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Molecular and Cellular Biology, November 1999, p. 7436-7446, Vol. 19, No. 11
Department of
Pathology1 and Department of
Biochemistry,2 Cancer Research Laboratories,
Queen's University, Kingston, Ontario K7L 3N6, and Laboratory
of Hemopoiesis and Leukemia, Institut de Recherches Cliniques de
Montreal, Montreal, Quebec H2W 1R7,3 Canada
Received 2 August 1999/Accepted 5 August 1999
The fps/fes proto-oncogene encodes a cytoplasmic
protein-tyrosine kinase that is functionally implicated in the survival
and terminal differentiation of myeloid progenitors and in signaling from several members of the cytokine receptor superfamily. To gain
further insight into the physiological function of fps/fes, we targeted the mouse locus with a kinase-inactivating missense mutation. Mutant Fps/Fes protein was expressed at normal levels in
these mice, but it lacked detectable kinase activity. Homozygous mutant
animals were viable and fertile, and they showed no obvious defects.
Flow cytometry analysis of bone marrow showed no statistically significant differences in the levels of myeloid, erythroid, or B-cell
precursors. Subtle abnormalities observed in mutant mice included
slightly elevated total leukocyte counts and splenomegaly. In bone
marrow hematopoietic progenitor cell colony-forming assays, mutant mice
gave slightly elevated numbers and variable sizes of CFU-granulocyte
macrophage in response to interleukin-3 (IL-3) and
granulocyte-macrophage colony-stimulating factor (GM-CSF). Tyrosine
phosphorylation of Stat3 and Stat5A in bone marrow-derived macrophages
was dramatically reduced in response to GM-CSF but not to IL-3 or IL-6.
This suggests a distinct nonredundant role for Fps/Fes in signaling
from the GM-CSF receptor that does not extend to the closely related
IL-3 receptor. Lipopolysaccharide-induced Erk1/2 activation was also
reduced in mutant macrophages. These subtle molecular phenotypes
suggest a possible nonredundant role for Fps/Fes in myelopoiesis and
immune responses.
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Targeted Disruption of the Murine
fps/fes Proto-Oncogene Reveals that Fps/Fes Kinase Activity
Is Dispensable for Hematopoiesis
*
Corresponding author. Mailing address: Cancer Research
Laboratories, Departments of Pathology and Biochemistry, Department of
Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Phone: (613) 533-2813. Fax: (613) 533-6830. E-mail:
greerp{at}post.queensu.ca.
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