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Signaling mechanisms coupled to tyrosines in the granulocyte colony-stimulating factor receptor orchestrate G-CSF-induced expansion of myeloid progenitor cells

journal contribution
posted on 2003-04-01, 00:00 authored by M Hermans, G J van de Geijn, C Antonissen, J Gits, D van Leeuwen, Alister WardAlister Ward, I Touw
Granulocyte colony-stimulating factor (G-CSF) is the major regulator of neutrophil production. Studies in cell lines have established that conserved tyrosines Y704, Y729, Y744, Y764 within the cytoplasmic domain of G-CSF receptor (G-CSF-R) contribute significantly to G-CSF-induced proliferation, differentiation and cell survival. However, it is unclear whether these tyrosines are equally important under more physiological conditions. Here, we investigated how individual G-CSF-R tyrosines affect G-CSF responses of primary myeloid progenitors. We generated GCSF- R deficient mice and transduced their bone marrow cells with tyrosine "null" mutant (mO), single tyrosine "add back" mutants or wild type (WT) receptors. G-CSFinduced responses were determined in primary colony assays, serial replatings and suspension cultures. We show that removal of all tyrosines had no major influence on primary colony growth. However, adding back Y764 strongly enhanced proliferativeresponses, which was reverted by inhibition of ERK activitity. Y729, which we found to be associated with the suppressor of cytokine signaling, SOCS3, had a negative effect on colony formation. After repetitive replatings, the clonogenic capacities of cells expressing mO gradually dropped compared to WT. The presence of Y729, but also Y704 and Y744, both involved in activation of STAT3, further reduced replating
efficiencies. Conversely, Y764 greatly elevated the clonogenic abilities of myeloid progenitors, resulting in a >104–fold increase of colony forming cells over mO after the fifth replating. These findings suggest that tyrosines in the cytoplasmic domain of G-CSF-R, although dispensable for G-CSF-induced colony growth, recruit signaling mechanisms that regulate the maintenance and outgrowth of myeloid progenitor cells.

History

Journal

Blood

Volume

101

Issue

7

Pagination

2584 - 2590

Publisher

American Society of Hematology

Location

Washington, D.C.

ISSN

0006-4971

eISSN

1528-0020

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2003, The American Society of Hematology.