Design of Recombinant Stem Cell Factor–macrophage Colony Stimulating Factor Fusion Proteins and their Biological Activity In Vitro

2005 ◽  
Vol 19 (5) ◽  
pp. 319-328 ◽  
Author(s):  
Tao Chen ◽  
Jie Yang ◽  
Yuelang Wang ◽  
Chenyang Zhan ◽  
Yuhui Zang ◽  
...  
1994 ◽  
Vol 14 (12) ◽  
pp. 8432-8437
Author(s):  
B Tang ◽  
H Mano ◽  
T Yi ◽  
J N Ihle

Stem cell factor (SCF) plays a crucial role in hematopoiesis through its interaction with the receptor tyrosine kinase c-kit. However, the signaling events that are activated by this interaction and involved in the control of growth or differentiation are not completely understood. We demonstrate here that Tec, a cytoplasmic, src-related kinase, physically associates with c-kit through a region that contains a proline-rich motif, amino terminal of the SH3 domain. Following SCF binding, Tec is tyrosine phosphorylated and its in vitro kinase activity is increased. Tyrosine phosphorylation of Tec is not detected in the response to other cytokines controlling hematopoiesis, including colony-stimulating factor-1 (CSF-1), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-3 (IL-3). Conversely, the cytoplasmic kinase JAK2 is activated by IL-3 but not by SCF stimulation. The activation of distinct cytoplasmic kinases may account for the synergy seen in the actions of SCF and IL-3 on hematopoietic stem cells.


1994 ◽  
Vol 14 (12) ◽  
pp. 8432-8437 ◽  
Author(s):  
B Tang ◽  
H Mano ◽  
T Yi ◽  
J N Ihle

Stem cell factor (SCF) plays a crucial role in hematopoiesis through its interaction with the receptor tyrosine kinase c-kit. However, the signaling events that are activated by this interaction and involved in the control of growth or differentiation are not completely understood. We demonstrate here that Tec, a cytoplasmic, src-related kinase, physically associates with c-kit through a region that contains a proline-rich motif, amino terminal of the SH3 domain. Following SCF binding, Tec is tyrosine phosphorylated and its in vitro kinase activity is increased. Tyrosine phosphorylation of Tec is not detected in the response to other cytokines controlling hematopoiesis, including colony-stimulating factor-1 (CSF-1), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-3 (IL-3). Conversely, the cytoplasmic kinase JAK2 is activated by IL-3 but not by SCF stimulation. The activation of distinct cytoplasmic kinases may account for the synergy seen in the actions of SCF and IL-3 on hematopoietic stem cells.


Blood ◽  
1995 ◽  
Vol 85 (5) ◽  
pp. 1220-1228 ◽  
Author(s):  
K Sasaki ◽  
K Ikeda ◽  
K Ogami ◽  
J Takahara ◽  
S Irino

Stem cell factor (SCF) is a cytokine for hematopoietic progenitor cells and plays an important role in megakaryocyte proliferation. The UT-7 cell line was established from a patient with megakaryoblastic leukemia, and its growth and survival are strictly dependent on interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), erythropoietin (Epo), or IL-6. In this study, we showed that SCF also supported the growth of UT-7 in the absence of other cytokines and downregulated the cell surface c-kit receptors. Constitutive expression of SCF by introducing SCF expression vector made UT-7 grow factor-independently in liquid medium, but not in semisolid medium. This SCF-expressing factor-independent UT-7 (UT-7scf9) expressed the membrane bound form of SCF on their surface, but did not secrete detectable amounts of soluble SCF. UT-7scf9 formed aggregates as they grew in the absence of cytokines, and this aggregation was inhibited by adding soluble SCF into the medium. UT-7 cultured with SCF and UT-7scf9 cultured without cytokines expressed GM-CSF, and anti-GM-CSF neutralizing antibody partially inhibited their growth. These results suggest that SCF stimulated UT-7 proliferation partially through the autocrine-loop of GM-CSF, and UT-7scf9 expressed SCF mostly as a membrane-bound form, which transduces its growth signal through c-kit receptor as they aggregate by cell-to-cell interaction.


Placenta ◽  
1996 ◽  
Vol 17 (5-6) ◽  
pp. A39
Author(s):  
M. Enomoto ◽  
S. Saito ◽  
N. Harada ◽  
H. Umekage ◽  
S. Sakakura ◽  
...  

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