| 1. |
- Marstrand, T. T., et al.
(författare)
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A conceptual framework for the identification of candidate drugs and drug targets in acute promyelocytic leukemia
- 2010
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 24:7, s. 1265-1275
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Tidskriftsartikel (refereegranskat)abstract
- Chromosomal translocations of transcription factors generating fusion proteins with aberrant transcriptional activity are common in acute leukemia. In acute promyelocytic leukemia (APL), the promyelocytic leukemia-retinoic-acid receptor alpha (PML-RARA) fusion protein, which emerges as a consequence of the t(15;17) translocation, acts as a transcriptional repressor that blocks neutrophil differentiation at the promyelocyte (PM) stage. In this study, we used publicly available microarray data sets and identified signatures of genes dysregulated in APL by comparison of gene expression profiles of APL cells and normal PMs representing the same stage of differentiation. We next subjected our identified APL signatures of dysregulated genes to a series of computational analyses leading to (i) the finding that APL cells show stem cell properties with respect to gene expression and transcriptional regulation, and (ii) the identification of candidate drugs and drug targets for therapeutic interventions. Significantly, our study provides a conceptual framework that can be applied to any subtype of AML and cancer in general to uncover novel information from published microarray data sets at low cost. In a broader perspective, our study provides strong evidence that genomic strategies might be used in a clinical setting to prospectively identify candidate drugs that subsequently are validated in vitro to define the most effective drug combination for individual cancer patients on a rational basis. Leukemia (2010) 24, 1265-1275; doi:10.1038/leu.2010.95; published online 27 May 2010
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| 2. |
- Wilhelmson, Anna S K, et al.
(författare)
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Testosterone is an endogenous regulator of BAFF and splenic B cell number
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Testosterone deficiency in men is associated with increased risk for autoimmunity and increased B cell numbers through unknown mechanisms. Here we show that testosterone regulates the cytokine BAFF, an essential survival factor for B cells. Male mice lacking the androgen receptor have increased splenic B cell numbers, serum BAFF levels and splenic Baff mRNA. Testosterone deficiency by castration causes expansion of BAFF-producing fibro-blastic reticular cells (FRCs) in spleen, which may be coupled to lower splenic noradrenaline levels in castrated males, as an alpha-adrenergic agonist decreases splenic FRC number in vitro. Antibody-mediated blockade of the BAFF receptor or treatment with the neurotoxin 6-hydroxydopamine revert the increased splenic B cell numbers induced by castration. Among healthy men, serum BAFF levels are higher in men with low testosterone. Our study uncovers a previously unrecognized regulation of BAFF by testosterone and raises important questions about BAFF in testosterone-mediated protection against autoimmunity.
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| 3. |
- Hasemann, Marie S., et al.
(författare)
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Phosphorylation of Serine 248 of C/EBP alpha Is Dispensable for Myelopoiesis but Its Disruption Leads to a Low Penetrant Myeloid Disorder with Long Latency
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Background: Transcription factors play a key role in lineage commitment and differentiation of stem cells into distinct mature cells. In hematopoiesis, they regulate lineage-specific gene expression in a stage-specific manner through various physical and functional interactions with regulatory proteins that are simultanously recruited and activated to ensure timely gene expression. The transcription factor CCAAT/enhancer binding protein alpha (C/EBP alpha) is such a factor and is essential for the development of granulocytic/monocytic cells. The activity of C/EBP alpha is regulated on several levels including gene expression, alternative translation, protein interactions and posttranslational modifications, such as phosphorylation. In particular, the phosphorylation of serine 248 of the transactivation domain has been shown to be of crucial importance for granulocytic differentiation of 32Dcl3 cells in vitro. Methodology/Principal Findings: Here, we use mouse genetics to investigate the significance of C/EBP alpha serine 248 in vivo through the construction and analysis of Cebpa(S248A/S248A) knock-in mice. Surprisingly, 8-week old Cebpa(S248A/S248A) mice display normal steady-state hematopoiesis including unaltered development of mature myeloid cells. However, over time some of the animals develop a hematopoietic disorder with accumulation of multipotent, megakaryocytic and erythroid progenitor cells and a mild impairment of differentiation along the granulocytic-monocytic lineage. Furthermore, BM cells from Cebpa(S248A/S248A) animals display a competitive advantage compared to wild type cells in a transplantation assay. Conclusions/Significance: Taken together, our data shows that the substitution of C/EBP alpha serine 248 to alanine favors the selection of the megakaryocytic/erythroid lineage over the monocytic/granulocytic compartment in old mice and suggests that S248 phosphorylation may be required to maintain proper hematopoietic homeostasis in response to changes in the wiring of cellular signalling networks. More broadly, the marked differences between the phenotype of the S248A variant in vivo and in vitro highlight the need to exert caution when extending in vitro phenotypes to the more appropriate in vivo context.
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| 4. |
- Kirstetter, Peggy, et al.
(författare)
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Modeling of C/EBP alpha mutant acute myeloid leukemia reveals a common expression signature of committed myeloid leukemia-initiating cells
- 2008
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Ingår i: Cancer Cell. - : Elsevier BV. - 1878-3686 .- 1535-6108. ; 13:4, s. 299-310
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in the CEBPA gene are present in 7%-10% of human patients with acute myeloid leukemia (AML). However, no genetic models exist that demonstrate their etiological relevance. To mimic the most common mutations affecting CEBPA-that is, those leading to loss of the 42 kDa C/EBP alpha isoform (p42) while retaining the 30kDa isoform (p30)-we modified the mouse Cebpa locus to express only p30. p30 supported the formation of granulocyte-macrophage progenitors. However, p42 was required for control of myeloid progenitor proliferation, and p42-deficient mice developed AML with complete penetrance. p42-deficient leukemia could be transferred by a Mac1(+)c-Kit(+) population that gave rise only to myeloid cells in recipient mice. Expression profiling of this population against normal Mac1(+)c-Kit(+) progenitors revealed a signature shared with MLL-AF9-transformed AML.
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| 5. |
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| 6. |
- Sondergaard, E., et al.
(författare)
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ERG Controls B Cell Development by Promoting Igh V-to-DJ Recombination
- 2019
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 29:9
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Tidskriftsartikel (refereegranskat)abstract
- B cell development depends on the coordinated expression and cooperation of several transcription factors. Here we show that the transcription factor ETS-related gene (ERG) is crucial for normal B cell development and that its deletion results in a substantial loss of bone marrow B cell progenitors and peripheral B cells, as well as a skewing of splenic B cell populations. We find that ERG-deficient B lineage cells exhibit an early developmental block at the pre-B cell stage and proliferate less. The cells fail to express the immunoglobulin heavy chain due to inefficient V-to-DJ recombination, and cells that undergo recombination display a strong bias against incorporation of distal V gene segments. Furthermore, antisense transcription at PAX5-activated intergenic repeat (PAIR) elements, located in the distal region of the Igh locus, depends on ERG. These findings show that ERG serves as a critical regulator of B cell development by ensuring efficient and balanced V-to-DJ recombination.
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| 7. |
- Willer, A, et al.
(författare)
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TGIF1 is a negative regulator of MLL-rearranged acute myeloid leukemia.
- 2015
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 29:5, s. 1018-1031
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Tidskriftsartikel (refereegranskat)abstract
- Members of the TALE (Three-amino acid loop extension) family of atypical homeodomain-containing transcription factors are important downstream effectors of oncogenic fusion proteins involving the mixed lineage leukemia (MLL) gene. A well-characterized member of this protein family is MEIS1, which orchestrates a transcriptional program required for the maintenance of MLL-rearranged acute myeloid leukemia (AML). TGIF1/TGIF2 are relatively uncharacterized TALE transcription factors, which in contrast to the remaining family, have been shown to act as transcriptional repressors. Given the general importance of this family in malignant haematopoiesis we therefore tested the potential function of TGIF1 in the maintenance of MLL-rearranged AML. Gene expression analysis of MLL-rearranged patient blasts demonstrated reduced TGIF1 levels and, in accordance, we find that forced expression of TGIF1 in MLL-AF9 transformed cells promoted differentiation and cell cycle exit in vitro, and delayed leukemic onset in vivo. Mechanistically, we show that TGIF1 interferes with a MEIS1-dependent transcriptional program by associating to MEIS1-bound regions in a competitive manner and that the MEIS1:TGIF1 ratio influence clinical outcome. Collectively, these findings demonstrate that TALE family members can act both positively and negatively on transcriptional programs responsible for leukemic maintenance and provide novel insights into regulatory gene expression circuitries in MLL-rearranged AML.Leukemia accepted article preview online, 28 October 2014. doi:10.1038/leu.2014.307.
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