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.
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.
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.
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
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.
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.
Project description:Bone morphogenetic protein (BMP) signaling is known to support differentiation of human embryonic stem cells (hESCs) into mesoderm and extraembryonic lineages, whereas other signaling pathways can largely influence this lineage specification. Here, we set out to reinvestigate the influence of ACTIVIN/NODAL and fibroblast growth factor (FGF) pathways on the lineage choices made by hESCs during BMP4-driven differentiation. We show that BMP activation, coupled with inhibition of both ACTIVIN/NODAL and FGF signaling, induces differentiation of hESCs, specifically to M-NM-2hCG hormone-secreting multinucleated syncytiotrophoblast and does not support induction of embryonic and extraembryonic lineages, extravillous trophoblast, and primitive endoderm. It has been previously reported that FGF2 can switch BMP4-induced hESC differentiation outcome to mesendoderm. Here, we show that FGF inhibition alone, or in combination with either ACTIVIN/NODAL inhibition or BMP activation, supports hESC differentiation to hCG-secreting syncytiotrophoblast. We show that the inhibition of the FGF pathway acts as a key in directing BMP4-mediated hESC differentiation to syncytiotrophoblast. Human embryonic Stem Cells (hESCs) were treated under defined conditions (N2B27) with BMP4 (B), SB431542 (SB) (ACTIVIN/NODAL inhibitor), SU5402 (SU) (FGFR1 inhibitor), FGF2 (F) either alone or in various combinations as mentioned, followed by isolation of total RNA.
Project description:Activin/Nodal/TGF-β signaling pathway plays a major role in maintaining mouse epiblast stem cells (mEpiSCs). The mEpiSC medium which contains Activin A and bFGF induces differentiation of mouse embryonic stem cells (mESCs) to mEpiSC. Here we show that Activin A also has an ability to efficiently propagate mESCs without differentiation to mEpiSCs when combined with a MEK inhibitor PD0325901. mESCs cultured in Activin+PD retained high-level expression of naive pluripotency-related transcription factors. Genome-wide analysis revealed that the gene expression profile of mESCs cultured in Activin+PD resembles that of mESCs cultured in 2i. mESCs cultured in Activin+PD also showed features which are related to naive pluripotency of mESCs, including the preferential usage of the Oct4 distal enhancer and the self-renewal response to Wnt pathway activation. Our finding reveals a role of Activin/Nodal/TGF-β signaling in stabilizing self-renewal gene regulatory networks in mESCs. To compare the gene expression patterns of mESCs cultured in Activin+PD, 2i and LIF+BMP4 and mEpiSCs, we performed genome-wide gene expression analysis by using Affymetrix GeneChip oligonucleotide microarrays
Project description:Nodal/Activin signaling directs mesendoderm specification in early vertebrate embryogenesis. We have characterized transcriptional profiling of human embryonic stem cells and Activin-treated cells at different timepoints. In this dataset, we include the timecourse gene expression data obtained from hESC differentiation post Activin treatment, examining at day 0, 1, 3 and 5.
Project description:Human Embryonic Stem Cells (hESC) grown in chemically defined medium (CDM) supplemented with Activin and FGF were compared to hESCs grown for 48 hours in CDM supplemented with FGF2 and SB431542, an inhibitor of Activin/Nodal signalling. The objective of this experiment was to discover the identity of genes controlled by Activin/Nodal signalling in hESCs.<br><br>