Myeloproliferative disorder (MPD) is a heterogeneous group of hematologic diseases which share the common characteristic of myeloid cell overproduction. We have been examining the role of activating mutations of PTPN11, which encodes the protein tyrosine phosphatase, Shp-2, and of c-kit, which encodes the receptor protein tyrosine kinase for stem cell factor (SCF), in juvenile myelomonocytic leukemia and systemic mastocytosis, respectively. GM-CSF signaling via Ras hyperactivation is central to the pathogenesis of JMML; however, we have preliminary studies demonstrating correction of myeloid progenitor GM-CSF hypersensitivity induced by activating PTPN11 mutations by the lipid kinase phosphoinsositol-3-kinase (PI3K) inhibitor, LY294002; therefore, we hypothesize hyperactivation of PI3K activity also contributes to the pathogenesis of JMML. Additionally, in a model of systemic mastocytosis, we have evidence demonstrating that genetic disruption of p85a, a regulatory subunit of class IA PI3K, abrogates mast cell proliferation induced by activating c-kit mutations, leading us to hypothesize that the enhanced proliferation, survival, and migration of mast cells expressing activating c-kit mutations is mediated in part via hyperactivation of PI3K. Therefore, the central hypothesis of this application, formulated on the basis of our preliminary data, is that hyperactivation of class IA PI3K induced by activating PTPN11 and c-kit mutations contributes to the etiology of JMML and systemic mastocytosis, respectively. To examine this hypothesis, we will transduce murine hematopoietic cells lacking expression of the regulatory subunit of PI3K, p85alpha, with activating PTPN11 mutants to conduct in vitro and in vivo hematopoietic progenitor, survival, and proliferation assays as well as biochemical analysis in response to GMCSF stimulation and will utilize a genetic and a biochemical approach involving a direct comparison of the mast cells deficient in p85a or engineered to retrovirally express the activating c-Kit (D814V) mutation to look for modulation of growth, survival and activation of downstream signaling pathways in vitro and MPD in vivo. To define additional potential therapeutic targets in JMML and systemic mastocytosis, we will map the proteome and the phosphoproteome of murine mast cells and stem/progenitor cells expressing the activating mutations of c-Kit (c-Kit D814V) and PTPN11, respectively. Collectively, this combined approach of genetic, biochemical, and proteomic experiments will identify a full range of functions that are controlled by Shp-2 and c-kit via p85 subunits of class IA PI3K and will provide novel targets for molecular therapies in the treatment of JMML and systemic mastocytosis, both of which currently have no good treatment options.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL082981-01
Application #
7023407
Study Section
Special Emphasis Panel (ZHL1-CSR-I (S2))
Program Officer
Di Fronzo, Nancy L
Project Start
2005-09-15
Project End
2009-08-31
Budget Start
2005-09-15
Budget End
2006-08-31
Support Year
1
Fiscal Year
2005
Total Cost
$378,750
Indirect Cost
Name
Indiana University-Purdue University at Indianapolis
Department
Pediatrics
Type
Schools of Medicine
DUNS #
603007902
City
Indianapolis
State
IN
Country
United States
Zip Code
46202
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Goodwin, Charles B; Yang, Zhenyun; Yin, Fuqin et al. (2012) Genetic disruption of the PI3K regulatory subunits, p85?, p55?, and p50?, normalizes mutant PTPN11-induced hypersensitivity to GM-CSF. Haematologica 97:1042-7
Yang, Zhenyun; Chen, Mia; Sitarski, Sarah A et al. (2011) Genetic disruption of the scaffolding protein, Kinase Suppressor of Ras 1 (KSR1), differentially regulates GM-CSF-stimulated hyperproliferation in hematopoietic progenitors expressing activating PTPN11 mutants D61Y and E76K. Leuk Res 35:961-4
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Zhang, Xian; He, Yantao; Liu, Sijiu et al. (2010) Salicylic acid based small molecule inhibitor for the oncogenic Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2). J Med Chem 53:2482-93
Yang, Zhenyun; Kondo, Takako; Voorhorst, Cara S et al. (2009) Increased c-Jun expression and reduced GATA2 expression promote aberrant monocytic differentiation induced by activating PTPN11 mutants. Mol Cell Biol 29:4376-93
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Goodman, Michael L; Chen, Shi; Yang, Feng-Chun et al. (2009) Novel method of murine embryonic stem cell-derived osteoclast development. Stem Cells Dev 18:195-200
Yang, Zhenyun; Li, Yiping; Yin, Fuqin et al. (2008) Activating PTPN11 mutants promote hematopoietic progenitor cell-cycle progression and survival. Exp Hematol 36:1285-96

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