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Updated: Jun 22, 2026
Proliferation and Differentiation of Murine Myeloid Precursor 32D/G-CSF-R Cells
Published on: February 21, 2018
Increased c-Jun expression and reduced GATA2 expression promote aberrant monocytic differentiation induced by
Zhenyun Yang1, Takako Kondo, Cara S Voorhorst
1Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Abstract:
Juvenile myelomonocytic leukemia (JMML) is characterized by myelomonocytic cell overproduction and commonly bears activating mutations in PTPN11. Murine hematopoietic progenitors expressing activating Shp2 undergo myelomonocytic differentiation, despite being subjected to conditions that normally support only mast cells. Evaluation of hematopoietic-specific transcription factor expression indicates reduced GATA2 and elevated c-Jun in mutant Shp2-expressing progenitors. We hypothesized that mutant Shp2-induced Ras hyperactivation promotes c-Jun phosphorylation and constitutive c-Jun expression, permitting, as a coactivator of PU.1, excessive monocytic differentiation and reduced GATA2. Hematopoietic progenitors expressing activating Shp2 demonstrate enhanced macrophage CFU (CFU-M) compared to that of wild-type Shp2-expressing cells. Treatment with the JNK inhibitor SP600125 or cotransduction with GATA2 normalizes activating Shp2-generated CFU-M. However, cotransduction of DeltaGATA2 (lacking the C-terminal zinc finger, needed to bind PU.1) fails to normalize CFU-M. NIH 3T3 cells expressing Shp2E76K produce higher levels of luciferase expression directed by the macrophage colony-stimulating factor receptor (MCSFR) promoter, which utilizes c-Jun as a coactivator of PU.1. Coimmunoprecipitation demonstrates increased c-Jun-PU.1 complexes in mutant Shp2-expressing hematopoietic progenitors, while chromatin immunoprecipitation demonstrates increased c-Jun binding to the c-Jun promoter and an increased c-Jun-PU.1 complex at the Mcsfr promoter. Furthermore, JMML progenitors express higher levels of c-JUN than healthy controls, substantiating the disease relevance of these mechanistic findings.
Insights
Activating mutations in PTPN11 drive juvenile myelomonocytic leukemia (JMML) by promoting excessive monocytic differentiation via c-Jun. Restoring GATA2 levels or inhibiting JNK normalizes this aberrant cell production in JMML progenitors.
Area of Science:
- Hematology
- Molecular Biology
- Cancer Research
Background:
- Juvenile myelomonocytic leukemia (JMML) is a rare pediatric cancer characterized by excessive production of myelomonocytic cells.
- Activating mutations in the PTPN11 gene, encoding the SHP2 protein, are frequently observed in JMML patients.
- SHP2 is a protein tyrosine phosphatase involved in various cellular signaling pathways, including RAS-MAPK signaling.
Purpose of the Study:
- To investigate the molecular mechanisms by which mutant SHP2 contributes to myelomonocytic differentiation in JMML.
- To explore the role of transcription factors GATA2 and c-Jun in SHP2-driven myelomonocytic leukemia.
- To identify potential therapeutic targets for JMML based on these mechanistic insights.
Main Methods:
- Utilized murine hematopoietic progenitors expressing activating SHP2 mutations.
- Assessed hematopoietic-specific transcription factor expression (GATA2, c-Jun).
- Employed JNK inhibitor (SP600125) and gene cotransduction (GATA2, DeltaGATA2) to modulate cellular differentiation.
- Performed luciferase reporter assays to evaluate promoter activity (MCSFR).
- Utilized coimmunoprecipitation and chromatin immunoprecipitation to analyze protein-DNA interactions.
Main Results:
- Activating SHP2 mutations induced myelomonocytic differentiation and enhanced macrophage colony-forming unit (CFU-M) formation.
- Mutant SHP2 led to reduced GATA2 and elevated c-Jun expression in hematopoietic progenitors.
- JNK inhibition or GATA2 restoration normalized SHP2-induced CFU-M, while DeltaGATA2 failed to do so.
- Increased c-Jun-PU.1 complex formation was observed at the MCSFR promoter, correlating with higher luciferase expression.
- JMML progenitors exhibited higher c-JUN expression compared to healthy controls.
Conclusions:
- Mutant SHP2-induced RAS hyperactivation promotes c-Jun phosphorylation and constitutive expression, leading to excessive monocytic differentiation in JMML.
- GATA2 acts as a critical suppressor of monocytic differentiation, and its reduction by mutant SHP2 contributes to JMML pathogenesis.
- Targeting the c-Jun/PU.1 pathway or restoring GATA2 function may represent viable therapeutic strategies for JMML.
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