The long-temri objective of this research project is to define the molecular basis of polycythemia vera (PV). PV represents the ultimate phenotype of the mutant kinase, JAK2 V617F, through its effects on committed hematopoietic progenitor cells but we hypothesize that while JAK2 V617F expression is responsible for the clinical phenotype of PV, the underlying molecular mechanisms responsible for the disease reside in the hematopoietic stem cell (HSC), which does not require JAK2, and that the thrombopoietin (TPO) receptor, Mpl, is integrally Involved In these mechanisms. This hypothesis, which is based on our discovery of impaired Mpl expression in PV with an attendant increase in plasma TPO, and our observation that absence of the MPL gene abrogated the PV phenotype in a JAK2 V617F transgenic (tg) mouse model of PV, provides a mechanistic basis for understanding the pathophysiology of PV at the stem cell level and a rational approach to therapy To this end, we propose to use genetic techniques to dissect the influence of the MPL:TPO axis, and also the roles of specific genes up regulated in human PV CD34+ cells, on the behavior of HSC in the murine JAK2 V617F tg model of PV.
In Specific Aim 1, we will examine the effect of abrogation of the TPO gene on the phenotype of the JAK2 V617F tg mouse, on the size of its HSC pool and the HSC gene expression profile, by breeding with a TPO-/- mouse. Control experiments will employ mice in which Mpl function was abrogated by a point mutation or a gene knockout independent of MPL that impairs platelet production, while a neutralizing Mpl antiserum will be examined as a model of targeted therapy.
In Specific Aim 2, we will create a tg mouse expressing a PV Mpl splice variant and assess its phenotype in the presence and absence of JAK2 V617F. We also examine by crossbreeding, the effect of knocking out SPARC or LCN2, two genes that are up regulated in PV, on the phenotype of the JAK2 V617F tg mouse. Finally, in Specific Aim 3, we will use xenotranslantation in NOG mice to examine the in vivo behavior of genetically-defined PV CD34 + cells from clinically distinct PV patient populations that we have identified by gene expression profiling and unsuoervised hierarchical clustering.

Public Health Relevance

Polycythemia vera (PV) is a hematopoietic stem cell (HSC) disorder in which there is overproduction of blood cells, leading to thrombosis, marrow fibrosis, splenic enlargement and acute leukemia, at varying frequencies. We propose to define the mechanisms causing PV by focusing on the behavior of genes required by PV HSC for their survival and function, inhibition of which could provide the basis for targeted therapy in this disorder.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Program Projects (P01)
Project #
5P01CA108671-08
Application #
8722848
Study Section
Special Emphasis Panel (ZCA1-RPRB-J)
Project Start
Project End
Budget Start
2014-07-01
Budget End
2015-06-30
Support Year
8
Fiscal Year
2014
Total Cost
$360,439
Indirect Cost
$209,635
Name
Icahn School of Medicine at Mount Sinai
Department
Type
DUNS #
078861598
City
New York
State
NY
Country
United States
Zip Code
10029
Wang, Xiaoli; Haylock, David; Hu, Cing Siang et al. (2016) A thrombopoietin receptor antagonist is capable of depleting myelofibrosis hematopoietic stem and progenitor cells. Blood 127:3398-409
Divoky, Vladimir; Song, Jihyun; Horvathova, Monika et al. (2016) Delayed hemoglobin switching and perinatal neocytolysis in mice with gain-of-function erythropoietin receptor. J Mol Med (Berl) 94:597-608
Spangrude, Gerald J; Lewandowski, Daniel; Martelli, Fabrizio et al. (2016) P-Selectin Sustains Extramedullary Hematopoiesis in the Gata1 low Model of Myelofibrosis. Stem Cells 34:67-82
Migliaccio, Anna Rita (2016) To condition or not to condition-That is the question: The evolution of nonmyeloablative conditions for transplantation. Exp Hematol 44:706-12
Lu, Min; Xia, Lijuan; Liu, Yen-Chun et al. (2015) Lipocalin produced by myelofibrosis cells affects the fate of both hematopoietic and marrow microenvironmental cells. Blood 126:972-82
Wang, Xiaoli; Cho, Sool Yeon; Hu, Cing Siang et al. (2015) C-X-C motif chemokine 12 influences the development of extramedullary hematopoiesis in the spleens of myelofibrosis patients. Exp Hematol 43:100-9.e1
Kovacsovics-Bankowski, Magdalena; Kelley, Todd W; Efimova, Olga et al. (2015) Changes in peripheral blood lymphocytes in polycythemia vera and essential thrombocythemia patients treated with pegylated-interferon alpha and correlation with JAK2(V617F) allelic burden. Exp Hematol Oncol 5:28
Swierczek, S; Lima, L T; Tashi, T et al. (2015) Presence of polyclonal hematopoiesis in females with Ph-negative myeloproliferative neoplasms. Leukemia 29:2432-4
Funnell, Alister P W; Prontera, Paolo; Ottaviani, Valentina et al. (2015) 2p15-p16.1 microdeletions encompassing and proximal to BCL11A are associated with elevated HbF in addition to neurologic impairment. Blood 126:89-93
Falchi, Mario; Varricchio, Lilian; Martelli, Fabrizio et al. (2015) Dexamethasone targeted directly to macrophages induces macrophage niches that promote erythroid expansion. Haematologica 100:178-87

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