Distinct modes of SMAD2 chromatin binding and remodeling shape the transcriptional response to Nodal/Activin signaling
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PROVIDER: PRJNA310622 | ENA |
REPOSITORIES: ENA
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Project description:During development, key processes are orchestrated by Nodal/Activin signaling via SMAD2. Interplay between the SMADs, co-factors and chromatin determines cell-type specific responses, but the sequence of events underpinning SMAD2-mediated transcription is unknown. We performed RNA-and ChIP-sequencing for SMAD2, RNA Polymerase II and various histone modifications in different signaling states. Integration of these data reveals a dynamic transcriptional network downstream of Nodal/Activin signaling regulated by SMAD2 acting via multiple mechanisms. Upon ligand stimulation, SMAD2 can bind to pre-acetylated nucleosome-depleted sites, but also to unacetylated closed chromatin, where it induces nucleosome displacement and histone acetylation. Importantly, SMAD2 binding is highly dynamic and does not directly correlate with the transcriptional kinetics of target genes. Moreover, we show that SMAD2 initiates transcription by inducing RNA Polymerase II recruitment. We therefore define new paradigms for SMAD2-dependent transcription and provide a framework to understand how cells correctly execute gene expression programs in response to Nodal/Activin signaling.
2016-12-31 | GSE77454 | GEO
Project description:During development, key processes are orchestrated by Nodal/Activin signaling via SMAD2. Interplay between the SMADs, co-factors and chromatin determines cell-type specific responses, but the sequence of events underpinning SMAD2-mediated transcription is unknown. We performed RNA-and ChIP-sequencing for SMAD2, RNA Polymerase II and various histone modifications in different signaling states. Integration of these data reveals a dynamic transcriptional network downstream of Nodal/Activin signaling regulated by SMAD2 acting via multiple mechanisms. Upon ligand stimulation, SMAD2 can bind to pre-acetylated nucleosome-depleted sites, but also to unacetylated closed chromatin, where it induces nucleosome displacement and histone acetylation. Importantly, SMAD2 binding is highly dynamic and does not directly correlate with the transcriptional kinetics of target genes. Moreover, we show that SMAD2 initiates transcription by inducing RNA Polymerase II recruitment. We therefore define new paradigms for SMAD2-dependent transcription and provide a framework to understand how cells correctly execute gene expression programs in response to Nodal/Activin signaling.
2016-12-31 | GSE76742 | GEO
Project description:Nodal and Activin are morphogens of the TGFbeta superfamily of signaling molecules that direct differential cell fate decisions in a dose- and distance-dependent manner. During early embryonic development the Nodal/Activin pathway is responsible for the specification of mesoderm, endoderm, node and mesendoderm. In contradiction to this drive towards cellular differentiation, the pathway also plays important roles in the maintenance of self-renewal and pluripotency in embryonic and epiblast stem cells. The molecular basis behind stem cell interpretation of Nodal/Activin signaling gradients and the undertaking of disparate cell fate decisions remains poorly understood. Here, we show that any perturbation of endogenous signaling levels in mouse ES cells leads to their exit from self renewal towards divergent differentiation programs. Increasing Nodal signals above basal levels by direct stimulation with Activin promotes differentiation towards the mesendodermal lineages while repression of signaling with the specific Nodal/Activin receptor inhibitor SB431542 induces trophectodermal differentiation. To address how quantitative Nodal/Activin signals are translated qualitatively into distinct cell fates decisions, we performed chromatin immunoprecipitation of phospho-Smad2 the primary downstream transcriptional factor of the Nodal/Activin pathway followed by massively parallel sequencing and show that phospho-Smad2 binds to and regulates distinct subsets of target genes in a dose-dependent manner. Crucially, Nodal/Activin signaling directly controls the Oct4 master regulator of pluripotency by graded phospho-Smad2 binding in the promoter region. Hence stem cells interpret and carry out differential Nodal/Activin signaling instructions via a corresponding gradient of Smad2 phosphorylation that selectively titrates self-renewal against alternative differentiation programs by direct regulation of distinct target gene subsets and Oct4 expression. Four biological replicates consisting of 4 different passages of E14TG2a ES cells at P20, P21, P23 and P24
2011-06-30 | E-GEOD-23239 | biostudies-arrayexpress
Project description:Nodal and Activin are morphogens of the TGFbeta superfamily of signaling molecules that direct differential cell fate decisions in a dose- and distance-dependent manner. During early embryonic development the Nodal/Activin pathway is responsible for the specification of mesoderm, endoderm, node and mesendoderm. In contradiction to this drive towards cellular differentiation, the pathway also plays important roles in the maintenance of self-renewal and pluripotency in embryonic and epiblast stem cells. The molecular basis behind stem cell interpretation of Nodal/Activin signaling gradients and the undertaking of disparate cell fate decisions remains poorly understood. Here, we show that any perturbation of endogenous signaling levels in mouse ES cells leads to their exit from self renewal towards divergent differentiation programs. Increasing Nodal signals above basal levels by direct stimulation with Activin promotes differentiation towards the mesendodermal lineages while repression of signaling with the specific Nodal/Activin receptor inhibitor SB431542 induces trophectodermal differentiation. To address how quantitative Nodal/Activin signals are translated qualitatively into distinct cell fates decisions, we performed chromatin immunoprecipitation of phospho-Smad2 the primary downstream transcriptional factor of the Nodal/Activin pathway followed by massively parallel sequencing and show that phospho-Smad2 binds to and regulates distinct subsets of target genes in a dose-dependent manner. Crucially, Nodal/Activin signaling directly controls the Oct4 master regulator of pluripotency by graded phospho-Smad2 binding in the promoter region. Hence stem cells interpret and carry out differential Nodal/Activin signaling instructions via a corresponding gradient of Smad2 phosphorylation that selectively titrates self-renewal against alternative differentiation programs by direct regulation of distinct target gene subsets and Oct4 expression.
2011-06-30 | GSE23239 | GEO
Project description:Activin/Nodal signalling is necessary to maintain pluripotency of human Embryonic Stem Cells (hESCs) and to induce their differentiation towards endoderm. However, the mechanisms by which Activin/Nodal signalling achieves these opposite functions remain unclear. To unravel these mechanisms, we examined the transcriptional network controlled in hESCs by Smad2 and Smad3 which represent the direct effectors of Activin/Nodal signalling. These analyses reveal that Smad2/3 participate in the control of the core transcriptional network characterising pluripotency which includes Oct-4, Nanog, FoxD3, Dppa4, Tert, Myc and UTF-1. In addition, similar experiments performed on endoderm cells confirm that a broad part of the transcriptional network directing differentiation is downstream of Smad2/3. Therefore, Activin/Nodal signalling appears to control divergent transcriptional networks in hESCs and in endoderm. Importantly, we observed an overlap between the transcriptional network downstream of Nanog and Smad2/3 in hESCs while functional studies showed that both factors cooperate to control the expression of pluripotency genes. Therefore, the effect of Activin/Nodal signalling on pluripotency and differentiation could be dictated by tissue specific Smad2/3 partners such as Nanog, explaining the mechanisms by which signalling pathways can orchestrate divergent cell fate decisions. Identification of Smad2/3 binding sites in pluripotent hESCs. 5 ChIP-Seq samples including 1 input control sample and 4 ChIP samples (two conditions x two replicates).
2011-11-11 | E-GEOD-19461 | biostudies-arrayexpress
Project description:The Nodal/Activin morphogens are secreted signaling molecules that form concentration gradients during early embryogenesis providing stem cells with positional information and differentiation instructions important for embryonic patterning. The molecular basis driving stem cell interpretation of signaling gradients and the undertaking of distinct cell fate decisions remains poorly understood. We show that perturbation of endogenous Nodal/Activin signaling in ES cells leads to exit from self renewal towards mesendodermal differentiation at high signaling and trophectoderm induction during low signaling. ChIP-seq of Phospho-Smad2, the downstream transcription factor of the Nodal/Activin pathway reveals binding to distinct subsets of target genes in a dose dependent manner including the promoter region of the Oct4 master regulator of stemness. Consequently, both Oct4 mRNA and protein levels are directly driven by graded Nodal/Activin signaling. Hence stem cells interpret and carry out differential Nodal/Activin signaling instructions via a corresponding gradient of Smad2 phosphorylation that selectively titers self renewal against alternative differentiation programs. 3 pSmad2 ChIP samples corresponding to ES cells pretreated for 6 hours in 10uM SB followed by 18 hours in 25ng/ml Activin, 1/5000 DMSO and 10uM SB in 20% KSR media. Controls include the corresponding input DNA for each treatment.
2011-01-31 | E-GEOD-23581 | biostudies-arrayexpress
Project description:The Nodal/Activin morphogens are secreted signaling molecules that form concentration gradients during early embryogenesis providing stem cells with positional information and differentiation instructions important for embryonic patterning. The molecular basis driving stem cell interpretation of signaling gradients and the undertaking of distinct cell fate decisions remains poorly understood. We show that perturbation of endogenous Nodal/Activin signaling in ES cells leads to exit from self renewal towards mesendodermal differentiation at high signaling and trophectoderm induction during low signaling. ChIP-seq of Phospho-Smad2, the downstream transcription factor of the Nodal/Activin pathway reveals binding to distinct subsets of target genes in a dose dependent manner including the promoter region of the Oct4 master regulator of stemness. Consequently, both Oct4 mRNA and protein levels are directly driven by graded Nodal/Activin signaling. Hence stem cells interpret and carry out differential Nodal/Activin signaling instructions via a corresponding gradient of Smad2 phosphorylation that selectively titers self renewal against alternative differentiation programs.
2011-01-31 | GSE23581 | GEO
Project description:Activin/Nodal signalling is necessary to maintain pluripotency of human Embryonic Stem Cells (hESCs) and to induce their differentiation towards endoderm. However, the mechanisms by which Activin/Nodal signalling achieves these opposite functions remain unclear. To unravel these mechanisms, we examined the transcriptional network controlled in hESCs by Smad2 and Smad3 which represent the direct effectors of Activin/Nodal signalling. These analyses reveal that Smad2/3 participate in the control of the core transcriptional network characterising pluripotency which includes Oct-4, Nanog, FoxD3, Dppa4, Tert, Myc and UTF-1. In addition, similar experiments performed on endoderm cells confirm that a broad part of the transcriptional network directing differentiation is downstream of Smad2/3. Therefore, Activin/Nodal signalling appears to control divergent transcriptional networks in hESCs and in endoderm. Importantly, we observed an overlap between the transcriptional network downstream of Nanog and Smad2/3 in hESCs while functional studies showed that both factors cooperate to control the expression of pluripotency genes. Therefore, the effect of Activin/Nodal signalling on pluripotency and differentiation could be dictated by tissue specific Smad2/3 partners such as Nanog, explaining the mechanisms by which signalling pathways can orchestrate divergent cell fate decisions.
2011-11-11 | GSE19461 | GEO
Project description:Members of the transforming growth factor (TGF)-β superfamily play essential roles in the pluripotency, self-renewal, and differentiation of embryonic stem cells. While bone morphogenic proteins maintain pluripotency of undifferentiated mouse ES cells, the role of Activin/Nodal signaling is less clear. To determine the target genes of Activin/Nodal-Smad2 signaling in undifferentiated embryonic stem cells, changes in gene expression were examined following stimulation with recombinant Activin (2 hours) or after inhibition of Activin/Nodal with SB431542 (24 hours) using defined media culture conditions with LIF and 20 ng/mL BMP4. SB431542 is a specific inhibitor of ALK4/5/7 receptors and antagonizes both Activin and Nodal signaling. Via western analysis, Activin stimulation increased pSmad2 in ES cells after 2 hours, and treatment with SB431542 for 24 hours virtually eliminated pSmad2. Total Smad2 expression remained unchanged through these manipulations. RNA from cells treated with Activin or SB431542 was extracted by standard methods with Qiagen RNeasy columns. The RNA was analyzed with the Mouse Genome 430A Array from Affymetrix. Samples were performed in duplicate, and RNA from cells treated with Activin or SB431542 was compared to untreated embryonic stem cells.
2009-08-31 | GSE17879 | GEO
Project description:Members of the transforming growth factor (TGF)-β superfamily play essential roles in the pluripotency, self-renewal, and differentiation of embryonic stem cells. While bone morphogenic proteins maintain pluripotency of undifferentiated mouse ES cells, the role of Activin/Nodal signaling is less clear. To determine the target genes of Activin/Nodal-Smad2 signaling in undifferentiated embryonic stem cells, changes in gene expression were examined following stimulation with recombinant Activin (2 hours) or after inhibition of Activin/Nodal with SB431542 (24 hours) using defined media culture conditions with LIF and 20 ng/mL BMP4. SB431542 is a specific inhibitor of ALK4/5/7 receptors and antagonizes both Activin and Nodal signaling. Via western analysis, Activin stimulation increased pSmad2 in ES cells after 2 hours, and treatment with SB431542 for 24 hours virtually eliminated pSmad2. Total Smad2 expression remained unchanged through these manipulations. RNA from cells treated with Activin or SB431542 was extracted by standard methods with Qiagen RNeasy columns. The RNA was analyzed with the Mouse Genome 430A Array from Affymetrix. Samples were performed in duplicate, and RNA from cells treated with Activin or SB431542 was compared to untreated embryonic stem cells. Experiment Overall Design: RNA from cells treated with Activin or SB431542 was extracted by standard methods with Qiagen RNeasy columns. The RNA was analyzed with the Mouse Genome 430A Array from Affymetrix. Samples were performed in duplicate, and RNA from cells treated with Activin or SB431542 was compared to untreated embryonic stem cells.
2009-09-12 | E-GEOD-17879 | biostudies-arrayexpress