Project description:One of the most striking epigenetic alterations that occurs at the level of the nucleosome is the complete exchange of the canonical H2A histones for the macroH2A variant. Here, we provide insight in the function of this unique histone variant in embryonic and adult stem cells. Knockdown of macroH2A1 in mouse embryonic stem (mES) cells limited their capacity to differentiate but not their self-renewal. The loss of macroH2A1 interfered with the proper activation of differentiation genes, most of which are direct target genes of macroH2A. Additionally, macroH2A1-deficient mES cells displayed incomplete inactivation of pluripotency genes and formed defective embryoid bodies. In vivo, macroH2A1-deficient teratomas contained a massive expansion of malignant, undifferentiated carcinoma tissue. In the heterogeneous culture of primary human keratinocytes, macroH2A1 levels negatively correlated with the self-renewal capacity of the pluripotent compartment. Together these results establish macroH2A1 as a critical chromatin component that regulates the delicate balance between self-renewal and differentiation of embryonic and adult stem cells. Examination of the histone variant macroH2A1 in mouse Embryonic stem cells
Project description:One of the most striking epigenetic alterations that occurs at the level of the nucleosome is the complete exchange of the canonical H2A histones for the macroH2A variant. Here, we provide insight in the function of this unique histone variant in embryonic and adult stem cells. Knockdown of macroH2A1 in mouse embryonic stem (mES) cells limited their capacity to differentiate but not their self-renewal. The loss of macroH2A1 interfered with the proper activation of differentiation genes, most of which are direct target genes of macroH2A. Additionally, macroH2A1-deficient mES cells displayed incomplete inactivation of pluripotency genes and formed defective embryoid bodies. In vivo, macroH2A1-deficient teratomas contained a massive expansion of malignant, undifferentiated carcinoma tissue. In the heterogeneous culture of primary human keratinocytes, macroH2A1 levels negatively correlated with the self-renewal capacity of the pluripotent compartment. Together these results establish macroH2A1 as a critical chromatin component that regulates the delicate balance between self-renewal and differentiation of embryonic and adult stem cells.
Project description:Epidermal homeostasis depends on a balance between stem cell renewal and terminal differentiation. The transition between the two cell states,termed commitment, is poorly understood. Here we characterise commitment by integrating transcriptomic and proteomic data from disaggregated primary human keratinocytes held in suspension to induce differentiation. Cell detachment induces several protein phosphatases, five of which - DUSP6, PPTC7, PTPN1, PTPN13 and PPP3CA – promote differentiation by negatively regulating ERK MAPK and positively regulating AP1 transcription factors. Conversely, DUSP10 expression antagonises commitment. The phosphatases form a dynamic network of transient positive and negative interactions that change over time, with DUSP6 predominating at commitment. Boolean network modelling identifies a mandatory switch between two stable states (stem and differentiated) via an unstable (committed) state. Phosphatase expression is also spatially regulated in vivo and in vitro. We conclude that an auto-regulatory phosphatase network maintains epidermal homeostasis by controlling the onset and duration of commitment.
Project description:Hematopoietic stem cells (HSCs) must balance self-renewal and lineage differentiation to regenerate the hematopoietic system throughout life. HSCs exhibit lineage-associated gene expression that keeps them responsive to demands of mature blood production. However, it is not known whether this process, termed lineage priming, directly influences HSC self-renewal. We investigated the link between stemness and lineage priming by attenuating the early lymphoid transcription factor E47 through ID2 over-expression (OE). Transcriptional profiling of ID2 OE HSCs showed down regulation of B-cell factors including EBF1 and FOXO1 with a concomitant increase in stemness programs and myeloerythroid factors including CEBPA and GATA1. This resulted in myeloid commitment bias from the earliest stages of differentiation. HSC self-renewal was strongly affected by this lineage perturbation resulting in an 11-fold expansion of HSCs. Thus, early lymphoid transcription factors antagonize human HSC self-renewal, providing a direct link between differentiation program priming and the maintenance of stem cell self-renewal. Three independent lineage depleted CB samples were transduced with P-CTRL or P-ID2 and injected into 5 mice (30 mice total). From every group of 5 mice, human lin- cells were isolated and GFP+CD34+CD38-CD45RA- HSPCs were sorted by FACS.
Project description:Hematopoietic stem cells (HSCs) must balance self-renewal and lineage differentiation to regenerate the hematopoietic system throughout life. HSCs exhibit lineage-associated gene expression that keeps them responsive to demands of mature blood production. However, it is not known whether this process, termed lineage priming, directly influences HSC self-renewal. We investigated the link between stemness and lineage priming by attenuating the early lymphoid transcription factor E47 through ID2 over-expression (OE). Transcriptional profiling of ID2 OE HSCs showed down regulation of B-cell factors including EBF1 and FOXO1 with a concomitant increase in stemness programs and myeloerythroid factors including CEBPA and GATA1. This resulted in myeloid commitment bias from the earliest stages of differentiation. HSC self-renewal was strongly affected by this lineage perturbation resulting in an 11-fold expansion of HSCs. Thus, early lymphoid transcription factors antagonize human HSC self-renewal, providing a direct link between differentiation program priming and the maintenance of stem cell self-renewal.
Project description:We have used mouse embryonic stem cells (ESCs) as a model to study the signaling mechanisms that regulate self-renewal and commitment to differentiation. We hypothesized that genes critical to stem cell fate would be dynamically regulated at the initiation of commitment. Time course microarray analysis following initiation of commitment led us to propose a model of ESC maintenance in which highly regulated transcription factors and chromatin remodeling genes (down-regulated in our time course) maintain repression of genes responsible for cell differentiation, morphogenesis and development (up-regulated in our time course). Microarrays of Oct4, Nanog and Sox2 shRNA knockdown cell lines confirmed predicted regulation of target genes. shRNA knockdowns of candidate genes were tested in a novel high throughput screen of self-renewal, confirming their role in ESC pluripotency. We have identified genes that are critical for self-renewal and those that initiate commitment and developed draft transcriptional networks that control self-renewal and early development. Keywords: genetic modification Gene expression in Oct4 knockdown, Sox2 knockdown and their empty vector contol ES cells was analyzed.
Project description:The Nucleosome Remodeling and Deacetylase (NuRD) complex plays an important role in gene expression regulation, stem cell self-renewal, and lineage commitment. Yet little is known about the dynamics of NuRD during cellular differentiation. Here, we study these dynamics using genome-wide profiling and quantitative interaction proteomics in mouse embryonic stem cells (ESCs) and neural progenitor cells (NPCs). The genomic targets of NuRD are highly dynamic during differentiation, with most binding occurring at cell-type specific promoters and enhancers. We identify ZFP296 as a novel, ESC-specific NuRD interactor that also interacts with the SIN3A complex. ChIP-sequencing in Zfp296 knockout (KO) ESCs reveals decreased NuRD binding both genome-wide and at ZFP296 binding sites, although this has little effect on the transcriptome. Nevertheless, Zfp296 KO ESCs exhibit delayed induction of lineage-specific markers upon differentiation to embryoid bodies. In summary, we identify an ESC-specific NuRD interacting protein which regulates genome-wide NuRD binding and cellular differentiation.
Project description:Here we report that NONO, a nuclear para-speckle component, instead functions as a chromatin regulator in mESCs acting in the ERK signaling pathway to regulate the balance between ground state versus mESCs primed for differentiation. NONO loss increases a \u201cground-like\u201d population of mESCs favoring self-renewal and more resist to differentiation, partially mimicking the effects of 2i. Mechanistically, NONO and ERK mainly co-binds a subset of development related, bivalent genes. Importantly, NONO and ERK reciprocally regulate one another, i.e. NONO regulates ERK activation while ERK controls NONO chromatin association, forming a self-reinforcing feedback loop. Our findings thus reveal a cell intrinsic mechanism involving NONO and ERK, which impact the balance between self-renewal and differentiation, respectively.