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| 2. |
- Jaako, Pekka, et al.
(författare)
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Dietary L-leucine improves the anemia in a mouse model for Diamond-Blackfan anemia.
- 2012
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 120:11, s. 2225-2228
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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. Recently, a case study reported a patient who became transfusion-independent in response to treatment with the amino acid L-leucine. Therefore, we have validated the therapeutic effect of L-leucine using our recently generated mouse model for RPS19-deficient DBA. Administration of L-leucine significantly improved the anemia in Rps19-deficient mice (19 % improvement in hemoglobin concentration; 18% increase in the number of erythrocytes), increased the bone marrow cellularity and alleviated stress hematopoiesis. Furthermore, the therapeutic response to L-leucine appeared specific for Rps19-deficient hematopoiesis and was associated with downregulation of p53 activity. Our study supports the rationale for clinical trials of L-leucine as a therapeutic agent for DBA.
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| 3. |
- Jaako, Pekka, et al.
(författare)
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Gene therapy cures the anemia and lethal bone marrow failure in mouse model for RPS19-deficient Diamond-Blackfan anemia.
- 2014
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 99:12, s. 1792-1798
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Tidskriftsartikel (refereegranskat)abstract
- Diamond-Blackfan anemia is a congenital erythroid hypoplasia caused by functional haploinsufficiency of genes encoding ribosomal proteins. Mutations involving the ribosomal protein S19 gene are detected in 25 % of patients. Enforced expression of ribosomal protein S19 improves the overall proliferative capacity, erythroid colony-forming potential and erythroid differentiation of hematopoietic progenitors from ribosomal protein S19-deficient patients in vitro and in vivo following xenotransplantation. However, studies using animal models are needed to assess the therapeutic efficacy and safety of the viral vectors. In the present study we have validated the therapeutic potential of gene therapy using mouse models for ribosomal protein S19-deficient Diamond-Blackfan anemia. Using lentiviral gene transfer we demonstrate that enforced expression of ribosomal protein S19 cures the anemia and lethal bone marrow failure in recipients transplanted with ribosomal protein S19-deficient cells. Furthermore, gene-corrected ribosomal protein S19-deficient cells showed an increased pan-hematopoietic contribution over time compared to untransduced cells without signs of vector-mediated toxicity. Our study provides a proof of principle for the development of clinical gene therapy to cure ribosomal protein 19-deficient Diamond-Blackfan anemia.
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| 4. |
- 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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| 5. |
- Jaako, Pekka
(författare)
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Modeling Diamond-Blackfan Anemia in the Mouse: Disease Pathogenesis and Evaluation of Novel Therapies
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia that presents early in infancy. The main hematopoietic symptoms include macrocytic anemia with reticulocytopenia and selective absence of erythroid precursors in a normocellular bone marrow. In addition to the hematopoietic symptoms, DBA is characterized by the presence of physical abnormalities and cancer predisposition. Mutations in genes encoding ribosomal proteins have been identified in approximately 60-70% of DBA patients. Among these genes, ribosomal protein S19 (RPS19) is the most common disease gene (25% of the cases). All reported patients are heterozygous for the mutations and in most cases the mutations are predicted to result in haploinsufficiency of the respective ribosomal protein. Knowledge about DBA pathophysiology has been limited due to lack of appropriate animal models. The aim of this thesis was to generate mouse models for RPS19-deficient DBA and to use these models to study DBA pathophysiology and to evaluate novel therapies. In article I we generated and characterized novel mouse models for RPS19-deficient DBA. These models contain a doxycycline-regulatable Rps19-targeting shRNA that allows an inducible and graded downregulation of Rps19. We demonstrate that Rps19-deficient mice recapitulate many of the phenotypic and molecular features seen in patients, and are therefore well suited for the evaluation of novel therapies. In article II we used these mouse models to assess the therapeutic potential of the amino acid L-leucine in the treatment of DBA. We show that L-leucine treatment improves the anemia and alleviates the stress hematopoiesis in Rps19-deficient mice. In article III we evaluated the therapeutic efficacy of gene therapy using our mouse models for RPS19-deficient DBA. Using lentiviral vectors we demonstrate that enforced expression of RPS19 cures the lethal bone marrow failure in recipient mice transplanted with Rps19-deficient bone marrow cells. Taking together the generated mouse models provide novel tools to study DBA pathophysiology and to evaluate novel therapies. Our studies strengthen the rationale for clinical trials of L-leucine and provide a proof of principle for the development of clinical gene therapy in the treatment of RPS19-deficient DBA.
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| 6. |
- 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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| 7. |
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| 8. |
- Ugale, Amol, et al.
(författare)
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Hematopoietic Stem Cells Are Intrinsically Protected against MLL-ENL-Mediated Transformation.
- 2014
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 9:4, s. 1246-1255
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Tidskriftsartikel (refereegranskat)abstract
- Studies of developmental pathways of hematopoietic stem cells (HSCs) have defined lineage relationships throughout the blood system. This is relevant to acute myeloid leukemia (AML), where aggressiveness and therapeutic responsiveness can be influenced by the initial stage of transformation. To address this, we generated a mouse model in which the mixed-lineage leukemia/eleven-nineteen-leukemia (MLL-ENL) transcription factor can be conditionally activated in any cell type. We show that AML can originate from multiple hematopoietic progenitor subsets with granulocytic and monocytic potential, and that the normal developmental position of leukemia-initiating cells influences leukemic development. However, disease failed to arise from HSCs. Although it maintained or upregulated the expression of target genes associated with leukemic development, MLL-ENL dysregulated the proliferative and repopulating capacity of HSCs. Therefore, the permissiveness for development of AML may be associated with a narrower window of differentiation than was previously appreciated, and hijacking the self-renewal capacity of HSCs by a potent oncogene is insufficient for leukemic development.
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