Hematopoietic Stem Cell Differentiation Regulated by a Single Ubiquitin Ligase: Substrate Complex
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE19502 | GEO | 2010/03/01
SECONDARY ACCESSION(S): PRJNA122423
REPOSITORIES: GEO
Similar Datasets
Project description:Hematopoietic stem cell (HSC) differentiation is regulated by cell-intrinsic and extrinsic cues. In addition to transcriptional regulation, post-translational regulation may also control HSC differentiation. To test this hypothesis, we visualized ubiquitin-regulated protein stability of a single transcription factor, c-Myc. The stability of c-Myc protein was instructive of HSC quiescence and c-Myc protein abundance was controlled by the ubiquitin ligase Fbw7. Fine changes in stability of c-Myc protein regulated the HSC âgene expression signatureâ. Using whole genome genomic approaches, we identified specific regulators of HSC function that are directly controlled by c-Myc binding, however adult HSCs and embryonic stem cells sense and interpret distinctly c-Myc regulated gene expression. These studies show a ubiquitin ligaseâsubstrate pair can orchestrate the molecular program of HSC differentiation. Gene expression profiles from c-Myc-High and c-Myc-Low expressing Lineage negative, c-Kit and Sca1 positive (LSKs) were compared using genome wide mRNA expression profiling by Affymetrix genechip arrays (Mouse 430 2.0) and key targets were validated by chromatin immunoprecipitation experiments.
2010-03-07 | E-GEOD-19502 | biostudies-arrayexpress
Project description:Ubiquitination is a post-translational mechanism of control of diverse cellular processes. We focus here on the ubiquitin ligase Fbw7, a recently identified hematopoietic tumor suppressor that can target for degradation several important oncogenes including Notch1, c-Myc and cyclin E. We have generated conditional Fbw7 knock-out animals and inactivated the gene in hematopoietic stem cells (HSC) and their differentiated progeny. Deletion of Fbw7 specifically and rapidly affects the HSC compartment in a cell-autonomous manner. Fbw7-/- HSCs show defective maintenance of quiescence, leading to impaired self-renewal and a severe loss of competitive repopulating capacity. Furthermore, Fbw7-/- HSC are unable to colonize the thymus leading to a profound depletion of T cell progenitors. Deletion of Fbw7 in bone marrow stem cells and progenitors leads to the stabilization of c-Myc, a transcription factor previously implicated in HSC self-renewal. On the other hand, neither Notch1 nor cyclin E are stabilized in the bone marrow of Fbw7 deficient mice. Genome-wide transcriptome studies of Fbw7-/- HSC and hematopoietic progenitors indicate that Fbw7 controls, through the regulation of HSC cell cycle entry, the global transcriptional âsignatureâ that is associated with the quiescent, self-renewing HSC phenotype. Transcriptional consequences of inactivating Fbw7 in LKS cells. Experiment Overall Design: Four samples were analyzed: wild-type (WT) control and Fbw7-deficient (FBW7) Lin-ckit+Sca1+ (LSK) cells, as well as Lin-ckit+Sca1- myeloid progenitor (MP) cells, which served as a control for LSK-enriched/specific genes. Total bone marrow cells were pooled from three WT and three FBW7 mice before sorting LSK and MP populations.
2008-06-11 | E-GEOD-11178 | biostudies-arrayexpress
Project description:Ubiquitination is a post-translational mechanism of control of diverse cellular processes. We focus here on the ubiquitin ligase Fbw7, a recently identified hematopoietic tumor suppressor that can target for degradation several important oncogenes including Notch1, c-Myc and cyclin E. We have generated conditional Fbw7 knock-out animals and inactivated the gene in hematopoietic stem cells (HSC) and their differentiated progeny. Deletion of Fbw7 specifically and rapidly affects the HSC compartment in a cell-autonomous manner. Fbw7-/- HSCs show defective maintenance of quiescence, leading to impaired self-renewal and a severe loss of competitive repopulating capacity. Furthermore, Fbw7-/- HSC are unable to colonize the thymus leading to a profound depletion of T cell progenitors. Deletion of Fbw7 in bone marrow stem cells and progenitors leads to the stabilization of c-Myc, a transcription factor previously implicated in HSC self-renewal. On the other hand, neither Notch1 nor cyclin E are stabilized in the bone marrow of Fbw7 deficient mice. Genome-wide transcriptome studies of Fbw7-/- HSC and hematopoietic progenitors indicate that Fbw7 controls, through the regulation of HSC cell cycle entry, the global transcriptional “signature” that is associated with the quiescent, self-renewing HSC phenotype. Transcriptional consequences of inactivating Fbw7 in LKS cells. Keywords: cell type comparison
2008-04-15 | GSE11178 | GEO
Project description:The NOTCH signaling cascade, which is deregulated in T-cell acute lymphoblastic leukemia (T-ALL) and many other human cancers, offers an attractive target for molecular therapy. One approach employs gamma-secretase inhibitors (GSIs) to suppress production of the intracellular form of NOTCH (NICD), leading to cell growth arrest and apoptosis. Here we show that missense mutations or homozygous deletion of FBW7, which encodes a ubiquitin ligase that targets the NICD for destruction, mediate constitutive NICD expression. FBW7 mutations target key arginine residues needed for binding to the NICD. Although the mutant forms of Fbw7 still bind to MYC, they do not target MYC for degradation, suggesting that stabilization of both NICD and MYC may contribute to transformation in leukemias with mutations in FBW7. Leukemias with FBW7 mutations are resistant to the growth suppressive and apoptotic effects of the MRK-003 GSI. In some resistant lines that express the NICD, this resistance is accompanied by sustained mRNA levels of the NOTCH target DELTEX1 as well as MYC mRNA and protein, implying that residual NICD activity due to the mutant FBW7 can contribute to GSI resistance. Keywords: T-ALL, gamma-secretase, GSI, cell line comparison, FBW7 mutation
2007-08-06 | GSE8416 | GEO
Project description:We identified the ubiquitin ligase Huwe1 as a crucial regulator of hematopoietic stem cell (HSC) functions. We generated Huwe1 conditional knock-out mice and discovered that the loss of this ligase causes an increased proliferation and stem cell exhaustion, together with a decreased lymphoid specification in vivo. We observed that the ubiquitin ligase Huwe1 is controlling the expression of N-myc at the level of the most immature stem and progenitor hematopoietic populations, mediating the described effects. Hematopoietic stem cells (HSC) from the bone marrow of transgenic animals carrying a N-myc/mCherry fusion gene were sorted according to N-myc expression (defined by mCherry) into N-myc high and low subpopulations. Each of these 2 populations was subjected to microarray gene expression profiling.
2016-08-20 | E-GEOD-85832 | biostudies-arrayexpress
Project description:SOX9 is a master transcription factor that regulates development and stem cell programs. However, its potential oncogenic activity and regulatory mechanisms that control SOX9 protein stability are poorly understood. Here we show that SOX9 is a substrate of FBW7, a tumor suppressor and a SCF (Skp1-Cul1-F-box)-type ubiquitin ligase. FBW7 recognizes a conserved degron surrounding threonine 236 (T236) in SOX9 that is phosphorylated by GSK3 kinase. Specifically, FBW7-alpha targets T236-phosphorylated SOX9 for ubiquitylation and proteasomal degradation. Further, we demonstrate that FBW7 inactivation stabilizes SOX9 protein promoting migration, metastasis and treatment resistance in medulloblastoma, one of the most common childhood brain tumors. Notably, expression of mutationally stabilized SOX9-T236/240A in medulloblastoma cells coincides with activation of pro-metastatic genes. FBW7 is frequently downregulated in all medulloblastoma subgroups and mutated specifically in SHH-driven medulloblastoma. In cases where FBW7 mRNA levels are low, SOX9 protein is significantly elevated and this phenotype is associated with metastasis at diagnosis and poor patient outcome. Finally, pharmacological inhibition of PI3K/Akt/mTOR activity destabilizes SOX9 in a GSK3/FBW7-dependent manner, rendering medulloblastoma cells sensitive to cytostatic treatment.
2016-09-13 | GSE84320 | GEO
Project description:Fbw7, the substrate recognition subunit of SCF(Fbw7) ubiquitin ligase, mediates turnover of multiple proto-oncoproteins and promotes its own degradation. Fbw7-mediated substrate degradation is antagonized by the Usp28 deubiquitinase. We now show, using knockout mice, that Usp28 preferentially deubiquitinates and stabilizes Fbw7. Monoallelic deletion of Usp28 maintains stable Fbw7 but destabilizes Fbw7 substrates. In contrast, complete knockout of Usp28 promotes Pin1-dependent autocatalytic turnover of Fbw7, accumulation of Fbw7 substrates and oncogenic transformation. Overexpression of Usp28 stabilizes both Fbw7 and its substrates and similarly enhances transformation. We propose that dual regulation of Fbw7 activity by Usp28 maintains physiological levels of Fbw7 substrates, and that both loss and overexpression of Usp28 in human cancer promote Fbw7 substrate accumulation.
2015-05-01 | GSE59354 | GEO
Project description:The NOTCH signaling cascade, which is deregulated in T-cell acute lymphoblastic leukemia (T-ALL) and many other human cancers, offers an attractive target for molecular therapy. One approach employs gamma-secretase inhibitors (GSIs) to suppress production of the intracellular form of NOTCH (NICD), leading to cell growth arrest and apoptosis. Here we show that missense mutations or homozygous deletion of FBW7, which encodes a ubiquitin ligase that targets the NICD for destruction, mediate constitutive NICD expression. FBW7 mutations target key arginine residues needed for binding to the NICD. Although the mutant forms of Fbw7 still bind to MYC, they do not target MYC for degradation, suggesting that stabilization of both NICD and MYC may contribute to transformation in leukemias with mutations in FBW7. Leukemias with FBW7 mutations are resistant to the growth suppressive and apoptotic effects of the MRK-003 GSI. In some resistant lines that express the NICD, this resistance is accompanied by sustained mRNA levels of the NOTCH target DELTEX1 as well as MYC mRNA and protein, implying that residual NICD activity due to the mutant FBW7 can contribute to GSI resistance. Keywords: T-ALL, gamma-secretase, GSI, cell line comparison, FBW7 mutation Total RNA isolated from cultured cells was used to make fluorescently labeled cRNA that was hybridized to DNA oligonucleotide. Briefly, 4 µg of total RNA was used to synthesize dsDNA through reverse transcription. cRNA was produced by in vitro transcription and labeled postsynthetically with Cy3 or Cy5. Two populations of labeled cRNA, a reference population and an experimental population, were compared with each other by competitive hybridization to microarrays. Two hybridizations were done with each cRNA sample pair using a fluorescent dye reversal strategy. Human microarrays contained oligonucleotide probes corresponding to approximately 21,000 genes. All oligonucleotide probes on the microarrays were synthesized in situ with inkjet technology (Agilent Technologies, Palo Alto, CA). After hybridization, arrays were scanned and fluorescence intensities for each probe were recorded. Ratios of transcript abundance (experimental to control) were obtained following normalization and correction of the array intensity data. Gene expression data analysis was done with the Rosetta Resolver gene expression analysis software (version 6.0, Rosetta Biosoftware, Seattle, WA).
2010-05-27 | E-GEOD-8416 | biostudies-arrayexpress
Project description:Fbw7, the substrate recognition subunit of SCF(Fbw7) ubiquitin ligase, mediates turnover of multiple proto-oncoproteins and promotes its own degradation. Fbw7-mediated substrate degradation is antagonized by the Usp28 deubiquitinase. We now show, using knockout mice, that Usp28 preferentially deubiquitinates and stabilizes Fbw7. Monoallelic deletion of Usp28 maintains stable Fbw7 but destabilizes Fbw7 substrates. In contrast, complete knockout of Usp28 promotes Pin1-dependent autocatalytic turnover of Fbw7, accumulation of Fbw7 substrates and oncogenic transformation. Overexpression of Usp28 stabilizes both Fbw7 and its substrates and similarly enhances transformation. We propose that dual regulation of Fbw7 activity by Usp28 maintains physiological levels of Fbw7 substrates, and that both loss and overexpression of Usp28 in human cancer promote Fbw7 substrate accumulation. RNAseq experiments of E13.5 murine embryonic fibroblasts (MEFs) derived from animals in which Usp28 was either deleted (-/-), wildtype (+/+) or heterozygous (+/-). In a first set of experiments immortalized MEFs of all three genotypes were analysed in biological triplicates. In a second set of experiments immortalized and Ras transformed MEFs of all three genotypes and MEFs which overexpress USP28 (+/+/+) where sequenced in duplicates.
2015-05-01 | E-GEOD-59354 | biostudies-arrayexpress
Project description:We identified the ubiquitin ligase Huwe1 as a crucial regulator of hematopoietic stem cell (HSC) functions. We generated Huwe1 conditional knock-out mice and discovered that the loss of this ligase causes an increased proliferation and stem cell exhaustion, together with a decreased lymphoid specification in vivo. We observed that the ubiquitin ligase Huwe1 is controlling the expression of N-myc at the level of the most immature stem and progenitor hematopoietic populations, mediating the described effects.
2016-08-17 | GSE85723 | GEO