Loss of Ezh2 promotes a midbrain-to-forebrain identity switch by direct gene derepression and Wnt-dependent regulation
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE74538 | GEO | 2015/11/09
SECONDARY ACCESSION(S): PRJNA300674
REPOSITORIES: GEO
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Project description:Background: Precise spatiotemporal control of gene expression is essential for the establishment of correct cell numbers and identities during brain development. This process involves epigenetic control mechanisms, such as those mediated by the polycomb group protein Ezh2 that catalyzes trimethylation of histone H3K27 (H3K27me3) and thereby represses gene expression. Results: Here we show that Ezh2 plays a crucial role in development and maintenance of the midbrain. Conditional deletion of Ezh2 in the developing midbrain resulted in decreased neural progenitor proliferation, which is associated with derepression of cell cycle inhibitors and negative regulation of Wnt/beta-catenin signaling. Of note, Ezh2 ablation also promoted ectopic expression of a forebrain transcriptional program involving derepression of the forebrain determinants Foxg1 and Pax6. This was accompanied by reduced expression of midbrain markers, including Pax3 and Pax7, as a consequence of decreased Wnt/beta-catenin signaling. Conclusion: Ezh2 is required for appropriate brain growth and for maintenance of regional identity by H3K27me3-mediated gene repression and control of canonical Wnt signaling. After tissue isolation from dorsal midbrains of embryonic day (E) 10.5 embryos, total RNA was isolated with the RNAeasy kit (Qiagen) and RNase-Free DNase Set (79254, Qiagen) following the manufacturer's instructions. Isolated total RNA of E10.5 control (n=3, from 2 different litters) and Ezh2 cko (n=3, from 2 different litters) dorsal midbrains was used for microarray analysis performed at the Functional Genomics Center Zurich (FGCZ), Switzerland, using the Affymetrix A430 platform.
2015-11-09 | E-GEOD-74538 | biostudies-arrayexpress
Project description:The Wnt/b-catenin signaling inhibits adipogenesis. Genome-wide profiling studies have revealed the enrichment of histone H3K27 methyltransferase PRC2 on Wnt genes. However, the functional significance of such a direct link between the two types of developmental regulators in mammalian cells, and the role of PRC2 in adipogenesis, remain unclear. Here we show PRC2 and its H3K27 methyltransferase activity are required for adipogenesis. PRC2 directly represses Wnt1, 6, 10a and 10b genes in preadipocytes and during adipogenesis. Deletion of the enzymatic Ezh2 subunit of PRC2 eliminates H3K27me3 on Wnt promoters and de-represses Wnt expression, which leads to activation of Wnt/b-catenin signaling and inhibition of adipogenesis. Ectopic expression of the wild type Ezh2, but not the enzymatically inactive F667I mutant, prevents the loss of H3K27me3 and the defects in adipogenesis in Ezh2-/- preadipocytes. The adipogenesis defects in Ezh2-/- cells can be rescued by expression of adipogenic transcription factors PPARa, C/EBPb, or inhibitors of Wnt/b-catenin signaling. Interestingly, Ezh2-/- cells show marked increase of H3K27 acetylation globally as well as on Wnt promoters. These results indicate that H3K27 methyltransferase PRC2 directly represses Wnt genes to facilitate adipogenesis, and suggest that acetylation and trimethylation on H3K27 play opposing roles in regulating Wnt expression. To identify additional PRC2-regulated genes in preadipocytes, we performed microarray analysis in Ezh2flox/flox preadipocytes infected with retroviruses expressing Cre or vector alone.
2010-03-19 | E-GEOD-20054 | biostudies-arrayexpress
Project description:The Wnt/b-catenin signaling inhibits adipogenesis. Genome-wide profiling studies have revealed the enrichment of histone H3K27 methyltransferase PRC2 on Wnt genes. However, the functional significance of such a direct link between the two types of developmental regulators in mammalian cells, and the role of PRC2 in adipogenesis, remain unclear. Here we show PRC2 and its H3K27 methyltransferase activity are required for adipogenesis. PRC2 directly represses Wnt1, 6, 10a and 10b genes in preadipocytes and during adipogenesis. Deletion of the enzymatic Ezh2 subunit of PRC2 eliminates H3K27me3 on Wnt promoters and de-represses Wnt expression, which leads to activation of Wnt/b-catenin signaling and inhibition of adipogenesis. Ectopic expression of the wild type Ezh2, but not the enzymatically inactive F667I mutant, prevents the loss of H3K27me3 and the defects in adipogenesis in Ezh2-/- preadipocytes. The adipogenesis defects in Ezh2-/- cells can be rescued by expression of adipogenic transcription factors PPARa, C/EBPb, or inhibitors of Wnt/b-catenin signaling. Interestingly, Ezh2-/- cells show marked increase of H3K27 acetylation globally as well as on Wnt promoters. These results indicate that H3K27 methyltransferase PRC2 directly represses Wnt genes to facilitate adipogenesis, and suggest that acetylation and trimethylation on H3K27 play opposing roles in regulating Wnt expression.
2010-03-19 | GSE20054 | GEO
Project description:Loss of Ezh2 promotes a midbrain-to-forebrain identity switch by direct gene derepression and Wnt-dependent regulation
| PRJNA300674 | ENA
Project description:During mesenchymal stem cell (MSC) differentiation, both Wnt signaling and the development of a rigid cytoskeleton promote commitment to the osteoblastic over adipogenic lineage. β-catenin is thought to play a critical role in Wnt effects. We show that β-catenin was additive with cytoskeletal signals to prevent adipogenesis, and β-catenin knockdown promoted adipogenesis even when the actin cytoskeleton was depolymerized. β-catenin also prevented osteoblast commitment in a cytoskeletal-independent manner, with β-catenin knockdown enhancing lineage commitment. Chip-seq showed that β-catenin associated with the promoter of EZH2, a key component of the PRC2 complex that governs genome methylation. Knocking down β-catenin lowered EZH2 levels and H3K27me3 at osteogenic loci. Further, when EZH2 was inhibited, β-catenin ’s anti-differentiation effects were lost. These results indicate that regulating EZH2 activity is key to β-catenin effects on MSC to preserve MSC multipotentiality.
2019-10-17 | GSE138980 | GEO
Project description:The process that partitions the nascent vertebrate central nervous system into forebrain, midbrain, hindbrain, and spinal cord after neural induction is of fundamental interest in developmental biology, and is known to be dependent on Wnt/beta-catenin signaling at multiple steps. Neural induction specifies neural ectoderm with forebrain character that is subsequently posteriorized by graded Wnt signaling: embryological and mutant analyses have shown that progressively higher levels of Wnt signaling induce progressively more posterior fates. However, the mechanistic link between Wnt signaling and the molecular subdivision of the neural ectoderm into distinct domains in the anteroposterior (AP) axis is still not clear. To better understand how Wnt mediates neural AP patterning, we performed a temporal dissection of neural patterning in response to manipulations of Wnt signaling in zebrafish. We show that Wnt-mediated neural patterning in zebrafish can be divided into three phases: (I) a primary AP patterning phase, which occurs during gastrulation, (II) a mes/r1 (mesencephalon-rhombomere 1) specification and refinement phase, which occurs immediately after gastrulation, and (III) a midbrain-hindbrain boundary (MHB) morphogenesis phase, which occurs during segmentation stages. A major outcome of these Wnt signaling phases is the specification of the major compartment divisions of the developing brain: first the MHB, then the diencephalic-mesencephalic boundary (DMB). The specification of these lineage divisions depends upon the dynamic changes of gene transcription in response to Wnt signaling, which we show primarily involves transcriptional repression or indirect activation. We show that otx2b is directly repressed by Wnt signaling during primary AP patterning, but becomes resistant to Wnt-mediated repression during late gastrulation. Also during late gastrulation, Wnt signaling becomes both necessary and sufficient for expression of wnt8b, en2a, and her5 in mes/r1. We suggest that the change in otx2b response to Wnt regulation enables a transition to the mes/r1 phase of Wnt-mediated patterning, as it ensures that Wnts expressed in the midbrain and MHB do not suppress midbrain identity, and consequently reinforce formation of the DMB. These findings integrate important temporal elements into our spatial understanding of Wnt-mediated neural patterning and may serve as an important basis of a better understanding of neural patterning defects that have implications in human health.
2020-02-29 | GSE146124 | GEO
Project description:The Wnt/β-catenin signaling pathway is a critical regulator of development and stem cell maintenance. Mounting evidence suggests that the context-specific outcome of Wnt signaling is determined by the collaborative action of multiple transcription factors, including members of the highly conserved forkhead box (FOX) protein family. The contribution of FOX transcription factors to Wnt signaling has not been investigated in a systemic manner. Here, by combining β-catenin reporter assays with Wnt pathway-focused qPCR arrays and proximity proteomics of selected FOX family members, we determine that most FOX proteins are involved in the regulation of Wnt pathway activity and the expression of Wnt ligands and target genes. We conclude that FOX proteins are common regulators of the Wnt/β-catenin pathway that may control the outcome of Wnt signaling in a tissue-specific manner.
2023-04-19 | PXD038811 | Pride
Project description:The development of the mesodiencephalic dopaminergic (mdDA) neurons strongly depends on the WNT1/b-catenin signaling pathway. These neurons include the Substantia nigra pars compacta (SNc) subset that preferentially degenerates in Parkinson’s Disease (PD), and the ventral tegmental area (VTA) subpopulation implicated in a variety of neuropsychiatric disorders. The identity of the cells responding to this signaling pathway in the developing mammalian ventral midbrain (VM) and the precise mechanism of WNT/b-catenin action in these cells, however, are still unknown. Moreover, this signaling pathway has to be accurately balanced during mdDA neuron development: whereas low levels or absence of WNT1/b-catenin signaling abolish their correct specification, constitutive activation of this signaling pathway prevents their proper differentiation in the mouse. We show that the WNT/b-catenin-responsive cells constitute only a fraction of all mdDA progenitors, precursors and neurons in the murine VM. These WNT/b-catenin-responsive cells are mostly located in the Wnt1+, Rspo2+ and Lef1+ lateral floor plate of the medial and caudal midbrain, giving preferentially rise to caudomedial (VTA) mdDA neurons. Strong WNT/b-catenin signaling mediated by RSPO2, a WNT/b-catenin agonist, and LEF1, a nuclear effector of this pathway, inhibits the differentiation of WNT/b-catenin-responsive mdDA progenitors into mature mdDA neurons by repressing the murine Pitx3 gene via conserved LEF1/TCF binding sites in its promoter. Our data indicate that an attenuation of WNT/b-catenin signaling in mdDA progenitors is essential for their correct differentiation into specific mdDA neuron subsets, thus providing a new means for stem cell-based regenerative therapies of PD and in vitro models of neuropsychiatric diseases.
2020-09-02 | GSE99618 | GEO
Project description:Current ventral midbrain dopaminergic progenitor differentiation protocols utilize small molecule inhibitors targeting Glycogen synthase kinase-3 (GSK3) to activate Wnt signaling, a step required for the anterior-posterior patterning of the nervous system and acquisition of the midbrain fate. However, GSK3a and GSK3β are pleiotropic kinases involved in multiple signaling pathways and their inhibition is a known trigger of neurogenesis. We predicted that direct activation of specific Wnt receptors naturally involved during neural patterning would allow for a more precise spatiotemporal control of Wnt/β-catenin signaling and mimic endogenous cell-cell communication mechanisms to improve hPSC differentiation. Here, we characterized the expression of FZD receptors at the surface of neural progenitor cells with different regional identity. Our data shows that FZD5 expression is uniquely upregulated in anterior neural progenitors and is rapidly downregulated as cells adopt a posterior fate. This spatial regulation of Frizzled cell surface expression constitutes a novel regulatory mechanism adjusting the levels of β-catenin signaling along the anterior-posterior axis and possibly contribute to midbrain-hindbrain boundary formation. Using a tetravalent antibody that selectively triggers FZD5 and LRP6 clustering to activate Wnt/β-catenin signaling, we show that the resulting midbrain-patterned neural progenitors exhibit a gene expression program more closely aligned with the anatomical origin of dopaminergic neurons and could hence represent a more efficient source for cell transplant therapies.
2024-02-21 | GSE241042 | GEO
Project description:Current ventral midbrain dopaminergic progenitor differentiation protocols utilize small molecule inhibitors targeting Glycogen synthase kinase-3 (GSK3) to activate Wnt signaling, a step required for the anterior-posterior patterning of the nervous system and acquisition of the midbrain fate. However, GSK3a and GSK3β are pleiotropic kinases involved in multiple signaling pathways and their inhibition is a known trigger of neurogenesis. We predicted that direct activation of specific Wnt receptors naturally involved during neural patterning would allow for a more precise spatiotemporal control of Wnt/β-catenin signaling and mimic endogenous cell-cell communication mechanisms to improve hPSC differentiation. Here, we characterized the expression of FZD receptors at the surface of neural progenitor cells with different regional identity. Our data shows that FZD5 expression is uniquely upregulated in anterior neural progenitors and is rapidly downregulated as cells adopt a posterior fate. This spatial regulation of Frizzled cell surface expression constitutes a novel regulatory mechanism adjusting the levels of β-catenin signaling along the anterior-posterior axis and possibly contribute to midbrain-hindbrain boundary formation. Using a tetravalent antibody that selectively triggers FZD5 and LRP6 clustering to activate Wnt/β-catenin signaling, we show that the resulting midbrain-patterned neural progenitors exhibit a gene expression program more closely aligned with the anatomical origin of dopaminergic neurons and could hence represent a more efficient source for cell transplant therapies.
2024-02-21 | GSE241041 | GEO