Project description:The embryonic stem (ES) cell transcriptional and epigenetic networks are critical for the maintenance of ES cell self-renewal. It remains unclear whether interactions. Here we show that a core member of the Set/MLL complex, WDrepeat protein-5 (Wdr5), is a novel regulator of self-renewal and partners with Oct4 to maintain an intact transcriptional network and for efficient formation of induced pluripotent stem (iPS) cells. Moreover, we provide evidence that Oct4 interacts with chromatin components and is indispensible for epigenetic regulation. These findings suggest an integrated transcriptional and epigenetic model, mediated through Wdr5, for the maintenance of ES cell self-renewal and somatic cell reprogramming. Differential gene expressions upon down-regulation of Wdr5 was analysed by comparing Wdr5R4 –dox (triplicate) and LucR +dox (duplicate) RNA samples Gene expression changes upon down-regulation of Oct4 was analysed by comparing Oct4 shRNA (duplicate) and GFP shRNA (duplicate) after 4day transfection Wdr5: 5 samples are analyzed: Luciferase (Luc, 2 replicates) and Wdr5 with no dox (minusDox, 3 replicates) Oct4-GFP: 4 samples are analyzed: Oct4 shRNA (Oct4, 2 replicates) and GFP shRNA (GFP, 2 replicates)
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:The embryonic stem (ES) cell transcriptional and epigenetic networks are critical for the maintenance of ES cell self-renewal. It remains unclear whether interactions. Here we show that a core member of the Set/MLL complex, WDrepeat protein-5 (Wdr5), is a novel regulator of self-renewal and partners with Oct4 to maintain an intact transcriptional network and for efficient formation of induced pluripotent stem (iPS) cells. Moreover, we provide evidence that Oct4 interacts with chromatin components and is indispensible for epigenetic regulation. These findings suggest an integrated transcriptional and epigenetic model, mediated through Wdr5, for the maintenance of ES cell self-renewal and somatic cell reprogramming. Differential gene expressions upon down-regulation of Wdr5 was analysed by comparing Wdr5R4 –dox (triplicate) and LucR +dox (duplicate) RNA samples Gene expression changes upon down-regulation of Oct4 was analysed by comparing Oct4 shRNA (duplicate) and GFP shRNA (duplicate) after 4day transfection
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.
Project description:O-linked-N-acetylglucosamine (O-GlcNAc) has emerged as a critical regulator of diverse cellular processes, but its role in embryonic stem cells (ESCs) and pluripotency has not been investigated. Here we show that O-GlcNAcylation directly regulates core components of the pluripotency network. Blocking O-GlcNAcylation disrupts ESC self-renewal and reprogramming of somatic cells to induced pluripotent stem cells. The core reprogramming factors Oct4 and Sox2 are O-GlcNAcylated in ESCs, but the O-GlcNAc modification is rapidly removed upon differentiation. O-GlcNAc modification of Threonine 228 in Oct4 regulates Oct4 transcriptional activity and is important for inducing many pluripotency related genes, including Klf2, Klf5, Nr5a2, Tbx3 and Tcl1. A T228A point mutation that eliminates this O-GlcNAc modification reduces the capacity of Oct4 to maintain ESC self-renewal and reprogram somatic cells. Overall, our study makes a direct connection between O-GlcNAcylation of key regulatory transcription factors and the activity of the pluripotency network. 2 of E14 stem cell, 2 of embryonic body at day 2, 2 of embryonic body at day 2 treated with streptozotocin, 1 of ZHBTc4 stem cell treated with doxicyclin, and 1 of ZHBTc4 stem cell treated with doxicyclin and streptozotocin were analysed
Project description:Chavez2009 - a core regulatory network of OCT4 in human embryonic stem cells
A core OCT4-regulated network has been identified as a test case, to analyase stem cell characteristics and cellular differentiation.
This model is described in the article:
In silico identification of a core regulatory network of OCT4 in human embryonic stem cells using an integrated approach.
Chavez L, Bais AS, Vingron M, Lehrach H, Adjaye J, Herwig R
BMC Genomics, 2009, 10:314
Abstract:
BACKGROUND: The transcription factor OCT4 is highly expressed in pluripotent embryonic stem cells which are derived from the inner cell mass of mammalian blastocysts. Pluripotency and self renewal are controlled by a transcription regulatory network governed by the transcription factors OCT4, SOX2 and NANOG. Recent studies on reprogramming somatic cells to induced pluripotent stem cells highlight OCT4 as a key regulator of pluripotency.
RESULTS: We have carried out an integrated analysis of high-throughput data (ChIP-on-chip and RNAi experiments along with promoter sequence analysis of putative target genes) and identified a core OCT4 regulatory network in human embryonic stem cells consisting of 33 target genes. Enrichment analysis with these target genes revealed that this integrative analysis increases the functional information content by factors of 1.3 - 4.7 compared to the individual studies. In order to identify potential regulatory co-factors of OCT4, we performed a de novo motif analysis. In addition to known validated OCT4 motifs we obtained binding sites similar to motifs recognized by further regulators of pluripotency and development; e.g. the heterodimer of the transcription factors C-MYC and MAX, a prerequisite for C-MYC transcriptional activity that leads to cell growth and proliferation.
CONCLUSION: Our analysis shows how heterogeneous functional information can be integrated in order to reconstruct gene regulatory networks. As a test case we identified a core OCT4-regulated network that is important for the analysis of stem cell characteristics and cellular differentiation. Functional information is largely enriched using different experimental results. The de novo motif discovery identified well-known regulators closely connected to the OCT4 network as well as potential new regulators of pluripotency and differentiation. These results provide the basis for further targeted functional studies.
This model is hosted on BioModels Database
and identified
by: MODEL1305010000
.
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:O-linked-N-acetylglucosamine (O-GlcNAc) has emerged as a critical regulator of diverse cellular processes, but its role in embryonic stem cells (ESCs) and pluripotency has not been investigated. Here we show that O-GlcNAcylation directly regulates core components of the pluripotency network. Blocking O-GlcNAcylation disrupts ESC self-renewal and reprogramming of somatic cells to induced pluripotent stem cells. The core reprogramming factors Oct4 and Sox2 are O-GlcNAcylated in ESCs, but the O-GlcNAc modification is rapidly removed upon differentiation. O-GlcNAc modification of Threonine 228 in Oct4 regulates Oct4 transcriptional activity and is important for inducing many pluripotency related genes, including Klf2, Klf5, Nr5a2, Tbx3 and Tcl1. A T228A point mutation that eliminates this O-GlcNAc modification reduces the capacity of Oct4 to maintain ESC self-renewal and reprogram somatic cells. Overall, our study makes a direct connection between O-GlcNAcylation of key regulatory transcription factors and the activity of the pluripotency network.
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.