| 1. |
- Bestas, Burcu, et al.
(författare)
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Splice-correcting oligonucleotides restore BTK function in X-linked agammaglobulinemia model
- 2014
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Ingår i: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 124:9, s. 4067-4081
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Tidskriftsartikel (refereegranskat)abstract
- X-linked agammaglobulinemia (XLA) is an inherited immunodeficiency that results from mutations within the gene encoding Bruton's tyrosine kinase (BTK). Many XLA-associated mutations affect splicing of BTK pre-mRNA and severely impair B cell development. Here, we assessed the potential of antisense, splice-correcting oligonucleotides (SCOs) targeting mutated BTKtranscripts for treating XLA. Both the SCO structural design and chemical properties were optimized using 2'-O-methyl, locked nucleic acid, or phosphorodiamidate morpholino backbones. In order to have access to an animal model of XLA, we engineered a transgenic mouse that harbors a BAC with an authentic, mutated, splice-defective human BTK gene. BTK transgenic mice were bred onto a Btk knockout background to avoid interference of the orthologous mouse protein. Using this model, we determined that BTK-specific SCOs are able to correct aberrantly spliced BTK in B lymphocytes, including pro-B cells. Correction of BTK mRNA restored expression of functional protein, as shown both by enhanced lymphocyte survival and reestablished BTK activation upon B cell receptor stimulation. Furthermore, SCO treatment corrected splicing and restored BTK expression in primary cells from patients with XLA. Together, our data demonstrate that SCOs can restore BTK function and that BTK-targeting SCOs have potential as personalized medicine in patients with XLA.
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| 2. |
- Bouderlique, Thibault, et al.
(författare)
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The Concerted Action of E2-2 and HEB Is Critical for Early Lymphoid Specification
- 2019
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The apparition of adaptive immunity in Gnathostomata correlates with the expansion of the E-protein family to encompass E2-2, HEB, and E2A. Within the family, E2-2 and HEB are more closely evolutionarily related but their concerted action in hematopoiesis remains to be explored. Here we show that the combined disruption of E2-2 and HEB results in failure to express the early lymphoid program in Common lymphoid precursors (CLPs) and a near complete block in B-cell development. In the thymus, Early T-cell progenitors (ETPs) were reduced and T-cell development perturbed, resulting in reduced CD4 T- and increased γδ T-cell numbers. In contrast, hematopoietic stem cells (HSCs), erythro-myeloid progenitors, and innate immune cells were unaffected showing that E2-2 and HEB are dispensable for the ancestral hematopoietic lineages. Taken together, this E-protein dependence suggests that the appearance of the full Gnathostomata E-protein repertoire was critical to reinforce the gene regulatory circuits that drove the emergence and expansion of the lineages constituting humoral immunity.
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| 3. |
- Broeske, Ann-Marie, et al.
(författare)
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DNA methylation protects hematopoietic stem cell multipotency from myeloerythroid restriction
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:11, s. 69-1207
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Tidskriftsartikel (refereegranskat)abstract
- DNA methylation is a dynamic epigenetic mark that undergoes extensive changes during differentiation of self-renewing stem cells. However, whether these changes are the cause or consequence of stem cell fate remains unknown. Here, we show that alternative functional programs of hematopoietic stem cells (HSCs) are governed by gradual differences in methylation levels. Constitutive methylation is essential for HSC self-renewal but dispensable for homing, cell cycle control and suppression of apoptosis. Notably, HSCs from mice with reduced DNA methyltransferase 1 activity cannot suppress key myeloerythroid regulators and thus can differentiate into myeloerythroid, but not lymphoid, progeny. A similar methylation dosage effect controls stem cell function in leukemia. These data identify DNA methylation as an essential epigenetic mechanism to protect stem cells from premature activation of predominant differentiation programs and suggest that methylation dynamics determine stem cell functions in tissue homeostasis and cancer.
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| 4. |
- Böiers, Charlotta, et al.
(författare)
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Expression and role of FLT3 in regulation of the earliest stage of normal granulocyte-monocyte progenitor development.
- 2010
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; May 4, s. 5061-5068
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Tidskriftsartikel (refereegranskat)abstract
- Mice deficient in FLT3 signalling have reductions in early multipotent and lymphoid progenitors, whereas no evident myeloid phenotype has been reported. However, activating mutations of Flt3 are among the most common genetic events in acute myeloid leukemia and mice harbouring internal tandem duplications within Flt3 (Flt3-ITD) develop myeloproliferative disease, with characteristic expansion of granulocyte-monocyte (GM) progenitors, possibly compatible with FLT3-ITD promoting a myeloid fate of multipotent progenitors. Alternatively, FLT3 might be expressed at the earliest stages of GM development. Herein, we investigated the expression, function and role of FLT3 in recently identified early GM progenitors. Flt3-cre fate mapping established that most progenitors and mature progeny of the GM lineage are derived from Flt3 expressing progenitors. A higher expression of FLT3 was found in preGMP compared to GMP, and preGMPs were more responsive to stimulation with FLT3 ligand (FL). Whereas preGMPs and GMPs were reduced in Fl(-/-) mice, megakaryocyte-erythroid progenitors were unaffected and lacked FLT3 expression. Notably, mice deficient in both Thrombopoietin (THPO) and FL, had a more pronounced GM progenitor phenotype than Thpo(-/-) mice, establishing a role of FL in THPO-dependent and independent regulation of GM progenitors, of likely significance for myeloid malignancies with Flt3-ITD mutations.
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| 5. |
- Böiers, Charlotta, et al.
(författare)
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Lymphomyeloid Contribution of an Immune-Restricted Progenitor Emerging Prior to Definitive Hematopoietic Stem Cells.
- 2013
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Ingår i: Cell Stem Cell. - : Elsevier BV. - 1934-5909 .- 1875-9777. ; 13:5, s. 535-548
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Tidskriftsartikel (refereegranskat)abstract
- In jawed vertebrates, development of an adaptive immune-system is essential for protection of the born organism against otherwise life-threatening pathogens. Myeloid cells of the innate immune system are formed early in development, whereas lymphopoiesis has been suggested to initiate much later, following emergence of definitive hematopoietic stem cells (HSCs). Herein, we demonstrate that the embryonic lymphoid commitment process initiates earlier than previously appreciated, prior to emergence of definitive HSCs, through establishment of a previously unrecognized entirely immune-restricted and lymphoid-primed progenitor. Notably, this immune-restricted progenitor appears to first emerge in the yolk sac and contributes physiologically to the establishment of lymphoid and some myeloid components of the immune-system, establishing the lymphomyeloid lineage restriction process as an early and physiologically important lineage-commitment step in mammalian hematopoiesis.
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| 6. |
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| 7. |
- Jensen, Christina, et al.
(författare)
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FLT3 ligand and not TSLP is the key regulator of IL-7-independent B-1 and B-2 B Lymphopoiesis.
- 2008
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 112, s. 2297-2304
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Tidskriftsartikel (refereegranskat)abstract
- Phenotypically and functionally distinct progenitors and developmental pathways have been proposed to exist for fetally-derived B-1 and conventional B-2 cells. Although IL-7 appears to be the primary regulator of fetal and adult B lymphopoiesis in mice, considerable fetal B lymphopoiesis and postnatal B-cells are sustained in the absence of IL-7, and in man B-cell generation is suggested to be largely or entirely IL-7-independent, as severe combined immune-deficient patients with IL-7-deficiency appear to have normal B-cell numbers. However, the role of other cytokines in IL-7-independent B lymphopoiesis remains to be established. Although thymic stromal lymphopoietin (TSLP) has been proposed to be the main factor driving IL-7-independent B lymphopoiesis, and to distinguish fetal from adult B-cell progenitor development in mice, recent studies failed to support a primary role of TSLP in IL-7-independent fetal B-cell development. However, the role of TSLP in IL-7-independent adult B lymphopoiesis and in particular in regulation of B-1 cells remains to be established. Herein, we demonstrate that rather than TSLP, IL-7 and FLT3 ligand (FLT3L) are combined responsible for all B-cell generation in mice, including recently identified B-1-specified cell progenitors. Thus, the same IL-7 and FLT3L-mediated signaling regulate alternative cellular pathways of fetal and adult B-1 and B-2 B lymphopoiesis.
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| 8. |
- Jensen, Christina, et al.
(författare)
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Permissive roles of hematopoietin and cytokine tyrosine kinase receptors in early T-cell development
- 2008
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 111:4, s. 2083-2090
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Tidskriftsartikel (refereegranskat)abstract
- Although several cytokines have been demonstrated to be critical regulators of development of multiple blood cell lineages, it remains disputed to what degree they act through instructive or permissive mechanisms. Signaling through the FMS-like tyrosine kinase 3 (FLT3) receptor and the hematopoietin IL-7 receptor alpha (IL-7Ralpha) has been demonstrated to be of critical importance for sustained thymopoiesis. Signaling triggered by IL-7 and thymic stromal lymphopoietin (TSLP) is dependent on IL-7Ralpha, and both ligands have been implicated in T-cell development. However, we demonstrate that, whereas thymopoiesis is abolished in adult mice doubly deficient in IL-7 and FLT3 ligand (FLT3L), TSLP does not play a key role in IL-7-independent or FLT3L-independent T lymphopoiesis. Furthermore, whereas previous studies implicated that the role of other cytokine tyrosine kinase receptors in T lymphopoiesis might not involve permissive actions, we demonstrate that ectopic expression of BCL2 is sufficient not only to partially correct the T-cell phenotype of Flt3l(-/-) mice but also to rescue the virtually complete loss of all discernable stages of early T lymphopoiesis in Flt3l(-/-)Il7r(-/-) mice. These findings implicate a permissive role of cytokine receptors of the hematopoietin and tyrosine kinase families in early T lymphopoiesis.
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| 9. |
- Jensen, Christina, et al.
(författare)
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TSLP-mediated fetal B lymphopoiesis?
- 2007
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Ingår i: Nature Immunology. - : Springer Science and Business Media LLC. - 1529-2908 .- 1529-2916. ; 8:9, s. 897-897
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Kharazi, Shabnam
(författare)
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FLT3 receptor in normal and malignant hematopoiesis
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- All hematopoietic cells originate from hematopoietic stem cells (HSCs) residing in the bone marrow (BM). The classical model of hematopoietic lineage commitment, that has been the prevailing model for hematopoiesis, proposes that the first lineage commitment step of HSCs and progenitors results in a strict separation of myelopoiesis and lymphopoiesis. However, an alternative model has already been suggested by introducing the lymphoid-primed multipotent progenitors (LMPPs) which highly express the receptor tyrosine kinase FLT3, and have sustained lymphoid and myeloid potentials, but little or no megakaryocyte/erythroid (MkE) potential. In this work, we further characterized LMPPs by applying clonal single cell culture assay, global gene expression analysis and multiplex single cell PCR assay. We demonstrated that LMPPs could generate myeloid, B- and T- cells at very high frequencies in culture but had very low MkE potential, and that MkE transcriptional priming was downregulated in LMPPs whereas lymphoid priming was upregulated, and lymphoid genes were coexpressed with myeloid genes. We could also show that the MkE potential of LMPP segregated almost entirely with the expression of thrombopoietin receptor (THPOR) in this population. Besides, using RAG1-GFP reporter mice, we could demonstrate that the GM potential is sustained but gradually reduced with increasing levels of lymphoid transcriptional priming within the LMPP compartment, suggesting the lineage restriction process from HSCs to LMPPs occurs as a gradual process. FLT3 plays an important role in normal hematopoiesis. Moreover, gain of function mutations of FLT3 has been reported in about one third of acute myeloid leukemia (AML) patients. The most common mutation of FLT3 is the internal tandem duplication (ITD) of its juxtamembrane domain, which confers a poor clinical prognosis. The clinical outcome is even worse in those patients who lose the FLT3 wild type (WT) gene. Using an Flt3-ITD knockin mouse model crossed with FLT3 receptor knockout mice, we could demonstrate that the development of a myeloproliferative disease in these mice is dependent both on ITD gene dosage as well as the absence of the WT allele. Further, we found that the development of the myeloproliferative disease in Flt3-ITD homozygous mice was FLT3 ligand independent.
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