation: The results provide further insight into the plasticity of adult human duct cells and suggest measurable routes to enhance Ngn3-mediated in vitro reprogramming protocols for regenerative beta cell therapy in diabetes. We used Affymetrix HG133A and HG133B to get a comprehensive view on the reprogramming potential in vitro of human pancreatic duct cell cultures (n=3-4) at 3 and 14/20 days after ectopic adenoviral expression of murine neurogenin 3 as compared to GFP-expressing control vectors. The microarray analysis was performed on 3 independent samples that each contained RNA extracted from a pool of 3 independent donor pancreata. The total number of non-selected donor organs is 9. Transcripts were considered as differentially regulated by Ngn3 when 1.5 fold (LCB, unpaired P < 0.05) up- or down-regulated in AdGFP-Ngn3 versus AdGFP controls, at 3 and/or 14 dpi. Transcripts that showed differential expression between day 3 and day 14 in AdGFP-Ngn3 duct cells but not in AdGFP control cells, were also considered Ngn3-regulated

Project description:Understanding how distinct cell types arise from common multipotent progenitor cells is a major quest in stem cell biology. This knowledge will aid in the targeted differentiation and growth of stem cells, but also in the discovery of the basis of cellular plasticity and of how tissue programming can be controlled. The liver and pancreas share many aspects of their early development, being both specified in the same region of the endoderm, and, possibly, originating from a common progenitor. However, how pancreas versus liver cell fate decision occurs during embryogenesis and the molecular basis of this cellular plasticity are poorly understood. Here, we use RNA-Seq to define the molecular identity of liver and pancreas progenitors directly in mouse embryos and to investigate the mechanisms regulating the emergence of liver or pancreas as alternative fates from the endoderm. Progenitor cell-specific RNA was obtained from mouse Prox1-EGFP-labeled embryonic cells isolated by FACS at distinct developmental stages, before and after the onset of organogenesis. By integrating the temporal and spatial gene expression profiles, we found mutually exclusive signaling signatures in hepatic and pancreatic progenitors. Importantly, we identified the non-canonical Wnt pathway as a potential developmental regulator of the pancreas versus liver fate decision, being expressed in the foregut endoderm, before the cell fate choice is made, and then maintained in pancreas progenitors but absent in hepatic progenitors. Moreover, when assayed in Xenopus embryos, the non-canonical Wnt pathway is able to promote pancreatic fate and repress hepatic fate in the endoderm, suggesting an ancient mechanism for controlling pancreas versus liver fate choice. We expect that this knowledge will be key to formulate reprogramming strategies to convert adult hepatic cells into pancreatic cells as a cell-based therapeutic approach for diabetes. We performed sequencing-based expression profiling (RNA-Seq) of hepatic and pancreatic progenitors in the mouse at two distinct developmental stages.

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Dynamics of Genomic H3K27me3 Domains and Role of EZH2 during Pancreatic Endocrine Specification

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