C/EBPα Is Required for Long-Term Self-Renewal and Lineage Priming of Hematopoietic Stem Cells and for the Maintenance of Epigenetic Configurations in Multipotent Progenitors

Hasemann, Marie Sigurd; Lauridsen, Felicia Kathrine Bratt; Waage, Johannes; Jakobsen, Janus Schou; Frank, Anne-Katrine; Schuster, Mikkel Bruhn; Rapin, Nicolas; Bagger, Frederik Otzen; Hoppe, Philipp S.; Schroeder, Timm; Porse, Bo T.

doi:10.1371/journal.pgen.1004079

Cited by 93 publications

(101 citation statements)

References 63 publications

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“…Recent studies show Mecom and Cebpa as part of the top 10% of genes that exhibit decreased and increased expression, respectively, during the transition from early stage, long term HSCs to lineage-committed progenitor cells (33), and Cebpa has a documented role in maintaining hematopoietic stem cells (15,18). Together, these published data and our data indicate that the function of EVI1 in maintaining HSCs may include maintaining Cebpa mRNA levels at a low level to prevent premature myeloid maturation (i.e.…”

Section: Discussionmentioning

confidence: 99%

EVI1 Interferes with Myeloid Maturation via Transcriptional Repression of Cebpa, via Binding to Two Far Downstream Regulatory Elements

Wilson

Tsakraklides

Tran

et al. 2016

Journal of Biological Chemistry

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One mechanism by which oncoproteins work is through perturbation of cellular maturation; understanding the mechanisms by which this occurs can lead to the development of targeted therapies. EVI1 is a zinc finger oncoprotein involved in the development of acute myeloid leukemia; previous work has shown it to interfere with the maturation of granulocytes from immature precursors. Here we investigate the mechanism by which that occurs, using an immortalized hematopoietic progenitor cell line, EML-C1, as a model system. We document that overexpression of EVI1 abrogates retinoic acid-induced maturation of EML cells into committed myeloid cells, a process that can be documented by the down-regulation of stem cell antigen-1 and acquisition of responsiveness to granulocyte-macrophage colony-stimulating factor. We show that this requires DNA binding capacity of EVI1, suggesting that downstream target genes are involved. We identify the myeloid regulator Cebpa as a target gene and identify two EVI1 binding regions within evolutionarily conserved enhancer elements at ؉35 and ؉37 kb relative to the gene. EVI1 can strongly suppress Cebpa transcription, and add-back of Cebpa into EVI1-expressing EML cells partially corrects the block in maturation. We identify the DNA sequences to which EVI1 binds at ؉35 and ؉37 kb and show that mutation of one of these releases Cebpa from EVI1-induced suppression. We observe a more complex picture in primary bone marrow cells, where EVI1 suppresses Cebpa in stem cells but not in more committed progenitors. Our data thus identify a regulatory node by which EVI1 contributes to leukemia, and this represents a possible therapeutic target for treatment of EVI1-expressing leukemia.

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Section: Discussionmentioning

confidence: 99%

EVI1 Interferes with Myeloid Maturation via Transcriptional Repression of Cebpa, via Binding to Two Far Downstream Regulatory Elements

Wilson

Tsakraklides

Tran

et al. 2016

Journal of Biological Chemistry

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“…For reciprocal transplantation, 3 × 10 6 Ly5. Hasemann et al (2014). Microarray data were normalized by RMA (robust multiarray analysis) followed by mean one-step probe set summarization using the Partek genomics suite 6.5 followed by analysis of differential expression between experimental groups (expression fold change >1.5; P < 0.05; q < 0.22, ANOVA F-test).…”

Section: Transplantation Assaysmentioning

confidence: 99%

“…Numerous studies in mice have identified factors that support self-renewal, including C/ EBPα, c-MYB, and SATb1 (Lieu and Reddy 2009;Will et al 2013;Hasemann et al 2014). Other factors, such as DNMT3a, shown to restrict self-renewal, are equally prevalent (Challen et al 2012).…”

mentioning

confidence: 99%

ERG promotes the maintenance of hematopoietic stem cells by restricting their differentiation

et al. 2015

Self Cite

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The balance between self-renewal and differentiation is crucial for the maintenance of hematopoietic stem cells (HSCs). Whereas numerous gene regulatory factors have been shown to control HSC self-renewal or drive their differentiation, we have relatively few insights into transcription factors that serve to restrict HSC differentiation. In the present work, we identify ETS (E-twenty-six)-related gene (ERG) as a critical factor protecting HSCs from differentiation. Specifically, loss of Erg accelerates HSC differentiation by >20-fold, thus leading to rapid depletion of immunophenotypic and functional HSCs. Molecularly, we could demonstrate that ERG, in addition to promoting the expression of HSC self-renewal genes, also represses a group of MYC targets, thereby explaining why Erg loss closely mimics Myc overexpression. Consistently, the BET domain inhibitor CPI-203, known to repress Myc expression, confers a partial phenotypic rescue. In summary, ERG plays a critical role in coordinating the balance between self-renewal and differentiation of HSCs.

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“…At the HSC stage, C/EBPα acts to prime HSCs for differentiation along the myeloid lineage via DNA binding to regulatory regions of genes induced during differentiation (16). Although conditional Cebpa knockout mice do not develop disease, the loss of Cebpa in adult HSCs leads to an increased number of functional and proliferative HSCs (15,17) and loss of HSC pool maintenance in serial transplantations (16). Cebpa expression is required for AML disease initiation by the oncogene MLL-ENL but not for disease maintenance (18).…”

Section: Introductionmentioning

confidence: 99%

The presence of C/EBPα and its degradation are both required for TRIB2-mediated leukaemia

et al. 2016

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C/EBPα (p42 and p30 isoforms) is commonly dysregulated in cancer via the action of oncogenes, and specifically in acute myeloid leukaemia (AML) by mutation. Elevated TRIB2 leads to the degradation of C/EBPα p42, leaving p30 intact in AML. Whether this relationship is a cooperative event in AML transformation is not known and the molecular mechanism involved remains elusive.Using mouse genetics our data reveal that in the complete absence of C/EBPα TRIB2 was unable to induce AML. Only in the presence of C/EBPα p42 and p30 were TRIB2 and p30 able to cooperate to decrease the latency of disease. We demonstrate the molecular mechanism involved in degradation of C/EBPα p42 requires site-specific direct interaction between TRIB2 and C/EBPα p42 for the K48-specific ubiquitin-dependent proteasomal degradation of C/EBPα p42. This interaction and ubiquitination is dependent on a critical C-terminal lysine residue on C/EBPα. We show effective targeting of this pathway pharmacologically using proteasome inhibitors in TRIB2 positive AML cells. Together, our data show that excess p30 cooperated with TRIB2 only in the presence of p42 to accelerate AML and the direct interaction and degradation of C/EBPα p42 is required for TRIB2-mediated AML.

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C/EBPα Is Required for Long-Term Self-Renewal and Lineage Priming of Hematopoietic Stem Cells and for the Maintenance of Epigenetic Configurations in Multipotent Progenitors

Cited by 93 publications

References 63 publications

EVI1 Interferes with Myeloid Maturation via Transcriptional Repression of Cebpa, via Binding to Two Far Downstream Regulatory Elements

EVI1 Interferes with Myeloid Maturation via Transcriptional Repression of Cebpa, via Binding to Two Far Downstream Regulatory Elements

ERG promotes the maintenance of hematopoietic stem cells by restricting their differentiation

The presence of C/EBPα and its degradation are both required for TRIB2-mediated leukaemia

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