Dataset Information

Flt3 signaling regulates the proliferation, survival, and maintenance of multipotent hematopoietic progenitors that generate B cell precursors.

ABSTRACT: Flt3 signaling plays a crucial role in regulating the survival and differentiation of lymphoid progenitors into B cell precursors (BCPs) in bone marrow. To define further the role of Flt3 signaling in lymphoid progenitor survival, mice deficient in Flt3 ligand that also expressed a Bcl2 transgene (E?-bcl2tg flt3l(-/-)) were generated. Intracellular flow cytometry established transgene expression in primitive hematopoietic progenitors, including lineage-negative Sca-1(+) c-kit(+) (LSK(+)) CD27(-) cells enriched for functional hematopoietic stem cells. Compared with flt3l(-/-) mice, E?-bcl2tg flt3l(-/-) mice had significantly increased multipotential progenitors (MPPs), IL-7R(+) common lymphoid progenitors, and B cell precursors. To determine whether forced expression of Bcl2 was sufficient to restore lymphoid priming in the absence of Flt3 signaling E?-bcl2tg flt3l(-/-)rag1-gfp(+) mice were generated. Analysis of E?-bcl2tg flt3l(-/-)rag1-gfp(+) mice revealed that the Bcl2 transgene had no effect on lymphoid priming before CD19 expression. Thus, forced expression of a survival gene can bypass the requirement for threshold levels of Flt3 signaling requisite for lymphoid priming. Temporal Flt3 ligand (FL) replacement therapy in flt3l(-/-) mice revealed specific requirements for Flt3 signaling in the expansion and maintenance of Flt3(+hi) MPP and Flt3(+) all lymphoid progenitors, but not Flt3(+) B lymphoid progenitors (BLPs), the immediate precursors of BCPs. BCPs were restored after temporal in vivo FL treatment, albeit with delayed kinetics. Together, these results show that Flt3 regulates the proliferation, survival, and maintenance of developmental stage-specific hematopoietic progenitors that give rise to BCPs.

SUBMITTER: Dolence JJ

PROVIDER: S-EPMC4089881 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Flt3 signaling regulates the proliferation, survival, and maintenance of multipotent hematopoietic progenitors that generate B cell precursors.

Dolence Joseph J JJ Gwin Kimberly A KA Shapiro Mariya B MB Medina Kay L KL

Experimental hematology 20140118 5

Flt3 signaling plays a crucial role in regulating the survival and differentiation of lymphoid progenitors into B cell precursors (BCPs) in bone marrow. To define further the role of Flt3 signaling in lymphoid progenitor survival, mice deficient in Flt3 ligand that also expressed a Bcl2 transgene (Eμ-bcl2tg flt3l(-/-)) were generated. Intracellular flow cytometry established transgene expression in primitive hematopoietic progenitors, including lineage-negative Sca-1(+) c-kit(+) (LSK(+)) CD27(-) ...[more]

PMID: 24444745

Similar Datasets

Project description:Interleukin-7 (IL-7) and Flt3-ligand (FL) are two cytokines important for the generation of B cells, as manifested by the impaired B cell development in mice deficient for either cytokine or their respective receptors and by the complete block in B cell differentiation in the absence of both cytokines. IL-7 is an important survival and proliferation factor for B cell progenitors, whereas FL acts on several early developmental stages, prior to B cell commitment. We have generated mice constitutively over-expressing both IL-7 and FL. These double transgenic mice develop splenomegaly and lymphadenopathy characterized by tremendously enlarged lymph nodes even in young animals. Lymphoid, myeloid and dendritic cell numbers are increased compared to mice over-expressing either of the two cytokines alone and the effect on their expansion is synergistic, rather than additive. B cell progenitors, early progenitors with myeloid and lymphoid potential (EPLM), common lymphoid progenitors (CLP) and lineage-, Sca1+, kit+ (LSK) cells are all increased not only in the bone marrow but also in peripheral blood, spleen and even lymph nodes. When transplanted into irradiated wild-type mice, lymph node cells show long-term multilineage reconstitution, further confirming the presence of functional hematopoietic progenitors therein. Our double transgenic mouse model shows that sustained and combined over-expression of IL-7 and FL leads to a massive expansion of most bone marrow hematopoietic progenitors and to their associated presence in peripheral lymphoid organs where they reside and potentially differentiate further, thus leading to the synergistic increase in mature lymphoid and myeloid cell numbers. The present study provides further in vivo evidence for the concerted action of IL-7 and FL on lymphopoiesis and suggests that extramedullary niches, including those in lymph nodes, can support the survival and maintenance of hematopoietic progenitors that under physiological conditions develop exclusively in the bone marrow.

Project description:p53 is a central mediator of cellular stress responses, and its precise regulation is essential for the normal progression of hematopoiesis. MYSM1 is an epigenetic regulator essential for the maintenance of hematopoietic stem cell (HSC) function, hematopoietic progenitor survival, and lymphocyte development. We recently demonstrated that all developmental and hematopoietic phenotypes of Mysm1 deficiency are p53-mediated and rescued in the Mysm1(-/-)p53(-/-) mouse model. However, the mechanisms triggering p53 activation in Mysm1(-/-) HSPCs, and the pathways downstream of p53 driving different aspects of the Mysm1(-/-) phenotype remain unknown. Here we show the transcriptional activation of p53 stress responses in Mysm1(-/-) HSPCs. Mechanistically, we find that the MYSM1 protein associates with p53 and colocalizes to promoters of classical p53-target genes Bbc3/PUMA (p53 upregulated modulator of apoptosis) and Cdkn1a/p21. Furthermore, it antagonizes their p53-driven expression by modulating local histone modifications (H3K27ac and H3K4me3) and p53 recruitment. Using double-knockout mouse models, we establish that PUMA, but not p21, is an important mediator of p53-driven Mysm1(-/-) hematopoietic dysfunction. Specifically, Mysm1(-/-)Puma(-/-) mice show full rescue of multipotent progenitor (MPP) viability, partial rescue of HSC quiescence and function, but persistent lymphopenia. Through transcriptome analysis of Mysm1(-/-)Puma(-/-) MPPs, we demonstrate strong upregulation of other p53-induced mediators of apoptosis and cell-cycle arrest. The full viability of Mysm1(-/-)Puma(-/-) MPPs, despite strong upregulation of many other pro-apoptotic mediators, establishes PUMA as the essential non-redundant effector of p53-induced MPP apoptosis. Furthermore, we identify potential mediators of p53-dependent but PUMA-independent Mysm1(-/-)hematopoietic deficiency phenotypes. Overall, our study provides novel insight into the cell-type-specific roles of p53 and its downstream effectors in hematopoiesis using unique models of p53 hyperactivity induced by endogenous stress. We conclude that MYSM1 is a critical negative regulator of p53 transcriptional programs in hematopoiesis, and that its repression of Bbc3/PUMA expression is essential for MPP survival, and partly contributes to maintaining HSC function.

Dataset Information

Flt3 signaling regulates the proliferation, survival, and maintenance of multipotent hematopoietic progenitors that generate B cell precursors.

Publications

Flt3 signaling regulates the proliferation, survival, and maintenance of multipotent hematopoietic progenitors that generate B cell precursors.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets