Project description:We have used mouse embryonic stem cells (ESCs) as a model to study the signaling mechanisms that regulate self-renewal and commitment to differentiation. We hypothesized that genes critical to stem cell fate would be dynamically regulated at the initiation of commitment. Time course microarray analysis following initiation of commitment led us to propose a model of ESC maintenance in which highly regulated transcription factors and chromatin remodeling genes (down-regulated in our time course) maintain repression of genes responsible for cell differentiation, morphogenesis and development (up-regulated in our time course). Microarrays of Oct4, Nanog and Sox2 shRNA knockdown cell lines confirmed predicted regulation of target genes. shRNA knockdowns of candidate genes were tested in a novel high throughput screen of self-renewal, confirming their role in ESC pluripotency. We have identified genes that are critical for self-renewal and those that initiate commitment and developed draft transcriptional networks that control self-renewal and early development. Keywords: genetic modification Gene expression in Oct4 knockdown, Sox2 knockdown and their empty vector contol ES cells was analyzed.
Project description:We have used mouse embryonic stem cells (ESCs) as a model to study the signaling mechanisms that regulate self-renewal and commitment to differentiation. We hypothesized that genes critical to stem cell fate would be dynamically regulated at the initiation of commitment. Time course microarray analysis following initiation of commitment led us to propose a model of ESC maintenance in which highly regulated transcription factors and chromatin remodeling genes (down-regulated in our time course) maintain repression of genes responsible for cell differentiation, morphogenesis and development (up-regulated in our time course). Microarrays of Oct4, Nanog and Sox2 shRNA knockdown cell lines confirmed predicted regulation of target genes. shRNA knockdowns of candidate genes were tested in a novel high throughput screen of self-renewal, confirming their role in ESC pluripotency. We have identified genes that are critical for self-renewal and those that initiate commitment and developed draft transcriptional networks that control self-renewal and early development. Keywords: genetic modification
Project description:Chickarmane2008 - Stem cell lineage - NANOG GATA-6 switch
In this work, a dynamical model of lineage
determination based upon a minimal circuit, as discussed in PMID: 17215298
, which contains the Oct4/Sox2/Nanog core as well its interaction
with a few other key genes is discussed.
This model is described in the article:
A computational model for understanding stem cell, trophectoderm and endoderm lineage determination.
Chickarmane V, Peterson C
PloS one. 2008, 3(10):e3478
Abstract:
BACKGROUND: Recent studies have associated the transcription factors, Oct4, Sox2 and Nanog as parts of a self-regulating network which is responsible for maintaining embryonic stem cell properties: self renewal and pluripotency. In addition, mutual antagonism between two of these and other master regulators have been shown to regulate lineage determination. In particular, an excess of Cdx2 over Oct4 determines the trophectoderm lineage whereas an excess of Gata-6 over Nanog determines differentiation into the endoderm lineage. Also, under/over-expression studies of the master regulator Oct4 have revealed that some self-renewal/pluripotency as well as differentiation genes are expressed in a biphasic manner with respect to the concentration of Oct4. METHODOLOGY/
PRINCIPAL FINDINGS: We construct a dynamical model of a minimalistic network, extracted from ChIP-on-chip and microarray data as well as literature studies. The model is based upon differential equations and makes two plausible assumptions; activation of Gata-6 by Oct4 and repression of Nanog by an Oct4-Gata-6 heterodimer. With these assumptions, the results of simulations successfully describe the biphasic behavior as well as lineage commitment. The model also predicts that reprogramming the network from a differentiated state, in particular the endoderm state, into a stem cell state, is best achieved by over-expressing Nanog, rather than by suppression of differentiation genes such as Gata-6.
CONCLUSIONS: The computational model provides a mechanistic understanding of how different lineages arise from the dynamics of the underlying regulatory network. It provides a framework to explore strategies of reprogramming a cell from a differentiated state to a stem cell state through directed perturbations. Such an approach is highly relevant to regenerative medicine since it allows for a rapid search over the host of possibilities for reprogramming to a stem cell state.
This model is hosted on BioModels Database
and identified
by: MODEL8389825246
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
Project description:Chickarmane2008 - Stem cell lineage determination
In this work, a dynamical model of lineage
determination based upon a minimal circuit, as discussed in PMID: 17215298
, which contains the Oct4/Sox2/Nanog core as well its interaction
with a few other key genes is discussed.
This model is described in the article:
A computational model for understanding stem cell, trophectoderm and endoderm lineage determination.
Chickarmane V, Peterson C
PloS one. 2008, 3(10):e3478
Abstract:
BACKGROUND: Recent studies have associated the transcription factors, Oct4, Sox2 and Nanog as parts of a self-regulating network which is responsible for maintaining embryonic stem cell properties: self renewal and pluripotency. In addition, mutual antagonism between two of these and other master regulators have been shown to regulate lineage determination. In particular, an excess of Cdx2 over Oct4 determines the trophectoderm lineage whereas an excess of Gata-6 over Nanog determines differentiation into the endoderm lineage. Also, under/over-expression studies of the master regulator Oct4 have revealed that some self-renewal/pluripotency as well as differentiation genes are expressed in a biphasic manner with respect to the concentration of Oct4. METHODOLOGY/
PRINCIPAL FINDINGS: We construct a dynamical model of a minimalistic network, extracted from ChIP-on-chip and microarray data as well as literature studies. The model is based upon differential equations and makes two plausible assumptions; activation of Gata-6 by Oct4 and repression of Nanog by an Oct4-Gata-6 heterodimer. With these assumptions, the results of simulations successfully describe the biphasic behavior as well as lineage commitment. The model also predicts that reprogramming the network from a differentiated state, in particular the endoderm state, into a stem cell state, is best achieved by over-expressing Nanog, rather than by suppression of differentiation genes such as Gata-6.
CONCLUSIONS: The computational model provides a mechanistic understanding of how different lineages arise from the dynamics of the underlying regulatory network. It provides a framework to explore strategies of reprogramming a cell from a differentiated state to a stem cell state through directed perturbations. Such an approach is highly relevant to regenerative medicine since it allows for a rapid search over the host of possibilities for reprogramming to a stem cell state.
This model is hosted on BioModels Database
and identified
by: MODEL8390025091
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
Project description:Polycomb group (PcG) proteins are highly conserved epigenetic transcriptional repressors important for the control of numerous developmental gene expression programs and have recently been implicated in the modulation of embryonic stem cell (ESC) identity. We identified the PcG protein PCL2 (polycomb-like 2) in a genome-wide screen for novel regulators of self-renewal and pluripotency and predicted that it would play an important role in mouse ESC fate determination. Using multiple biochemical strategies, we provide evidence that PCL2 is a novel Polycomb Repressive Complex 2 (PRC2)-associated protein in mouse ESCs. Knockdown of Pcl2 in ESCs resulted in heightened self-renewal characteristics, defects in differentiation and altered patterns of histone methylation. Through integration of global gene expression and promoter occupancy analyses of both PCL2 and PRC2 components EZH2 and SUZ12, we have predicted PCL2 target genes and formulated regulatory networks describing the role of PCL2 both in modulating transcription of ESC self-renewal genes in undifferentiated ESCs as well as developmental regulators during early commitment and differentiation. Cells were stably expressing Pcl2 shRNA or shRNA mismatch control sequences. Hybridizations of three biological replicates for both the control and Pcl2 shRNA clone were performed.
Project description:Stem cell fate is governed by the integration of intrinsic and extrinsic positive and negative signals upon inherent transcriptional networks. To identify novel embryonic stem cell (ESC) regulators and assemble transcriptional networks controlling ESC fate, we performed temporal expression microarray analyses of ESCs following the initiation of commitment and integrated these data with known genome-wide transcription factor binding. Effects of forced under- or over-expression of predicted novel regulators, defined as differentially expressed genes with potential binding sites for known regulators of pluripotency, demonstrated greater than 90% correspondence with predicted function, as assessed by functional and high content assays of self-renewal. We next assembled 43 theoretical transcriptional networks in ESCs, 82% (23 out of 28 tested) of which were supported by analysis of genome-wide expression in Oct4 knockdown cells. By using this integrative approach we have, for the first time, formulated novel networks describing gene repression of key developmental regulators in undifferentiated ESCs and successfully predicted the outcomes of genetic manipulation of these networks. Experiment Overall Design: 1, 3, and 5 days LIF differentiated ESCs, and 1 and 2 days RA differentiated ESCs
Project description:The embryonic stem (ES) cell transcriptional and epigenetic networks are critical for the maintenance of ES cell self-renewal. However, it remains unclear whether components of these networks functionally interact and if so, what factors mediate such interactions. Here we show that WD-repeat protein-5 (Wdr5), a core member of the mammalian Trithorax (trxG) complex, positively correlates with the undifferentiated state and is a novel regulator of ES cell self-renewal. We demonstrate that Wdr5, an ‘effector’ of H3K4 methylation, interacts with the pluripotency transcription factor Oct4. In concordance, genome-wide ChIP-Seq and transcriptome analyses demonstrate overlapping gene regulatory functions between Oct4 and Wdr5. We show that the Oct4-Sox2-Nanog circuitry cooperates with trxG for transcriptional activation of key self-renewal regulators. Furthermore, Wdr5 expression is required for the efficient formation of induced pluripotent stem (iPS) cells. Collectively, these findings implicate an integrated model of transcriptional and epigenetic control, mediated by select trxG members, for the maintenance of ES cell self-renewal and somatic cell reprogramming. 7 Samples
Project description:Many transcriptional and epigenetic networks must be integrated to maintain self-renewal and pluripotency in embryonic stem cells (ESCs) and to enable induced pluripotent stem cell (iPSC) reprogramming. Here, we explore the role of Zfp217 as a key transcriptional factor in maintaining ES cell self-renewal by permorming genome-wide ChIP-Seq analyses. Examination of Zfp217 binding profiling by high throughput sequencing in mouse stem cells
Project description:Polycomb group (PcG) proteins are highly conserved epigenetic transcriptional repressors important for the control of numerous developmental gene expression programs and have recently been implicated in the modulation of embryonic stem cell (ESC) identity. We identified the PcG protein PCL2 (polycomb-like 2) in a genome-wide screen for novel regulators of self-renewal and pluripotency and predicted that it would play an important role in mouse ESC fate determination. Using multiple biochemical strategies, we provide evidence that PCL2 is a novel Polycomb Repressive Complex 2 (PRC2)-associated protein in mouse ESCs. Knockdown of Pcl2 in ESCs resulted in heightened self-renewal characteristics, defects in differentiation and altered patterns of histone methylation. Through integration of global gene expression and promoter occupancy analyses of both PCL2 and PRC2 components EZH2 and SUZ12, we have predicted PCL2 target genes and formulated regulatory networks describing the role of PCL2 both in modulating transcription of ESC self-renewal genes in undifferentiated ESCs as well as developmental regulators during early commitment and differentiation.