Project description:Embryonic stem (ES) cells continuously decide whether to maintain pluripotency or differentiate. While exogenous LIF and BMP4 perpetuate a pluripotent state, less is known about factors initiating differentiation. We show that heparan sulfate (HS) proteoglycans are critical co-receptors for signals inducing ES cell differentiation. Genetic targeting of NDST1 and 2, two enzymes required for N-sulfation of proteoglycans, blocked differentiation. This phenotype was rescued by HS presented in trans or by soluble heparin. NaClO3-, which reduces sulfation of proteoglycans, potently blocked differentiation of wild type cells. Mechanistically, N-sulfation was identified to be critical for functional autocrine FGF4 signalling. Micro array analysis identified the pluripotency maintaining transcription factors Nanog, KLF2/4/8, Tbx3 and Tcf3 to be negatively regulated, whereas markers of differentiation such as Gbx2, Dnmt3b, FGF5 and Brachyury were induced by sulfation-dependent-FGFR signalling. We show that several of these genes are heterogeneously expressed in ES cells and targeting of heparan sulfation or FGFR-signalling facilitated a homogenous Nanog/KLF4/Tbx3 positive ES cell state. This finding suggests that the recently discovered heterogeneous state of ES cells is regulated by HS-dependent FGFR signalling. Similarly, culturing blastocysts with NaClO3- eliminated GATA6 positive primitive endoderm progenitors generating a homogenous Nanog positive inner cell mass. Functionally, reduction of sulfation robustly improved de novo ES cell derivation efficiency. We conclude that N-sulfated HS is required for FGF4 signalling to maintain ES cells primed for differentiation in a heterogeneous state. Inhibiting this pathway facilitates a more naïve ground state. Four groups with three biological replicates and a technical duplicate in each
Project description:Embryonic stem (ES) cells continuously decide whether to maintain pluripotency or differentiate. While exogenous LIF and BMP4 perpetuate a pluripotent state, less is known about factors initiating differentiation. We show that heparan sulfate (HS) proteoglycans are critical co-receptors for signals inducing ES cell differentiation. Genetic targeting of NDST1 and 2, two enzymes required for N-sulfation of proteoglycans, blocked differentiation. This phenotype was rescued by HS presented in trans or by soluble heparin. NaClO3-, which reduces sulfation of proteoglycans, potently blocked differentiation of wild type cells. Mechanistically, N-sulfation was identified to be critical for functional autocrine FGF4 signalling. Micro array analysis identified the pluripotency maintaining transcription factors Nanog, KLF2/4/8, Tbx3 and Tcf3 to be negatively regulated, whereas markers of differentiation such as Gbx2, Dnmt3b, FGF5 and Brachyury were induced by sulfation-dependent-FGFR signalling. We show that several of these genes are heterogeneously expressed in ES cells and targeting of heparan sulfation or FGFR-signalling facilitated a homogenous Nanog/KLF4/Tbx3 positive ES cell state. This finding suggests that the recently discovered heterogeneous state of ES cells is regulated by HS-dependent FGFR signalling. Similarly, culturing blastocysts with NaClO3- eliminated GATA6 positive primitive endoderm progenitors generating a homogenous Nanog positive inner cell mass. Functionally, reduction of sulfation robustly improved de novo ES cell derivation efficiency. We conclude that N-sulfated HS is required for FGF4 signalling to maintain ES cells primed for differentiation in a heterogeneous state. Inhibiting this pathway facilitates a more naïve ground state.
Project description:Embryonic stem cells (ESCs) can exist in at least two states that transcriptionally resemble different stages of embryonic development. Naïve ESCs resemble peri-implantation stages and primed ESCs the pre-gastrulation epiblast. In mouse, primed ESCs give rise to definitive endoderm in response to pathways downstream of Nodal and Wnt signalling. However, when these cytokines are applied to naïve ESCs, they differentiate to a cell type that approximates early primitive endoderm (PrE), the blastocyst stage progenitor layer that gives rise to the extra-embryonic endoderm. Here, we apply this context dependency to human ESCs, showing that these cytokines drive the differentiation of naïve pluripotent cells to generate extra-embryonic PrE, or hypoblast, and, as in mouse, expanded as an in vitro model for naïve extra-embryonic endoderm (nEnd) in defined conditions. Consistent with observations made in mouse, human PrE differentiation is dependent on FGF signalling in vitro, and we show, that by inhibiting FGF receptor signalling, we could simplify naïve pluripotent culture such that inhibitor requirements closer resembled those used in mouse. These nEnd cultures represent stable extra-embryonic endoderm, or human hypoblast, cell lines.
Project description:Embryonic stem cells (ESCs) can exist in at least two states that transcriptionally resemble different stages of embryonic development. Naïve ESCs resemble peri-implantation stages and primed ESCs the pre-gastrulation epiblast. In mouse, primed ESCs give rise to definitive endoderm in response to pathways downstream of Nodal and Wnt signalling. However, when these cytokines are applied to naïve ESCs, they differentiate to a cell type that approximates early primitive endoderm (PrE), the blastocyst stage progenitor layer that gives rise to the extra-embryonic endoderm. Here, we apply this context dependency to human ESCs, showing that these cytokines drive the differentiation of naïve pluripotent cells to generate extra-embryonic PrE, or hypoblast, and, as in mouse, expanded as an in vitro model for naïve extra-embryonic endoderm (nEnd) in defined conditions. Consistent with observations made in mouse, human PrE differentiation is dependent on FGF signalling in vitro, and we show, that by inhibiting FGF receptor signalling, we could simplify naïve pluripotent culture such that inhibitor requirements closer resembled those used in mouse. These nEnd cultures represent stable extra-embryonic endoderm, or human hypoblast, cell lines.
Project description:We report AICDA facilitates naïve pluripotency of mouse iPSCs by suppressing FGF/ERK signaling. In the absence of AICDA iPSCs fail to achive naïve pluripotent state and display chracteristics of EpiSCs and are primed for differentiation.
Project description:We report AICDA facilitates naïve pluripotency of mouse iPSCs by suppressing FGF/ERK signaling. In the absence of AICDA iPSCs fail to achive naïve pluripotent state and display chracteristics of EpiSCs and are primed for differentiation.
Project description:Esrrb is a transcription factor implicated in embryonic stem (ES) cell self-renewal, yet its knockout causes intrauterine lethality due to defects in trophoblast development. Here we show that in trophoblast stem (TS) cells, Esrrb is a downstream target of fibroblast growth factor (Fgf) signalling and is critical to drive TS cell self-renewal. In contrast to its occupancy of pluripotency-associated loci in ES cells, Esrrb sustains the stemness of TS cells by direct binding and regulation of TS cell-specific transcription factors including Elf5 and Eomes. To elucidate the mechanisms whereby Esrrb controls the expression of its targets, we characterized its TS cell-specific interactome by mass spectrometry. Unlike in ES cells, Esrrb interacts in TS cells with the histone demethylase Lsd1 and with the RNA Polymerase II-associated Integrator complex. Our findings provide new insights into both, the general and context-dependent wiring of transcription factor networks in stem cells by master transcription factors.
Project description:For a short period of time in mammalian neonates, the mammalian heart can regenerate via cardiomyocyte proliferation. This regenerative capacity is largely absent in adults. In other organisms, including zebrafish, damaged hearts can regenerate throughout their lifespans. Many studies have been performed to understand the mechanisms of cardiomyocyte de-differentiation and proliferation during heart regeneration however, the underlying reason why adult zebrafish and young mammalian cardiomyocytes are primed to enter cell cycle have not been identified. Here we show the primed state of a pro-regenerative cardiomyocyte is dictated by its amino acid profile and metabolic state. Adult zebrafish cardiomyocyte regeneration is a result of amino acid-primed mTOR activation. Zebrafish and neonatal mouse cardiomyocytes display elevated glutamine levels, predisposing them to amino acid-driven activation of mTORC1. Injury initiates Wnt/β-catenin signalling that instigates primed mTORC1 activation, Lin28 expression and metabolic remodeling necessary for zebrafish cardiomyocyte regeneration. These studies reveal a unique mTORC1 primed state in zebrafish and mammalian regeneration competent cardiomyocytes.
Project description:Mouse embryonic stem (ES) cells are isolated from the inner cell mass of blastocysts, and can be preserved in vitro in a naive inner-cell-mass-like configuration by providing exogenous stimulation with leukaemia inhibitory factor (LIF) and small molecule inhibition of ERK1/ERK2 and GSK3b signalling (termed 2i/LIF conditions). Hallmarks of naive pluripotency include driving Oct4 (also known as Pou5f1) transcription by its distal enhancer, retaining a pre-inactivation X chromosome state, global reduction in DNA methylation and in H3K27me3 repressive chromatin mark deposition on developmental regulatory gene promoters.Upon withdrawal of 2i/LIF, naM-CM-/ve mouse ES cells can drift towards a primed pluripotent state resembling that of the post-implantation epiblast. Although human ES cells share several molecular features with naive mouse ES cells, they also share a variety of epigenetic properties with primed murine epiblast stem cells (EpiSCs). These include use of the proximal enhancer element to maintain OCT4 expression, pronounced tendency for X chromosome inactivation in most female human ES cells, increase in DNA methylation and prominent deposition of H3K27me3 and bivalency acquisition on lineage regulatory genes. The feasibility for establishing human ground state naive pluripotency in vitro with equivalent molecular and functional features to those characterized in rodent ES cells remains to be defined. Here we establish defined conditions that facilitate the derivation of genetically unmodified human naive pluripotent stem cells from already established primed human ES cells, from somatic cells through induced pluripotent stem (iPS) cell reprogramming or directly from blastocysts. The novel naive pluripotent cells validated herein retain molecular characteristics and functional properties that are highly similar to mouse naive ES cells, and distinct from conventional primed human pluripotent cells. This includes competence in the generation of cross-species chimaeric embryos that underwent organogenesis following microinjection of human naive iPS cells into mouse morulas. Collectively, our findings establish new avenues for regenerative medicine, patient-specific iPS cell disease modelling and the study of early human development in vitro and in vivo. Total of 12 samples of naM-CM-/ve and primed human ESC lines were analyzed for gene expression. Many of the lines analyzed are genetically matched (H9, WIBR3).