| 1. |
- Ali, Nicole, et al.
(författare)
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Forward RNAi screens in primary human hematopoietic stem/progenitor cells
- 2009
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 113:16, s. 3690-3695
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms regulating key fate decisions such as self-renewal and differentiation in hematopoietic stem and progenitor cells (HSPC) remain poorly understood. We report here a screening strategy developed to assess modulators of human hematopoiesis using a lentiviral short hairpin RNA (shRNA) library transduced into cord blood-derived stem/progenitor cells. To screen for modifiers of self-renewal/differentiation, we used the limited persistence of HSPCs under ex vivo culture conditions as a baseline for functional selection of shRNAs conferring enhanced maintenance or expansion of the stem/progenitor potential. This approach enables complex, pooled screens in large numbers of cells. Functional selection identified novel specific gene targets (exostoses 1) or shRNA constructs capable of altering human hematopoietic progenitor differentiation or stem cell expansion, respectively, thereby demonstrating the potential of this forward screening approach in primary human stem cell populations. (Blood. 2009; 113: 3690-3695)
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| 2. |
- Baudet, Aurelie, et al.
(författare)
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RNAi screen identifies MAPK14 as a druggable suppressor of human hematopoietic stem cell expansion.
- 2012
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 119:26, s. 6255-6258
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Tidskriftsartikel (refereegranskat)abstract
- We report on a forward RNAi screen in primary human hematopoietic stem and progenitor cells, using pooled lentiviral shRNA libraries deconvoluted by next generation sequencing. We identify MAPK14/p38α as a modulator of ex vivo stem cell proliferation and show that pharmacological inhibition of p38 dramatically enhances the stem cell activity of cultured umbilical cord blood derived hematopoietic cells. p38 inhibitors should thus be considered in strategies aiming at expanding stem cells for clinical benefit.
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| 3. |
- Björnsson, Jon Mar, et al.
(författare)
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Reduced proliferative capacity of hematopoietic stem cells deficient in hoxb3 and hoxb4
- 2003
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Ingår i: Blood. - 0006-4971 .- 1528-0020. ; 23:11, s. 3872-3883
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Tidskriftsartikel (refereegranskat)abstract
- Several homeobox transcription factors, such as HOXB3 and HOXB4, have been implicated in regulation of hematopoiesis. In support of this, studies show that overexpression of HOXB4 strongly enhances hematopoietic stem cell regeneration. Here we find that mice deficient in both Hoxb3 and Hoxb4 have defects in endogenous hematopoiesis with reduced cellularity in hematopoietic organs and diminished number of hematopoietic progenitors without perturbing lineage commitment. Analysis of embryonic day 14.5 fetal livers revealed a significant reduction in the hematopoietic stem cell pool, suggesting that the reduction in cellularity observed postnatally is due to insufficient expansion during fetal development. Primitive Lin(-) Scal(+) c-kit(+) hematopoietic progenitors lacking Hoxb3 and Hoxb4 displayed impaired proliferative capacity in vitro. Similarly, in vivo repopulating studies of Hoxb3/Hoxb4-deficient hematopoietic cells resulted in lower repopulating capability compared to normal littermates. Since no defects in homing were observed, these results suggest a slower regeneration of mutant HSC. Furthermore, treatment with cytostatic drugs demonstrated slower cell cycle kinetics of hematopoietic stem cells deficient in Hoxb3 and Hoxb4, resulting in increased tolerance to antimitotic drugs. Collectively, these data suggest a direct physiological role of Hoxb4 and Hoxb3 in regulating stem cell regeneration and that these genes are required for maximal proliferative response.
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| 4. |
- 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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| 5. |
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| 6. |
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| 7. |
- Jaako, Pekka, et al.
(författare)
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Mice with ribosomal protein S19 deficiency develop bone marrow failure and symptoms like patients with Diamond-Blackfan anemia.
- 2011
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 118, s. 6087-6096
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Tidskriftsartikel (refereegranskat)abstract
- Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia caused by a functional haploinsufficiency of genes encoding for ribosomal proteins. Among these genes, ribosomal protein S19 (RPS19) is mutated most frequently. Generation of animal models for diseases like DBA is challenging since the phenotype is highly dependent on the level of RPS19 downregulation. We report the generation of mouse models for RPS19-deficient DBA using transgenic RNA interference that allows an inducible and graded downregulation of Rps19. Rps19-deficient mice develop a macrocytic anemia together with leukocytopenia and variable platelet count that with time leads to the exhaustion of hematopoietic stem cells and bone marrow failure. Both RPS19 gene transfer and the loss of p53 rescue the DBA phenotype implying the potential of the models for testing novel therapies. This study demonstrates the feasibility of transgenic RNA interference to generate mouse models for human diseases caused by haploinsufficient expression of a gene.
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| 8. |
- Jansson, Lina, et al.
(författare)
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Joining the stem cell maintenance squad.
- 2011
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 117:19, s. 5011-5012
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Tidskriftsartikel (refereegranskat)
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| 9. |
- Jansson, Lina, et al.
(författare)
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W41/W41 blastocyst complementation: a system for genetic modeling of hematopoiesis.
- 2010
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 115:1, s. 47-50
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Tidskriftsartikel (refereegranskat)abstract
- We report a rapid and highly efficient approach to generate mice in which the hematopoietic system is derived from embryonic stem (ES) cells. We show that ES cells injected into blastocysts from the c-kit deficient W41/W41 mouse strain have a clear advantage over the W41/W41 blastocyst-derived inner cell mass cells in founding the hematopoietic system. Fetal liver HSCs from W41/W41 blastocyst complementation embryos can be transplanted to establish large cohorts of bone marrow chimeras with hematopoiesis of practically pure ES cell origin. Using ES cells with site-directed modifications we show how this system can be employed to drive inducible transgene expression in hematopoietic cells in a robust and reliable manner both in vitro and in vivo. The approach avoids the cost and time constraints associated with the creation of standard transgenic mouse strains while taking advantage of the sophisticated site-directed manipulations that are possible in ES cells.
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| 10. |
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