| 1. |
- Hansson, Anders, et al.
(författare)
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The Lim-only protein LMO2 acts as a positive regulator of erythroid differentiation
- 2007
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 364:3, s. 675-681
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Tidskriftsartikel (refereegranskat)abstract
- LMO2, a member of the LIM-only protein family, is essential for the regulation of hematopoietic stem cells and formation of erythroid cells. It is found in a transcriptional complex comprising LMO2, TAL1, E47, GATA-1, and LDB1 which regulates erythroid genes. While TAL1 has been shown to induce erythroid differentiation, LMO2 appears to suppress fetal erythropoiesis. In addition to LMO2, the closely related LMO4 gene is expressed in hematopoietic cells, but has unknown functions. Here we demonstrate that LMO2 and LMO4 are expressed at the same level in erythroid colonies from mouse bone marrow, implying a function in erythroid differentiation. However, while LMO2 induced erythroid differentiation, LMO4 had no such effect. Interestingly, both LMO2 and TAL1 were able to partially suppress myeloid differentiation, implying that they activate erythroid differentiation in uncommitted bone marrow progenitors. Both LMO2 and LMO4 interacted strongly to LDB1, which was required for their localization to the nucleus. © 2007 Elsevier Inc. All rights reserved.
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| 2. |
- Lagergren, Anna, et al.
(författare)
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The Cxcl12, Periostin, and Ccl9 genes are direct targets for early B-cell factor in OP-9 stroma cells
- 2007
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 282:19, s. 14454-14462
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Tidskriftsartikel (refereegranskat)abstract
- The development of blood cells from hematopoietic stem cells in the bone marrow is dependent on communication with bone marrow stroma cells, making these cells central for the appropriate regulation of hematopoiesis. To identify transcription factors that may play a role in gene regulation in stroma cells, we performed comparative gene expression analysis of fibroblastic NIH3T3 cells, unable to support hematopoiesis in vitro, and OP-9 stroma cells, highly efficient in this regard. These experiments revealed that transcription factors of the early B cell factor (EBF) family were highly expressed in OP-9 cells as compared with the NIH3T3 cells. To identify potential targets genes for EBF proteins in stroma cells, we overexpressed EBF in fibroblasts and analyzed the pattern of induced genes by microarray analysis. This revealed that EBF was able to up-regulate expression of among others the Cxcl12, Ccl9, and Periostin genes. The identification of relevant promoters revealed that they all contained functional EBF binding sites able to interact with EBF in OP-9 cells. Furthermore, ectopic expression of a dominant negative EBF protein or antisense EBF-1 RNA in OP-9 stroma cells resulted in reduced expression of these target genes. These data suggest that EBF proteins might have dual roles in hematopoiesis acting both as intrinsic regulators of B-lymphopoiesis and as regulators of genes in bone marrow stroma cells. © 2007 by The American Society for Biochemistry and Molecular Biology, Inc.
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| 3. |
- Nordigården, Amanda, et al.
(författare)
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Irreversible pan-ERBB inhibitor canertinib elicits anti-leukaemic effects and induces the regression of FLT3-ITD transformed cells in mice
- 2011
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Ingår i: British Journal of Haematology. - : Blackwell Publishing. - 0007-1048 .- 1365-2141. ; 155:2, s. 198-208
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Tidskriftsartikel (refereegranskat)abstract
- Recent findings have indicated that tyrosine kinase inhibitors (TKIs) targeting the ERBB receptor family display anti-leukaemic effects, despite the lack of receptor expression on human leukaemic cells. The occurrence of activating mutations in the gene encoding FMS-like tyrosine kinase 3 (FLT3) in patients with acute myeloid leukaemia (AML) has rendered inhibition of this receptor a promising therapeutic target. Due to possibility of cross-reactivity, we investigated the effect of the irreversible pan-ERBB inhibitor canertinib (CI-1033) on leukaemic cells expressing FLT3. The drug had anti-proliferative and apoptotic effects on primary AML cells and human leukaemic cell lines expressing mutated FLT3. In several AML patient samples, a blast cell population expressing FLT3-internal tandem duplication (ITD) was eradicated by canertinib. Canertinib inhibited receptor autophosphorylation and kinase activity of both mutated and FLT3 ligand stimulated wildtype FLT3, leading to inhibition of the PI3-kinase and MAP kinase pathways. Apoptotic induction was dependent on pro-apoptotic BH3-only protein BCL2L11/BIM because siRNA silencing attenuated apoptosis. Moreover, the drug induced regression of cells expressing FLT3-ITD in a murine in vivo-transplantation model at previously described tolerated doses. These results indicate that canertinib, as an irreversible TKI, could constitute a novel treatment regimen in patients with mutated or overexpressed FLT3.
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| 4. |
- Stjernberg (Zetterblad), Jenny
(författare)
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Knock Knock Knock, Who is there? - Cell Crosstalk within the Bone Marrow
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is focused on the subject of cell-cell interaction. Our body is composed of cells, most of them are integrated in a network with other cells that together forms tissues and organs. Every cell type in these complex organs has its special task and location. This is true whether we are doing research on humans or, as we have been, investigating mice. Mice are excellent models for studies of blood cell development since this process in mice resembles human blood cell generation in many regards.Cells communicate with each other by sending out small molecules or by directly binding to surrounding cells; to cells of the same kind as well as to cells with different origins and tasks. A cell is surrounded by hundreds of different signal-carrying entities; soluble, bound to the extra cellular matrix or bound to its surface. Every cell has to distinguish and respond to the environment according to its own specific nature.In the first article interleukin 7 (IL-7) a growth factor expressed by the stroma cells was studied. Results show that IL-7 is crucial for the immature progenitor cell in its development towards antibody producing B-lymphocytes. The second article is about stroma cells and their ability to support the development of B-cells. It is a comparative study on two different cell lines, where we focus on transcription factors and their regulation of protein induction of factors supporting B-cells. This study increased our knowledge of stroma cells. In the third paper we combined our knowledge from the first two papers in regard to stroma cells as well as B-cell development by testing if there is a possibility to theoretically find new factors of importance for the maturing B-cell. We achieved this by the development of GCINT, a database investigating possible receptorligand interactions between two cells, verifying these results in vitro with cell lines as well as primary cells. This revealed a two way communication between blood cells and stroma cells, highlighting the complexity of the bone marrow environment. In the last article we continued this work with primary FACS sorted stroma cells investing the potential connections between each of the stroma cell populations with primary blood cells in different stages of development. This work supports a model where hematopoietic cells can interact with stroma cells in a stage-specific manner and that the exchange between cells is of importance for their maturation.
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| 5. |
- Tsapogas, Panagiotis, et al.
(författare)
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IL-7 mediates Ebf-1-dependent lineage restriction in early lymphoid progenitors
- 2011
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 118:5, s. 1283-1290
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Tidskriftsartikel (refereegranskat)abstract
- eficiencies in the IL-7 signaling pathway result in severe disruptions of lymphoid development in adult mice. To understand more about how IL-7 deficiency impacts early lymphoid development, we have investigated lineage restriction events within the common lymphoid progenitor (CLP) compartment in IL-7 knockout mice. This revealed that although IL-7 deficiency had a minor impact on the development of LY6D(-) multipotent CLPs, the formation of the lineage restricted LY6D(+) CLP population was dramatically reduced. This was reflected in a low-level transcription of B-lineage genes as well as in a loss of functional B-cell commitment. The few Ly6D(+) CLPs developed in the absence of IL-7 displayed increased lineage plasticity and low expression of Ebf-1. Absence of Ebf-1 could be linked to increased plasticity because even though Ly6D(+) cells develop in Ebf-1-deficient mice, these cells retain both natural killer and dendritic cell potential. This reveals that IL-7 is essential for normal development of Ly6D(+) CLPs and that Ebf-1 is crucial for lineage restriction in early lymphoid progenitors.
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| 6. |
- Zandi, Sasan, 1976-, et al.
(författare)
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EBF1 is essential for B-lineage priming and establishment of a transcription factor network in common lymphoid progenitors
- 2008
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Ingår i: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 181:5, s. 3364-3372
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Tidskriftsartikel (refereegranskat)abstract
- Development of B-lymphoid cells in the bone marrow is a process under strict control of a hierarchy of transcription factors. To understand the development of a B-lymphoid-restricted functional network of transcription factors, we have investigated the cell autonomous role of the transcription factor EBF1 in early B cell development. This revealed that even though transplanted EBF1-deficient fetal liver cells were able to generate common lymphoid progenitors (CLPs) as well as B220(+)CD43(+)AA4.1(+) candidate precursor B cells, none of these populations showed signs of B lineage priming. The isolated CLPs were able to generate T lymphocytes in vitro supporting the idea that the phenotype of EBF1-deficient mice is restricted to the development of the B lineage. Furthermore, EBF deficient CLPs displayed a reduction in Ig H chain recombination as compared with their wild-type counterpart and essentially lacked transcription of B-lineage-associated genes. Among the genes displaying reduced expression in the EBF1 deficient CLPs were the transcription factors Pax5, Pou2af1 (OcaB), and FoxO1 that all appear to be direct genetic targets for EBF1 because their promoters contained functional binding sites for this factor. This leads us to suggest that EBF1 regulates a transcription factor network crucial for B lineage commitment.
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| 7. |
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| 8. |
- Zetterblad, Jenny, et al.
(författare)
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Genomics based analysis of interactions between developing B-lymphocytes and stromal cells reveal complex interactions and two-way communication
- 2010
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 11:108
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Tidskriftsartikel (refereegranskat)abstract
- Background: The use of functional genomics has largely increased our understanding of cell biology and promises to help the development of systems biology needed to understand the complex order of events that regulates cellular differentiation in vivo. One model system clearly dependent on the integration of extra and intra cellular signals is the development of B-lymphocytes from hematopoietic stem cells in the bone marrow. This developmental pathway involves several defined differentiation stages associated with specific expression of genes including surface markers that can be used for the prospective isolation of the progenitor cells directly from the bone marrow to allow for ex vivo gene expression analysis. The developmental process can be simulated in vitro making it possible to dissect information about cell/cell communication as well as to address the relevance of communication pathways in a rather direct manner. Thus we believe that B-lymphocyte development represents a useful model system to take the first steps towards systems biology investigations in the bone marrow. Results: In order to identify extra cellular signals that promote B lymphocyte development we created a database with approximately 400 receptor ligand pairs and software matching gene expression data from two cell populations to obtain information about possible communication pathways. Using this database and gene expression data from NIH3T3 cells (unable to support B cell development), OP-9 cells (strongly supportive of B cell development), pro-B and pre-B cells as well as mature peripheral B-lineage cells, we were able to identify a set of potential stage and stromal cell restricted communication pathways. Functional analysis of some of these potential ways of communication allowed us to identify BMP-4 as a potent stimulator of B-cell development in vitro. Further, the analysis suggested that there existed possibilities for progenitor B cells to send signals to the stroma. The functional consequences of this were investigated by co-culture experiments revealing that the co-incubation of stromal cells with B cell progenitors altered both the morphology and the gene expression pattern in the stromal cells. Conclusions: We believe that this gene expression data analysis method allows for the identification of functionally relevant interactions and therefore could be applied to other data sets to unravel novel communication pathways.
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| 9. |
- Åhsberg, Josefine, et al.
(författare)
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Interleukin-7-induced Stat-5 Acts in Synergy with Flt-3 Signaling to Stimulate Expansion of Hematopoietic Progenitor Cells
- 2010
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Ingår i: JOURNAL OF BIOLOGICAL CHEMISTRY. - : The American Society for Biochemistry and Molecular Biology. - 0021-9258. ; 285:47, s. 36275-36284
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Tidskriftsartikel (refereegranskat)abstract
- The development of lymphoid cells from bone marrow progenitors is dictated by interplay between internal cues such as transcription factors and external signals like the cytokines Flt-3 ligand and Il-7. These proteins are both of large importance for normal lymphoid development; however, it is unclear if they act in direct synergy to expand a transient Il-7R(+)Flt-3(+) population or if the collaboration is created through sequential activities. We report here that Flt-3L and Il-7 synergistically stimulated the expansion of primary Il-7R(+)Flt-3(+) progenitor cells and a hematopoietic progenitor cell line ectopically expressing the receptors. The stimulation resulted in a reduced expression of pro-apoptotic genes and also mediated survival of primary progenitor cells in vitro. However, functional analysis of single cells suggested that the anti-apoptotic effect was additive indicating that the synergy observed mainly depends on stimulation of proliferation. Analysis of downstream signaling events suggested that although Il-7 induced Stat-5 phosphorylation, Flt-3L caused activation of the ERK and AKT signaling pathways. Flt-3L could also drive proliferation in synergy with ectopically expressed constitutively active Stat-5. This synergy could be inhibited with either receptor tyrosine kinase or MAPK inhibitors suggesting that Flt-3L and Il-7 act in synergy by activation of independent signaling pathways to expand early hematopoietic progenitors.
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