STAT1 promotes megakaryopoiesis downstream of GATA-1 in mice
Zan Huang, … , Mitchell J. Weiss, John D. Crispino
Zan Huang, … , Mitchell J. Weiss, John D. Crispino
Published December 3, 2007
Citation Information: J Clin Invest. 2007;117(12):3890-3899. https://doi.org/10.1172/JCI33010.
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Research Article Hematology

STAT1 promotes megakaryopoiesis downstream of GATA-1 in mice

Abstract

Thrombocytosis is associated with inflammation, and certain inflammatory cytokines, including IFN-γ, stimulate megakaryocyte and platelet production. However, the roles of IFN-γ and its downstream effector STAT1 in megakaryocyte development are poorly understood. We previously reported that STAT1 expression was significantly downregulated in Gata1-knockdown murine megakaryocytes, which also have impaired terminal maturation. Here, we show that ectopic expression of STAT1, or its target effector IRF-1, rescued multiple defects in Gata1-deficient megakaryopoiesis in mice, inducing polyploidization and expression of a subset of platelet-expressing genes. Enforced expression of STAT1, IRF-1, or GATA-1 enhanced phosphorylation of STAT1, STAT3, and STAT5 in cultured Gata1-deficient murine megakaryocytes, with concomitant megakaryocyte maturation. In contrast, enhanced thrombopoietin signaling, conferred by enforced expression of constitutively active JAK2 or c-MPL, induced phosphorylation of STAT3 and STAT5, but not STAT1, and failed to rescue megakaryocyte maturation. Finally, megakaryocytes from Stat1–/– mice were defective in polyploidization. Together, these findings reveal a unique role for STAT1 in megakaryopoiesis and provide new insights into how GATA-1 regulates this process. Our studies elucidate potential mechanisms by which various inflammatory disorders can cause elevated platelet counts.

Authors

Zan Huang, Terri D. Richmond, Andrew G. Muntean, Dwayne L. Barber, Mitchell J. Weiss, John D. Crispino

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Figure 1

STAT1 signaling promotes megakaryocytic differentiation in G1ME cells.

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STAT1 signaling promotes megakaryocytic differentiation in G1ME cells. (...
(A) G1ME cells were transduced with retroviral constructs expressing GFP alone or bicistronically expressing GFP plus GATA-1, GFP plus STAT1, or GFP plus IRF-1. Two days after infection, transduced cells were collected and megakaryocytic differentiation was assayed by flow cytometry. A gate was set on GFP+ cells. The cell size was measured with forward side scatter. (B) The polyploidy of transduced cells was analyzed by staining with propidium iodide (PI). (C) Cell-surface expression of CD42 was determined by staining with PE-labeled anti-CD42 antibody. (D) The expression of lineage-specific genes in the transduced G1ME cells was detected by quantitative RT-PCR. (E) G1ME cells were also treated with or without 20 ng/ml of IFN-γ for 3 days. The polyploidy of treated cells was measured by staining with PI and analyzed by flow cytometry. Data are representative of 3 independent experiments with similar results.