| 1. |
- Blank Savukinas, Ulrika, et al.
(författare)
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Smad7 promotes self-renewal of hematopoietic stem cells in vivo.
- 2006
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 108:13, s. 4246-4254
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Tidskriftsartikel (refereegranskat)abstract
- The Smad-signaling pathway downstream of the transforming growth factor–beta superfamily of ligands is an evolutionarily conserved signaling circuitry with critical functions in a wide variety of biologic processes. To investigate the role of this pathway in the regulation of hematopoietic stem cells (HSCs), we have blocked Smad signaling by retroviral gene transfer of the inhibitory Smad7 to murine HSCs. We report here that the self-renewal capacity of HSCs is promoted in vivo upon blocking of the entire Smad pathway, as shown by both primary and secondary bone marrow (BM) transplantations. Importantly, HSCs overexpressing Smad7 have an unperturbed differentiation capacity as evidenced by normal contribution to both lymphoid and myeloid cell lineages, suggesting that the Smad pathway regulates self-renewal independently of differentiation. Moreover, phosphorylation of Smads was inhibited in response to ligand stimulation in BM cells, thus verifying impairment of the Smad-signaling cascade in Smad7-overexpressing cells. Taken together, these data reveal an important and previously unappreciated role for the Smad-signaling pathway in the regulation of self-renewal of HSCs in vivo.
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| 2. |
- Capellera-Garcia, Sandra, et al.
(författare)
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Defining the Minimal Factors Required for Erythropoiesis through Direct Lineage Conversion
- 2016
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 15:11, s. 2550-2562
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Tidskriftsartikel (refereegranskat)abstract
- Erythroid cell commitment and differentiation proceed through activation of a lineage-restricted transcriptional network orchestrated by a group of well characterized genes. However, the minimal set of factors necessary for instructing red blood cell (RBC) development remains undefined. We employed a screen for transcription factors allowing direct lineage reprograming from fibroblasts to induced erythroid progenitors/precursors (iEPs). We show that Gata1, Tal1, Lmo2, and c-Myc (GTLM) can rapidly convert murine and human fibroblasts directly to iEPs. The transcriptional signature of murine iEPs resembled mainly that of primitive erythroid progenitors in the yolk sac, whereas addition of Klf1 or Myb to the GTLM cocktail resulted in iEPs with a more adult-type globin expression pattern. Our results demonstrate that direct lineage conversion is a suitable platform for defining and studying the core factors inducing the different waves of erythroid development.
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| 3. |
- Chalk, Alistair M, et al.
(författare)
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Gene expression profiling to define the cell intrinsic role of the SKI proto-oncogene in hematopoiesis and myeloid neoplasms.
- 2014
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Ingår i: Genomics Data. - : Elsevier BV. - 2213-5960. ; 2, s. 189-191
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Tidskriftsartikel (refereegranskat)abstract
- The proto-oncogene SKI is highly expressed in human myeloid leukemia and also in murine hematopoietic stem cells. However, its operative relevance in these cells remains elusive. We have over-expressed SKI to define its intrinsic role in hematopoiesis and myeloid neoplasms, which resulted in a robust competitive advantage upon transplantation, a complete dominance of the stem and progenitor compartments, and a marked enhancement of myeloid differentiation at the expense of other lineages. Accordingly, enforced expression of SKI induced gene signatures associated with hematopoietic stem cells and myeloid differentiation. Here we provide detailed experimental methods and analysis for the gene expression profiling described in our recently published study of Singbrant et al. (2014) in Haematologica. Our data sets (available at http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE39457) provide a resource for exploring the underlying molecular mechanisms of the involvement of the proto-oncogene SKI in hematopoietic stem cell function and development of myeloid neoplasms.
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| 4. |
- Gundry, Michael C., et al.
(författare)
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Technical considerations for the use of CRISPR/Cas9 in hematology research
- 2017
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Ingår i: Experimental Hematology. - : Elsevier BV. - 0301-472X.
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Tidskriftsartikel (refereegranskat)abstract
- The hematopoietic system is responsible for transporting oxygen and nutrients, fighting infections, and repairing tissue damage. Hematopoietic system dysfunction therefore causes a range of serious health consequences. Lifelong hematopoiesis is maintained by repopulating multipotent hematopoietic stem cells (HSCs) that replenish shorter-lived, mature blood cell types. A prokaryotic mechanism of immunity, the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 nuclease system, has been recently "repurposed" to mutate mammalian genomes efficiently and in a sequence-specific manner. The application of this genome-editing technology to hematology has afforded new approaches for functional genomics and even the prospect of "correcting" dysfunctional HSCs in the treatment of serious genetic hematological diseases. In this Perspective, we provide an overview of three recent CRISPR/Cas9 methods in hematology: gene disruption, gene targeting, and saturating mutagenesis. We also summarize the technical considerations and advice provided during the May 2017 International Society of Experimental Hematology New Investigator Committee webinar on the same topic.
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| 5. |
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| 6. |
- Karlsson, Göran, et al.
(författare)
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Smad4 is critical for self-renewal of hematopoietic stem cells.
- 2007
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Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 204:3, s. 467-474
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Tidskriftsartikel (refereegranskat)abstract
- Members of the transforming growth factor β (TGF-β) superfamily of growth factors have been shown to regulate the in vitro proliferation and maintenance of hematopoietic stem cells (HSCs). Working at a common level of convergence for all TGF-β superfamily signals, Smad4 is key in orchestrating these effects. The role of Smad4 in HSC function has remained elusive because of the early embryonic lethality of the conventional knockout. We clarify its role by using an inducible model of Smad4 deletion coupled with transplantation experiments. Remarkably, systemic induction of Smad4 deletion through activation of MxCre was incompatible with survival 4 wk after induction because of anemia and histopathological changes in the colonic mucosa. Isolation of Smad4 deletion to the hematopoietic system via several transplantation approaches demonstrated a role for Smad4 in the maintenance of HSC self-renewal and reconstituting capacity, leaving homing potential, viability, and differentiation intact. Furthermore, the observed down-regulation of notch1 and c-myc in Smad4−/− primitive cells places Smad4 within a network of genes involved in the regulation HSC renewal.
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| 7. |
- Mattebo, Alexander, et al.
(författare)
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Yippee like 4 (Ypel4) is essential for normal mouse red blood cell membrane integrity
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- The YPEL family genes are highly conserved across a diverse range of eukaryotic organisms and thus potentially involved in essential cellular processes. Ypel4, one of five YPEL family gene orthologs in mouse and human, is highly and specifically expressed in late terminal erythroid differentiation (TED). In this study, we investigated the role of Ypel4 in murine erythropoiesis, providing for the first time an in-depth description of a Ypel4-null phenotype in vivo. We demonstrated that the Ypel4-null mice displayed a secondary polycythemia with macro- and reticulocytosis. While lack of Ypel4 did not affect steady-state TED in the bone marrow or spleen, the anemia-recovering capacity of Ypel4-null cells was diminished. Furthermore, Ypel4-null red blood cells (RBC) were cleared from the circulation at an increased rate, demonstrating an intrinsic defect of RBCs. Scanning electron micrographs revealed an ovalocytic morphology of Ypel4-null RBCs and functional testing confirmed reduced deformability. Even though Band 3 protein levels were shown to be reduced in Ypel4-null RBC membranes, we could not find support for a physical interaction between YPEL4 and the Band 3 protein. In conclusion, our findings provide crucial insights into the role of Ypel4 in preserving normal red cell membrane integrity.
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| 8. |
- Moody, Jennifer, et al.
(författare)
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Endoglin is not critical for hematopoietic stem cell engraftment and reconstitution but regulates adult erythroid development
- 2007
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 25:11, s. 2809-2819
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Tidskriftsartikel (refereegranskat)abstract
- Endoglin is a transforming growth factor-beta (TGF-beta) accessory receptor recently identified as being highly expressed on long-term repopulating hematopoietic stem cells (HSC) However, little is known regarding its function in these cells. We have used two complementary approaches toward understanding endoglin's role in HSC biology: one that efficiently knocks down expression via lentiviral-driven short hairpin RNA and another that uses retroviral-mediated overexpression. Altering endoglin expression had functional consequences for hematopoietic progenitors in vitro such that endoglin-suppressed myeloid progenitors (colony-forming unit-granulocyte macrophage) displayed a higher degree of sensitivity to TGF-beta-mediated growth inhibition, whereas endoglin-overexpressing cells were partially resistant. However, transplantation of transduced bone marrow enriched in primitive hematopoietic stem and progenitor cells revealed that neither endoglin suppression nor endoglin overexpression affected the ability of stem cells to short-term or long-term repopulate recipient marrow. Furthermore, transplantation of cells altered in endoglin expression yielded normal white blood cell proportions and peripheral blood platelets. Interestingly, decreasing endoglin expression increased the clonogenic capacity of early blast-forming unit-erythroid progenitors, whereas overexpression compromised erythroid differentiation at the basophilic erythroblast phase, suggesting a pivotal role for endoglin at key stages of adult erythropoietic development.
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| 9. |
- Sen, Taha, et al.
(författare)
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Decreased PGC1beta expression results in disrupted human erythroid differentiation, impaired hemoglobinization and cell cycle exit
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Production of red blood cells relies on proper mitochondrial function, both for their increased energy demands during differentiation and for proper heme and iron homeostasis. Mutations in genes regulating mitochondrial function have been reported in patients with anemia, yet their pathophysiological role often remains unclear. PGC1β is a critical coactivator of mitochondrial biogenesis, with increased expression during terminal erythroid differentiation. The role of PGC1β has however mainly been studied in skeletal muscle, adipose and hepatic tissues, and its function in erythropoiesis remains largely unknown. Here we show that perturbed PGC1β expression in human hematopoietic stem/progenitor cells from both bone marrow and cord blood results in impaired formation of early erythroid progenitors and delayed terminal erythroid differentiation in vitro, with accumulations of polychromatic erythroblasts, similar to MDS-related refractory anemia. Reduced levels of PGC1β resulted in deregulated expression of iron, heme and globin related genes in polychromatic erythroblasts, and reduced hemoglobin content in the more mature bone marrow derived reticulocytes. Furthermore, PGC1β knock-down resulted in disturbed cell cycle exit with accumulation of erythroblasts in S-phase and enhanced expression of G1-S regulating genes, with smaller reticulocytes as a result. Taken together, we demonstrate that PGC1β is directly involved in production of hemoglobin and regulation of G1-S transition and is ultimately required for proper terminal erythroid differentiation.
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| 10. |
- Sen, Taha, et al.
(författare)
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Enhancing mitochondrial function in vivo rescues MDS-like anemia induced by pRb deficiency
- 2020
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Ingår i: Experimental Hematology. - : Elsevier BV. - 0301-472X. ; 88, s. 28-41
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Tidskriftsartikel (refereegranskat)abstract
- Erythropoiesis is intimately coupled to cell division, and deletion of the cell cycle regulator retinoblastoma protein (pRb) causes anemia in mice. Erythroid-specific deletion of pRb has been found to result in inefficient erythropoiesis because of deregulated coordination of cell cycle exit and mitochondrial biogenesis. However, the pathophysiology remains to be fully described, and further characterization of the link between cell cycle regulation and mitochondrial function is needed. To this end we further assessed conditional erythroid-specific deletion of pRb. This resulted in macrocytic anemia, despite elevated levels of erythropoietin (Epo), and an accumulation of erythroid progenitors in the bone marrow, a phenotype strongly resembling refractory anemia associated with myelodysplastic syndromes (MDS). Using high-fractionation fluorescence-activated cell sorting analysis for improved phenotypic characterization, we illustrate that erythroid differentiation was disrupted at the orthochromatic stage. Transcriptional profiling of sequential purified populations revealed failure to upregulate genes critical for mitochondrial function such as Pgc1β, Alas2, and Abcb7 specifically at the block, together with disturbed heme production and iron transport. Notably, deregulated ABCB7 causes ring sideroblastic anemia in MDS patients, and the mitochondrial co-activator PGC1β is heterozygously lost in del5q MDS. Importantly, the anemia could be rescued through enhanced PPAR signaling in vivo via either overexpression of Pgc1β or bezafibrate administration. In conclusion, lack of pRb results in MDS-like anemia with disrupted differentiation and impaired mitochondrial function at the orthochromatic erythroblast stage. Our findings reveal for the first time a role for pRb in heme and iron regulation, and indicate that pRb-induced anemia can be rescued in vivo through therapeutic enhancement of PPAR signaling.
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| 11. |
- Singbrant, Sofie, et al.
(författare)
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Canonical BMP signaling is dispensable for hematopoietic stem cell function in both adult and fetal liver hematopoiesis, but essential to preserve colon architecture.
- 2010
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 115, s. 4689-4698
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Tidskriftsartikel (refereegranskat)abstract
- Numerous publications have described the importance of Bone Morphogenetic Protein (BMP) signaling in the specification of hematopoietic tissue in developing embryos. Here we investigate the full role of canonical BMP signaling in both adult and fetal liver hematopoiesis using conditional knockout strategies, since conventional disruption of components of the BMP signaling pathway result in early death of the embryo. By targeting both Smad1 and Smad5, we have generated a double knockout mouse with complete disruption of canonical BMP signaling. Interestingly, concurrent deletion of Smad1 and Smad5 results in death due to extra-hematopoietic pathological changes in the colon. However, Smad1/5 deficient bone marrow (BM) cells can compete normally with wild-type cells and display unaffected self-renewal and differentiation capacity when transplanted into lethally irradiated recipients. Moreover, although BMP receptor expression is increased in fetal liver, fetal liver cells deficient in both Smad1 and Smad5 remain competent to long-term reconstitute lethally irradiated recipients in a multi-lineage manner. In conclusion, canonical BMP signaling is not required to maintain either adult or fetal liver hematopoiesis, despite its crucial role in the initial patterning of hematopoiesis in early embryonic development.
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| 12. |
- Singbrant, Sofie, et al.
(författare)
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Complex and context dependent regulation of hematopoiesis by TGF-beta superfamily signaling.
- 2009
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923. ; 1176, s. 55-69
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Forskningsöversikt (refereegranskat)abstract
- The transforming growth factor (TGF)-beta superfamily of growth factors, including the TGF-betas, activins, and bone morphogenetic proteins (BMPs), provide cells with a broad spectrum of regulatory signals through the intracellular Smad pathway. Since loss-of-function studies of a majority of the TGF-beta superfamily members result in embryonic lethality, much of our current knowledge of the TGF-beta superfamily's role in hematopoiesis is generated from studies performed in vitro, or in very early stages of embryonic development. TGF-beta is well documented as a potent inhibitor of hematopoietic stem cell (HSC) proliferation in vitro, while its role in vivo is largely unknown. BMP signaling is crucial for the initiation of hematopoiesis in the developing embryo, although its role in adult hematopoiesis remains elusive. More recently we and others have used conditional knockout models to unravel the role of several components of TGF-beta family signaling in adult hematopoiesis. Here we review the currently known functions for the major factors of this signaling family in embryonic and adult hematopoietic regulation and discuss the context dependency and complexity that permeate this regulation.
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| 13. |
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| 14. |
- Singbrant, Sofie, et al.
(författare)
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Prospective isolation of radiation induced erythroid stress progenitors reveals unique transcriptomic and epigenetic signatures enabling increased erythroid output
- 2020
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 0390-6078 .- 1592-8721. ; 105:11, s. 2561-2571
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Tidskriftsartikel (refereegranskat)abstract
- Massive expansion of erythroid progenitor cells is essential for surviving anemic stress. Research towards understanding this critical process, referred to as stress-erythropoiesis, has been hampered due to the lack of specific marker-combinations enabling analysis of the distinct stress-progenitor cells capable of providing radioprotection and enhanced red blood cell production. Here we present a method for the precise identification and in vivo validation of progenitor cells contributing to both steady-state and stress-erythropoiesis, enabling for the first time in-depth molecular characterization of these cells. Differential expression of surface markers CD150, CD9 and Sca1 defines a hierarchy of splenic stress-progenitors during irradiation-induced stress recovery in mice, and provides high-purity isolation of the functional stress erythroid burst-forming-units (stress-BFU-E) with a 100-fold improved enrichment compared to the state-of-the-art. By transplanting purified stress-progenitors expressing the fluorescent protein Kusabira Orange, we determined their kinetics in vivo and demonstrated that CD150+CD9+Sca1 -stress-BFU-E provide a massive but transient radioprotective erythroid wave, followed by multi-lineage reconstitution from CD150+CD9+Sca1+ multi-potent stem/progenitor cells. Whole genome transcriptional analysis revealed that stress-BFU-E express gene signatures more associated with erythropoiesis and proliferation compared to steady-state BFU-E, and are bone morphogenetic protein 4-responsive. Evaluation of chromatin accessibility through ATAC sequencing reveals enhanced and differential accessibility to binding sites of the chromatin-looping transcription factor CTCF in stress-BFU-E compared to steady-state BFU-E. Our findings offer a molecular insight into the unique capacity of stress-BFU-E to rapidly form erythroid cells in response to anemia and constitute an important step towards identifying novel erythropoiesis stimulating agents.
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| 15. |
- Singbrant, Sofie, et al.
(författare)
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Smad5 is dispensable for adult murine hematopoiesis.
- 2006
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 108:12, s. 3707-3712
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Tidskriftsartikel (refereegranskat)abstract
- Smad5 is known to transduce intracellular signals from bone morphogenetic proteins (BMPs), which belong to the transforming growth factor-beta (TGF-beta) superfamily and are involved in the regulation of hematopoiesis. Recent findings suggest that BMP4 stimulates proliferation of human primitive hematopoietic progenitors in vitro, while early progenitors from mice deficient in Smad5 display increased self-renewal capacity in murine embryonic hematopoiesis. Here, we evaluate the role of Smad5 in the regulation of hematopoietic stem cell (HSC) fate decisions in adult mice by using an inducible MxCre-mediated conditional knockout model. Surprisingly, analysis of induced animals revealed unperturbed cell numbers and lineage distribution in peripheral blood (PB), bone marrow (BM), and the spleen. Furthermore, phenotypic characterization of the stem cell compartment revealed normal numbers of primitive lin(-)Sca-1(+)c-Kit(+) (LSK) cells in Smad5(-/-) BM. When transplanted in a competitive fashion into lethally irradiated primary and secondary recipients, Smad5-deficient BM cells competed normally with wild-type (wt) cells, were able to provide long-term reconstitution for the hosts, and displayed normal lineage distribution. Taken together, Smad5-deficient HSCs from adult mice show unaltered differentiation, proliferation, and repopulating capacity. Therefore, in contrast to its role in embryonic hematopoiesis, Smad5 is dispensable for hematopoiesis in the adult mouse.
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| 16. |
- Singbrant, Sofie
(författare)
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THE ROLE OF BMP SIGNALING AND ENDOGLIN IN REGULATION OF HEMATOPOIESIS
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hematopoiesis, the formation of blood cells, ultimately depends on a rare population of hematopoietic stem cells (HSCs), which can both self-renew to maintain the HSC pool, and differentiate into all mature blood lineages. HSC fate decisions are governed by a complex combination of numerous signals, although the molecular mechanisms are not fully understood. This thesis describes the role of two important regulatory candidates, Bone Morphogenetic Proteins (BMP) and Endoglin in adult hematopoiesis. Several publications have described the importance of BMP signaling in specification of hematopoietic tissue in developing embryos. In Article I and II, we investigate the full role of BMP signaling in adult mice, using single and double Cre-based conditional knockout mice for the BMP signaling mediators Smad1 and Smad5. We demonstrate that BMP signaling deficient bone marrow (BM) competes normally with wild-type cells and display unperturbed self-renewal and differentiation capacity when transplanted into lethally irradiated recipients. Thus, despite its crucial role in initial patterning of hematopoiesis, BMP signaling is not required to maintain adult hematopoiesis. Endoglin is a TGF-β accessory receptor recently demonstrated to identify functional long-term HSCs, although little is known regarding its function in these cells. We have investigated the role of endoglin in hematopoiesis by both knocking down, and over-expressing its levels using viral vectors. Interestingly, our study suggests a pivotal role for endoglin in adult erythropoietic development. However, transplantation of transduced BM stem and progenitor cells reveals that neither endoglin suppression nor over-expression affects the ability of HSCs to long-term repopulate recipient marrow.
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| 17. |
- Singbrant, Sofie, et al.
(författare)
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The SKI proto-oncogene enhances the in vivo repopulation of hematopoietic stem cells and causes myeloproliferative disease
- 2014
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 99:4, s. 647-655
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Tidskriftsartikel (refereegranskat)abstract
- The proto-oncogene SKI is highly expressed in human myeloid leukemia and also in murine hematopoietic stem cells. However, its operative relevance in these cells remains elusive. We have over-expressed SKI to define its intrinsic role in hematopoiesis and myeloid neoplasms, which resulted in a robust competitive advantage upon transplantation, a complete dominance of the stem and progenitor compartments, and a marked enhancement of myeloid differentiation at the expense of other lineages. Accordingly, enforced expression of SKI induced a gene signature associated with hematopoietic stem cells and myeloid differentiation, as well as hepatocyte growth factor signaling. Here we demonstrate that, in contrast to what has generally been assumed, the significant impact of SKI on hematopoiesis is independent of its ability to inhibit TGF-beta signaling. Instead, myeloid progenitors expressing SKI are partially dependent on functional hepatocyte growth factor signaling. Collectively our results demonstrate that SKI is an important regulator of hematopoietic stem cell activity and its overexpression leads to myeloproliferative disease.
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| 18. |
- Singbrant, Sofie, et al.
(författare)
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Two new routes to make blood: Hematopoietic specification from pluripotent cell lines vs. reprogramming of somatic cells.
- 2015
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Ingår i: Experimental Hematology. - : Elsevier BV. - 1873-2399 .- 0301-472X. ; 43:9, s. 756-759
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Tidskriftsartikel (refereegranskat)abstract
- Transplantation of hematopoietic stem cells (HSCs) to treat hematological disorders is routinely used in the clinic. However, HSC therapy is hindered by the requirement of finding HLA-matched donors, as well as attaining sufficient numbers of long-term HSCs in the graft. Therefore, ex vivo expansion of transplantable HSC remains one of the "holy grails" of hematology. Without the ability to maintain and expand human HSCs in vitro, two complementary approaches involving cellular reprogramming to generate transplantable HSCs have emerged. Reprogrammed HSCs represent a potentially inexhaustible supply of autologous tissue. On March 18(th) 2015, Dr. George Q Daley and Dr. Derrick J Rossi, two pioneers in the field, presented and discussed their most recent research on these topics in a webinar organized by the International Society for Experimental Hematology (ISEH). Here we summarize these seminars, and discuss the possibilities and challenges of the field of hematopoietic specification.
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