Regulation of myeloproliferation and M2 macrophage programming in mice by Lyn/Hck, SHIP, and Stat5
Wenbin Xiao, … , Clifford A. Lowell, Toshiaki Kawakami
Wenbin Xiao, … , Clifford A. Lowell, Toshiaki Kawakami
Published February 1, 2008
Citation Information: J Clin Invest. 2008;118(3):924-934. https://doi.org/10.1172/JCI34013.
View: Text | PDF
Research Article Hematology

Regulation of myeloproliferation and M2 macrophage programming in mice by Lyn/Hck, SHIP, and Stat5

Abstract

The proliferation and differentiation of hematopoietic stem cells (HSCs) is finely regulated by extrinsic and intrinsic factors via various signaling pathways. Here we have shown that, similar to mice deficient in the lipid phosphatase SHIP, loss of 2 Src family kinases, Lyn and Hck, profoundly affects HSC differentiation, producing hematopoietic progenitors with increased proliferation, reduced apoptosis, growth factor–independent survival, and skewed differentiation toward M2 macrophages. This phenotype culminates in a Stat5-dependent myeloproliferative disease that is accompanied by M2 macrophage infiltration of the lung. Expression of a membrane-bound form of SHIP in HSCs lacking both Lyn and Hck restored normal hematopoiesis and prevented myeloproliferation. In vitro and in vivo studies suggested the involvement of autocrine and/or paracrine production of IL-3 and GM-CSF in the increased proliferation and myeloid differentiation of HSCs. Thus, this study has defined a myeloproliferative transformation-sensitive signaling pathway, composed of Lyn/Hck, SHIP, autocrine/paracrine cytokines, and Stat5, that regulates HSC differentiation and M2 macrophage programming.

Authors

Wenbin Xiao, Hong Hong, Yuko Kawakami, Clifford A. Lowell, Toshiaki Kawakami

×

Figure 7

Cytokines secreted from dko and SHIP–/– cells promote in vitro and in vivo expansion of myeloid cells in a autocrine/paracrine manner.

Options: View larger image (or click on image) Download as PowerPoint
Cytokines secreted from dko and SHIP–/– cells promote in vitro and in vi...
(A and B) In vivo paracrine effect of dko and SHIP–/– cells. Equal numbers of CD45.1+ (Ly5.1) BM cells and CD45.2+ (Ly5.2) BM cells derived from either WT, dko, or SHIP–/– mice were cotransferred into lethally irradiated Ly5.1 recipients. Eight weeks later, CD45.1 or CD45.2 cells in peripheral blood were gated and Gr-1+CD11b+ myeloid cells were enumerated. Percentages of Gr-1+CD11b+ cells within each CD45 cohort are indicated. (C) RNAs from WT, dko, or SHIP–/– KSL cells transduced with the indicated bicistronic vectors were submitted to real-time PCR analysis. *P < 0.05 versus WT/vector, #P < 0.05 versus dko/vector values, by Student’s t test. (D) Intracellular staining of IL-3 and GM-CSF in WT and dko KSL cells. (E) Lin– cells (Ly5.1) were cocultured for a week with either WT, dko, or SHIP–/– Lin– cells (Ly5.2+) in the presence of control IgG, anti–IL-3, anti–GM-CSF, or anti–IL-3 plus anti–GM-CSF. CD11b+ cells were enumerated by flow cytometry. (F) A proposed model. Both Lyn and Hck are required to fully activate SHIP that in turn inhibits the production of several cytokines. In the absence of Lyn and Hck, secreted cytokines, including IL-3 and GM-CSF, can activate the Jak2/Stat5 pathway, eventually disrupting the homeostasis of HSCs.