Project description:Previous work had established that Ezh2-deleted neural stem cells (NSCs) from the postnatal mouse subventricular zone (SVZ) had a deficit in both proliferation and neuronal differentiation both in vivo and in vitro. Ezh2-deleted NSCs in an Ink4a/Arf-deleted background proliferated normally but still displayed a neurogenesis defect, suggesting that Ezh2 is necessary for the proper expression of genes responsible for neuronal differentiation. Our results identify genes that are differentially regulated between control and Ezh2-deleted SVZ NSCs during differentiation. Total RNA obtained from SVZ NSCs 0, 1, 2, 4, and 7 days after switching from proliferation to differentiation media.
Project description:Previous work had established that Ezh2-deleted neural stem cells (NSCs) from the postnatal mouse subventricular zone (SVZ) had a deficit in both proliferation and neuronal differentiation both in vivo and in vitro. Ezh2-deleted NSCs in an Ink4a/Arf-deleted background proliferated normally but still displayed a neurogenesis defect, suggesting that Ezh2 is necessary for the proper expression of genes responsible for neuronal differentiation. Our results identify genes that are differentially regulated between control and Ezh2-deleted SVZ NSCs during differentiation.
Project description:The epigenetic mechanisms that enable specialized astrocytes to retain neurogenic competence throughout adult life are still poorly understood. Here we show that astrocytes that serve as neural stem cells (NSCs) in the adult mouse subventricular zone (SVZ) express the histone methyltransferase EZH2. This Polycomb repressive factor is required for neurogenesis independent of its role in SVZ NSC proliferation, as Ink4a/Arf-deficiency in Ezh2-deleted SVZ NSCs rescues cell proliferation, but neurogenesis remains defective. Olig2 is a direct target of EZH2, and repression of this bHLH transcription factor is critical for neuronal differentiation. Furthermore, Ezh2 prevents the inappropriate activation of genes that specify non-SVZ neuronal subtypes. In the human brain, SVZ cells including local astroglia also express EZH2, correlating with postnatal neurogenesis. Thus, EZH2 is an epigenetic regulator that distinguishes neurogenic SVZ astrocytes, orchestrating distinct and separable aspects of adult stem cell biology, which has important implications for regenerative medicine and oncogenesis. Examination of histone modifications (H3K27me3 and H3K4me3) in subventricular zone neural stem cells
Project description:The epigenetic mechanisms that enable specialized astrocytes to retain neurogenic competence throughout adult life are still poorly understood. Here we show that astrocytes that serve as neural stem cells (NSCs) in the adult mouse subventricular zone (SVZ) express the histone methyltransferase EZH2. This Polycomb repressive factor is required for neurogenesis independent of its role in SVZ NSC proliferation, as Ink4a/Arf-deficiency in Ezh2-deleted SVZ NSCs rescues cell proliferation, but neurogenesis remains defective. Olig2 is a direct target of EZH2, and repression of this bHLH transcription factor is critical for neuronal differentiation. Furthermore, Ezh2 prevents the inappropriate activation of genes that specify non-SVZ neuronal subtypes. In the human brain, SVZ cells including local astroglia also express EZH2, correlating with postnatal neurogenesis. Thus, EZH2 is an epigenetic regulator that distinguishes neurogenic SVZ astrocytes, orchestrating distinct and separable aspects of adult stem cell biology, which has important implications for regenerative medicine and oncogenesis.
Project description:BACKGROUND: The polycomb group protein Ezh2 is an epigenetic repressor of transcription originally found to prevent untimely differentiation of pluripotent embryonic stem cells. We previously demonstrated that Ezh2 is also expressed in multipotent neural stem cells (NSCs). We showed that Ezh2 expression is downregulated during NSC differentiation into astrocytes or neurons. However, high levels of Ezh2 remained present in differentiating oligodendrocytes until myelinating. This study aimed to elucidate the target genes of Ezh2 in NSCs and in premyelinating oligodendrocytes (pOLs). METHODOLOGY/PRINCIPAL FINDINGS: We performed chromatin immunoprecipitation followed by high-throughput sequencing to detect the target genes of Ezh2 in NSCs and pOLs. We found 1532 target genes of Ezh2 in NSCs. During NSC differentiation, the occupancy of these genes by Ezh2 was alleviated. However, when the NSCs differentiated into oligodendrocytes, 393 of these genes remained targets of Ezh2. Analysis of the target genes indicated that the repressive activity of Ezh2 in NSCs concerns genes involved in stem cell maintenance, in cell cycle control and in preventing neural differentiation. Among the genes in pOLs that were still repressed by Ezh2 were most prominently those associated with neuronal and astrocytic committed cell lineages. Suppression of Ezh2 activity in NSCs caused loss of stem cell characteristics, blocked their proliferation and ultimately induced apoptosis. Suppression of Ezh2 activity in pOLs resulted in derangement of the oligodendrocytic phenotype, due to re-expression of neuronal and astrocytic genes, and ultimately in apoptosis. CONCLUSIONS/SIGNIFICANCE: Our data indicate that the epigenetic repressor Ezh2 in NSCs is crucial for proliferative activity and maintenance of neural stemness. During differentiation towards oligodendrocytes, Ezh2 repression continues particularly to suppress other neural fate choices. Ezh2 is completely downregulated during differentiation towards neurons and astrocytes allowing transcription of these differentiation programs. The specific fate choice towards astrocytes or neurons is apparently controlled by epigenetic regulators other than Ezh2. Examination of Ezh2 target sites in 2 different primary cells types
Project description:Neural stem cells (NSCs) generate new neurons throughout life in two distinct areas of the mammalian brain: the subventricular zone (SVZ) lining the lateral ventricles and the hippocampal dentate gyrus (DG). How gene expression signatures differ among NSCs and immature neurons within and between these adult neurogenic regions is unknown. We isolated NSCs and their progeny using transgenic mice expressing GFP under the control of the Sox2 promoter (labeling NSCs) and transgenic mice expressing DsRed under the control of the doublecortin (Dcx) promoter (labeling immature neurons). Comparison of the transcriptomes of SOX2+ cells derived from both neurogenic areas revealed that NSCs are highly similar but that functionally significant differences in gene expression exist: IGF2, which is expressed only in SOX2+ cells in the DG but not in the SVZ, is required for proliferation of DG-derived but not SVZ-derived NSCs. Gene expression profiles strongly diverged in immature neurons, and we provide evidence that ephrinB3, which was up-regulated only in the DG but not in the SVZ during neuronal differentiation, regulates the survival of newborn granule cells. Thus, the data provided here show that stem cell populations in the adult DG and SVZ are similar but have unique properties that manifest themselves later during neural differentiation, resulting in distinct neuronal populations Hippocampi and SVZ from 6 week old DCX-DsRed and Sox2-GFP Reporter mice were dissected and cell sorted using FACS. cDNA were generated and analysed using Agilent Platform.
Project description:Transcriptional profiling of mouse postnatal SVZ NSCs comparing WT NSCs with KO NSCs under proliferating/undifferentiated states as well as differentiating conditions. Goal was to determine Dnmt3a-dependent gene expression changes in postnatal SVZ NSCs
Project description:BACKGROUND: The polycomb group protein Ezh2 is an epigenetic repressor of transcription originally found to prevent untimely differentiation of pluripotent embryonic stem cells. We previously demonstrated that Ezh2 is also expressed in multipotent neural stem cells (NSCs). We showed that Ezh2 expression is downregulated during NSC differentiation into astrocytes or neurons. However, high levels of Ezh2 remained present in differentiating oligodendrocytes until myelinating. This study aimed to elucidate the target genes of Ezh2 in NSCs and in premyelinating oligodendrocytes (pOLs). METHODOLOGY/PRINCIPAL FINDINGS: We performed chromatin immunoprecipitation followed by high-throughput sequencing to detect the target genes of Ezh2 in NSCs and pOLs. We found 1532 target genes of Ezh2 in NSCs. During NSC differentiation, the occupancy of these genes by Ezh2 was alleviated. However, when the NSCs differentiated into oligodendrocytes, 393 of these genes remained targets of Ezh2. Analysis of the target genes indicated that the repressive activity of Ezh2 in NSCs concerns genes involved in stem cell maintenance, in cell cycle control and in preventing neural differentiation. Among the genes in pOLs that were still repressed by Ezh2 were most prominently those associated with neuronal and astrocytic committed cell lineages. Suppression of Ezh2 activity in NSCs caused loss of stem cell characteristics, blocked their proliferation and ultimately induced apoptosis. Suppression of Ezh2 activity in pOLs resulted in derangement of the oligodendrocytic phenotype, due to re-expression of neuronal and astrocytic genes, and ultimately in apoptosis. CONCLUSIONS/SIGNIFICANCE: Our data indicate that the epigenetic repressor Ezh2 in NSCs is crucial for proliferative activity and maintenance of neural stemness. During differentiation towards oligodendrocytes, Ezh2 repression continues particularly to suppress other neural fate choices. Ezh2 is completely downregulated during differentiation towards neurons and astrocytes allowing transcription of these differentiation programs. The specific fate choice towards astrocytes or neurons is apparently controlled by epigenetic regulators other than Ezh2.
Project description:Transcriptional profiling of mouse postnatal SVZ NSCs comparing WT NSCs with KO NSCs under proliferating/undifferentiated states as well as differentiating conditions. Goal was to determine Dnmt3a-dependent gene expression changes in postnatal SVZ NSCs Two-condition experiment with a dye-swap design, WT NSCs vs. KO NSCs. Biological replicates: 4 replicates under proliferating/undifferentiation conditions, 2 replicates under differentiating conditions.