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Distinct roles for long-term hematopoietic stem cells and erythroid precursor cells in a murine model of Jak2V617F-mediated polycythemia vera.

ABSTRACT: In the current model of the pathogenesis of polycythemia vera (PV), the JAK2V617F mutation arises in hematopoietic stem cells (HSCs) that maintain the disease, while erythroid precursor populations expand, resulting in excessive red blood cell production. We examined the role of these specific cell populations using a conditional Jak2V617F knockin murine model. We demonstrate that the most immature long-term (LT) HSCs are solely responsible for initiating and maintaining the disease in vivo and that Jak2V617F mutant LT-HSCs dominate hematopoiesis over time. When we induced Jak2V617F expression in erythropoietin receptor expressing precursor cells, the mice developed elevated hematocrit, expanded erythroid precursors, and suppressed erythropoietin levels. However, the disease phenotype was significantly attenuated compared with mice expressing Jak2V617F in LT-HSCs. In addition to developing a PV phenotype, all mice transplanted with Jak2V617F LT-HSCs underwent myelofibrotic transformation over time. These findings recapitulate the development of post-PV myelofibrosis in human myeloproliferative neoplasms. In aggregate, these results demonstrate the distinct roles of LT-HSCs and erythroid precursors in the pathogenesis of PV.

SUBMITTER: Mullally A

PROVIDER: S-EPMC3390954 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Depletion of Jak2V617F MPN-propagating stem cells by interferon-alpha in a murine model of polycythemia vera

Project description:Interferon alpha (IFNa) is an effective treatment for patients with myeloproliferative neoplasms (MPN). In addition to inducing hematological responses in most MPN patients, IFNa reduces the JAK2V617F allelic burden and can render the JAK2V617F mutant clone undetectable in some patients. The precise mechanism underlying these responses is incompletely understood and whether the molecular responses that are seen occur due to the effects of IFNa on JAK2V617F mutant stem cells is debated. Using a murine model of Jak2V617F MPN, we investigated the effects of IFNa on Jak2V617F MPN-propagating stem cells in vivo. We report that IFNa treatment induces hematological responses in the model and causes depletion of Jak2V617F MPN-propagating cells over time, impairing disease transplantation. We demonstrate that IFNa treatment induces cell-cycle activation of Jak2V617F mutant long-term hematopoietic stem cells (LT-HSC) and promotes a predetermined erythroid-lineage differentiation program. These findings provide insights into the differential effects of IFNa on Jak2V617F mutant and normal hematopoiesis and suggest that IFNa achieves molecular remissions in MPN patients through its effects on MPN stem cells. Furthermore, these results support combinatorial therapeutic approaches in MPN, by concurrently depleting dormant JAK2V617F MPN-propagating stem cells with IFNa and targeting the proliferating downstream progeny with JAK2-inhibitors or cytotoxic chemotherapy.

2013-03-09 | GSE44961 | GEO

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