Project description:TCF7L1 is a member of the T cell factor/Lymphoid enhancer factor (TCF/LEF) family of tran-scription factors that are part of the WNT/beta-CATENIN signaling pathway. TCF7L1 modulates transcription by interacting with other regulators on chromatin. TCF7L1 has been shown to be one of the key factors in maintaining pluripotency in human embryonic stem cells (ESCs). We previously demonstrated that the absence of TCF71 causes H9 hESCs to differentiate sponta-neously (Sierra et al., 2018 Development 145(4).pii:dev161075). Mechanistically, how TCF7L1 inhibits differentiation and keeps cells in the pluripotent state is not clear. Identifying transcrip-tional regulators on chromatin is a critical step to elucidating one of several molecular mecha-nisms controlled by TCF7L1. We previously developed a FLAG tagged TCF7L1 transgene that is controlled by a doxycycline-inducible TET-ON system and generated the H9-TCF7L1 line (Sier-ra et al., 2018 Development 145(4).pii:dev161075). Here we used the H9-TCF7L1 line and em-ployed the method called rapid immunoprecipitation (IP) mass spectrometry of endogenous pro-tein (RIME) (Mohammed et al., 2016 Nat Protoc 11(2):316-26) to identify TCF7L1-associated proteins on chromatin. Coupling of these two methods (the FLAG tagged TETON inducible sys-tem and RIME) allowed us to control the level of TCF7L1 expression in hESCs, immunopreci-pate TCF7L1 using an anti-FLAG antibody and capture TCF7L1-bound associated complexes on chromatin. Our MS analysis identified some known proteins that have been shown to associate with the WNT/beta-CATENIN/TCF/LEF pathway, as well as novel complexes that have not been linked with TCF7L1. Gene Ontology analysis suggest these proteins function in chromatin modi-fication, splicing, and RNA processing. Our data could create new ideas for in-depth studies of TCF7L1 controlling pluripotency in human ESCs and for understanding how TCF7L1 may act in other cell types.
Project description:The cellular microenvironment shapes stem cell identity and differentiation capacity. Mammalian early embryos are exposed to hypoxia in vivo and benefit from hypoxic culture in vitro. Yet, how different components of the hypoxia response impact stem cell transcriptional networks and lineage choices remains unclear. Here we investigated the effect of acute and prolonged hypoxia on stem cell states and differentiation efficiencies of embryonic and extraembryonic cells. We show that prolonged hypoxia enhances differentiation of embryonic stem (ES) cells towards the mesendoderm lineage by transcriptionally priming cells with a primitive streak signature including Wnt3 and T expression. Exposure to hypoxia in ES culture or during formation of gastrulation-mimicking organoids (gastruloids) moderates T expression and enhances structural complexity. Hypoxic gastruloids generated without exogenous Wnt induction can spontaneously elongate and self-organize. Direct gene regulation by Hif1a, combined with DNA demethylation and metabolic rewiring modulate the transcriptional response and phenotypic outcome. Our findings highlight the influence of the microenvironment on stem cell function and provide a rationale supportive of applying physiological conditions in synthetic embryo models.
Project description:Gastrulation initiates when the epiblast differentiates into either definitive ectoderm or primitive streak. During the lineage bifurcation, the DNA dioxygenase TET1 plays dual roles in both transcriptional activation and repression, but how it exerts this bipartite control via 5-methylcytosine (5mC) oxidation-dependent and independent activities remains unclear. Here, we perform a monolayer differentiation of mouse embryonic stem cells (ESCs) into neuronal precursors to define at single-cell resolution how Tet1-/- cells undergo a lineage switch to primitive streak and subsequently form mesoderm and endoderm. We identify the Wnt repressor Tcf7l1 as a direct target of TET1 that controls a signaling cascade of Wnt/β-catenin upstream of Nodal. Disrupting the endogenous catalytic site of Tet1 in ESCs contributes to activation of Nodal and subsequently Wnt/β-catenin signaling, promoting tri-lineage differentiation into ectoderm, mesoderm and endoderm. Catalytically dead TET1 is sufficient in sustaining open neuroectoderm enhancers, by which gene expression is uncoupled from enhancer DNA demethylation, and indirectly keeping primitive streak enhancers inaccessible to Wnt regulators and effectors. DNA hypermethylation caused by TET1 catalytic dysfunction instead promotes precocious primitive streak gene activation when associated with CpG islands overlapping bivalent gene promotors. Moreover, hypermethylated regions amplify in numbers in the absence of TET1 through differentiation to affect genes associated with neurological functions. Our results reveal two-way safeguarding activities of TET1 separable by genomic features, where at CpG-poor distal enhancers TET1 maintains accessible chromatin permissive for neural fate independently of 5mC oxidation; at CpG-rich bivalent promoters it prevents premature gene activation inducing alternative fates by harnessing 5mC oxidation in Polycomb gene repression.
Project description:Gastrulation initiates when the epiblast differentiates into either definitive ectoderm or primitive streak. During the lineage bifurcation, the DNA dioxygenase TET1 plays dual roles in both transcriptional activation and repression, but how it exerts this bipartite control via 5-methylcytosine (5mC) oxidation-dependent and independent activities remains unclear. Here, we perform a monolayer differentiation of mouse embryonic stem cells (ESCs) into neuronal precursors to define at single-cell resolution how Tet1-/- cells undergo a lineage switch to primitive streak and subsequently form mesoderm and endoderm. We identify the Wnt repressor Tcf7l1 as a direct target of TET1 that controls a signaling cascade of Wnt/β-catenin upstream of Nodal. Disrupting the endogenous catalytic site of Tet1 in ESCs contributes to activation of Nodal and subsequently Wnt/β-catenin signaling, promoting tri-lineage differentiation into ectoderm, mesoderm and endoderm. Catalytically dead TET1 is sufficient in sustaining open neuroectoderm enhancers, by which gene expression is uncoupled from enhancer DNA demethylation, and indirectly keeping primitive streak enhancers inaccessible to Wnt regulators and effectors. DNA hypermethylation caused by TET1 catalytic dysfunction instead promotes precocious primitive streak gene activation when associated with CpG islands overlapping bivalent gene promotors. Moreover, hypermethylated regions amplify in numbers in the absence of TET1 through differentiation to affect genes associated with neurological functions. Our results reveal two-way safeguarding activities of TET1 separable by genomic features, where at CpG-poor distal enhancers TET1 maintains accessible chromatin permissive for neural fate independently of 5mC oxidation; at CpG-rich bivalent promoters it prevents premature gene activation inducing alternative fates by harnessing 5mC oxidation in Polycomb gene repression.
Project description:Gastrulation initiates when the epiblast differentiates into either definitive ectoderm or primitive streak. During the lineage bifurcation, the DNA dioxygenase TET1 plays dual roles in both transcriptional activation and repression, but how it exerts this bipartite control via 5-methylcytosine (5mC) oxidation-dependent and independent activities remains unclear. Here, we perform a monolayer differentiation of mouse embryonic stem cells (ESCs) into neuronal precursors to define at single-cell resolution how Tet1-/- cells undergo a lineage switch to primitive streak and subsequently form mesoderm and endoderm. We identify the Wnt repressor Tcf7l1 as a direct target of TET1 that controls a signaling cascade of Wnt/β-catenin upstream of Nodal. Disrupting the endogenous catalytic site of Tet1 in ESCs contributes to activation of Nodal and subsequently Wnt/β-catenin signaling, promoting tri-lineage differentiation into ectoderm, mesoderm and endoderm. Catalytically dead TET1 is sufficient in sustaining open neuroectoderm enhancers, by which gene expression is uncoupled from enhancer DNA demethylation, and indirectly keeping primitive streak enhancers inaccessible to Wnt regulators and effectors. DNA hypermethylation caused by TET1 catalytic dysfunction instead promotes precocious primitive streak gene activation when associated with CpG islands overlapping bivalent gene promotors. Moreover, hypermethylated regions amplify in numbers in the absence of TET1 through differentiation to affect genes associated with neurological functions. Our results reveal two-way safeguarding activities of TET1 separable by genomic features, where at CpG-poor distal enhancers TET1 maintains accessible chromatin permissive for neural fate independently of 5mC oxidation; at CpG-rich bivalent promoters it prevents premature gene activation inducing alternative fates by harnessing 5mC oxidation in Polycomb gene repression.
Project description:Gastrulation initiates when the epiblast differentiates into either definitive ectoderm or primitive streak. During the lineage bifurcation, the DNA dioxygenase TET1 plays dual roles in both transcriptional activation and repression, but how it exerts this bipartite control via 5-methylcytosine (5mC) oxidation-dependent and independent activities remains unclear. Here, we perform a monolayer differentiation of mouse embryonic stem cells (ESCs) into neuronal precursors to define at single-cell resolution how Tet1-/- cells undergo a lineage switch to primitive streak and subsequently form mesoderm and endoderm. We identify the Wnt repressor Tcf7l1 as a direct target of TET1 that controls a signaling cascade of Wnt/β-catenin upstream of Nodal. Disrupting the endogenous catalytic site of Tet1 in ESCs contributes to activation of Nodal and subsequently Wnt/β-catenin signaling, promoting tri-lineage differentiation into ectoderm, mesoderm and endoderm. Catalytically dead TET1 is sufficient in sustaining open neuroectoderm enhancers, by which gene expression is uncoupled from enhancer DNA demethylation, and indirectly keeping primitive streak enhancers inaccessible to Wnt regulators and effectors. DNA hypermethylation caused by TET1 catalytic dysfunction instead promotes precocious primitive streak gene activation when associated with CpG islands overlapping bivalent gene promotors. Moreover, hypermethylated regions amplify in numbers in the absence of TET1 through differentiation to affect genes associated with neurological functions. Our results reveal two-way safeguarding activities of TET1 separable by genomic features, where at CpG-poor distal enhancers TET1 maintains accessible chromatin permissive for neural fate independently of 5mC oxidation; at CpG-rich bivalent promoters it prevents premature gene activation inducing alternative fates by harnessing 5mC oxidation in Polycomb gene repression.
Project description:Gastrulation initiates when the epiblast differentiates into either definitive ectoderm or primitive streak. During the lineage bifurcation, the DNA dioxygenase TET1 plays dual roles in both transcriptional activation and repression, but how it exerts this bipartite control via 5-methylcytosine (5mC) oxidation-dependent and independent activities remains unclear. Here, we perform a monolayer differentiation of mouse embryonic stem cells (ESCs) into neuronal precursors to define at single-cell resolution how Tet1-/- cells undergo a lineage switch to primitive streak and subsequently form mesoderm and endoderm. We identify the Wnt repressor Tcf7l1 as a direct target of TET1 that controls a signaling cascade of Wnt/β-catenin upstream of Nodal. Disrupting the endogenous catalytic site of Tet1 in ESCs contributes to activation of Nodal and subsequently Wnt/β-catenin signaling, promoting tri-lineage differentiation into ectoderm, mesoderm and endoderm. Catalytically dead TET1 is sufficient in sustaining open neuroectoderm enhancers, by which gene expression is uncoupled from enhancer DNA demethylation, and indirectly keeping primitive streak enhancers inaccessible to Wnt regulators and effectors. DNA hypermethylation caused by TET1 catalytic dysfunction instead promotes precocious primitive streak gene activation when associated with CpG islands overlapping bivalent gene promotors. Moreover, hypermethylated regions amplify in numbers in the absence of TET1 through differentiation to affect genes associated with neurological functions. Our results reveal two-way safeguarding activities of TET1 separable by genomic features, where at CpG-poor distal enhancers TET1 maintains accessible chromatin permissive for neural fate independently of 5mC oxidation; at CpG-rich bivalent promoters it prevents premature gene activation inducing alternative fates by harnessing 5mC oxidation in Polycomb gene repression.
Project description:Gastrulation initiates when the epiblast differentiates into either definitive ectoderm or primitive streak. During the lineage bifurcation, the DNA dioxygenase TET1 plays dual roles in both transcriptional activation and repression, but how it exerts this bipartite control via 5-methylcytosine (5mC) oxidation-dependent and independent activities remains unclear. Here, we perform a monolayer differentiation of mouse embryonic stem cells (ESCs) into neuronal precursors to define at single-cell resolution how Tet1-/- cells undergo a lineage switch to primitive streak and subsequently form mesoderm and endoderm. We identify the Wnt repressor Tcf7l1 as a direct target of TET1 that controls a signaling cascade of Wnt/β-catenin upstream of Nodal. Disrupting the endogenous catalytic site of Tet1 in ESCs contributes to activation of Nodal and subsequently Wnt/β-catenin signaling, promoting tri-lineage differentiation into ectoderm, mesoderm and endoderm. Catalytically dead TET1 is sufficient in sustaining open neuroectoderm enhancers, by which gene expression is uncoupled from enhancer DNA demethylation, and indirectly keeping primitive streak enhancers inaccessible to Wnt regulators and effectors. DNA hypermethylation caused by TET1 catalytic dysfunction instead promotes precocious primitive streak gene activation when associated with CpG islands overlapping bivalent gene promotors. Moreover, hypermethylated regions amplify in numbers in the absence of TET1 through differentiation to affect genes associated with neurological functions. Our results reveal two-way safeguarding activities of TET1 separable by genomic features, where at CpG-poor distal enhancers TET1 maintains accessible chromatin permissive for neural fate independently of 5mC oxidation; at CpG-rich bivalent promoters it prevents premature gene activation inducing alternative fates by harnessing 5mC oxidation in Polycomb gene repression.
Project description:Gastrulation initiates when the epiblast differentiates into either definitive ectoderm or primitive streak. During the lineage bifurcation, the DNA dioxygenase TET1 plays dual roles in both transcriptional activation and repression, but how it exerts this bipartite control via 5-methylcytosine (5mC) oxidation-dependent and independent activities remains unclear. Here, we perform a monolayer differentiation of mouse embryonic stem cells (ESCs) into neuronal precursors to define at single-cell resolution how Tet1-/- cells undergo a lineage switch to primitive streak and subsequently form mesoderm and endoderm. We identify the Wnt repressor Tcf7l1 as a direct target of TET1 that controls a signaling cascade of Wnt/β-catenin upstream of Nodal. Disrupting the endogenous catalytic site of Tet1 in ESCs contributes to activation of Nodal and subsequently Wnt/β-catenin signaling, promoting tri-lineage differentiation into ectoderm, mesoderm and endoderm. Catalytically dead TET1 is sufficient in sustaining open neuroectoderm enhancers, by which gene expression is uncoupled from enhancer DNA demethylation, and indirectly keeping primitive streak enhancers inaccessible to Wnt regulators and effectors. DNA hypermethylation caused by TET1 catalytic dysfunction instead promotes precocious primitive streak gene activation when associated with CpG islands overlapping bivalent gene promotors. Moreover, hypermethylated regions amplify in numbers in the absence of TET1 through differentiation to affect genes associated with neurological functions. Our results reveal two-way safeguarding activities of TET1 separable by genomic features, where at CpG-poor distal enhancers TET1 maintains accessible chromatin permissive for neural fate independently of 5mC oxidation; at CpG-rich bivalent promoters it prevents premature gene activation inducing alternative fates by harnessing 5mC oxidation in Polycomb gene repression.