Primary structure and functional expression of rat and human stem cell factor DNAs

Martin, Francis H.; Suggs, Sid; Langley, Keith; Lu, Hsieng S.; Ting, Jerry; Okino, Kenneth H.; Morris, Charles F.; McNiece, Ian; Jacobsen, Frederick W.; Mendlaz, Elizabeth A.; Birkett, Neal C.; Smith, Kent; Johnson, Malcolm; Parker, Vann P.; Flores, Josephine C.; Patel, Avantika C.; Fisher, Eric; Erjavec, Holly O.; Herrera, Charles; Wypych, Jette; Sachdev, Raj; Pope, Joseph A.; Leslie, I.; Wen, Duanzhi; Lin, Chi Hwei; Cupples, Rod; Zsebo, Krisztina M.

doi:10.1016/0092-8674(90)90301-t

Cited by 695 publications

(275 citation statements)

References 37 publications

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“…22,23 Table 1 shows a comparison of the cells present in the BM, spleen and blood of untreated adult growth factor (human IL-3, GM-CSF and SF) -producing and parental (control) NOD/SCID mice. In the BM of the NOD/SCID-3/GM/SF mice, the number of myeloid (Gr-1 þ /Mac-1 þ ) cells and CFCs (primarily CFU-GMs) were modestly increased (1.5-to two-fold) and the number of erythroid (Ter119 þ ) cells was correspondingly decreased, although only the latter effect reached statistical significance (Po0.05).…”

Section: Discussionmentioning

confidence: 99%

NOD/SCID mice engineered to express human IL-3, GM-CSF and Steel factor constitutively mobilize engrafted human progenitors and compromise human stem cell regeneration

et al. 2003

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Section: Discussionmentioning

confidence: 99%

NOD/SCID mice engineered to express human IL-3, GM-CSF and Steel factor constitutively mobilize engrafted human progenitors and compromise human stem cell regeneration

et al. 2003

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“…Expression of rhSCF and Its Variants in E. coli-The construction of the expression vector for human SCF, and the fermentation conditions for expression in E. coli were reported previously (19,20). The expressed gene contains an initiating methionine codon followed by the codons for SCF 1-165.…”

Section: Methodsmentioning

confidence: 99%

The Majority of Stem Cell Factor Exists as Monomer under Physiological Conditions

Hsu

Mendiaz

et al. 1997

Journal of Biological Chemistry

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Soluble Escherichia coli-derived recombinant human stem cell factor (rhSCF) forms a non-covalently associated dimer. We have determined a dimer association constant (K a ) of 2-4 ؋ 10 8 M ؊1 , using sedimentation equilibrium and size exclusion chromatography. SCF has been shown previously to be present at concentrations of approximately 3.3 ng/ml in human serum. Based on the dimerization K a , greater than 90% of the circulating SCF would be in the monomeric form. When 125 I-rhSCF was added to human serum and the serum analyzed by size exclusion chromatography, 72-49% of rhSCF was monomer when the total SCF concentration was in the range of 10 -100 ng/ml, consistent with the K a determination. Three SCF variants, SCF(F63C), SCF (V49L,F63L), and SCF(A165C), were recombinantly expressed in Escherichia coli, purified, and characterized. The dimer K a values, biophysical properties, and biological activities of these variants were studied. Dimerization-defective variants SCF(F63C)S-CH 2 CONH 2 and SCF(V49L,F63L) showed substantially reduced mitogenic activity, while the activity of the Cys 165 -Cys 165 disulfide-linked SCF(A165C) dimer was 10-fold higher than that of wild type rhSCF. The results suggest a correlation between dimerization affinity and biological activity, consistent with a model in which SCF dimerization mediates dimerization of its receptor, Kit, and subsequent signal transduction.Stem cell factor is a cytokine that is active toward early hematopoietic cells and also plays roles in gametogenesis, melanogenesis, and mast cell function. Its biological and other properties have been extensively reviewed (1, 2). It is found in both membrane-bound and soluble forms, with the latter being derived from a membrane-bound form by proteolytic cleavage. The soluble SCF has 165 amino acids.Both soluble Escherichia coli-derived and CHO 1 cell-derived recombinant human SCF have been reported to be non-covalently associated dimers, as determined by sedimentation equilibrium and size exclusion chromatography at protein concentrations above 0.4 mg/ml (3). In a previous paper (4), we demonstrated that SCF dimer is dissociable under non-denaturing conditions and the dissociation rate constant (k d ) of E. coli-derived rhSCF dimer is approximately 1.35 ϫ 10 Ϫ4 s Ϫ1 at pH 4.8, 25°C. In the present work, we arrive at a value of 2-4 ϫ 10 8 M Ϫ1 for the dimer association constant (K a ) of E. coli-derived rhSCF, based on several approaches including ultracentrifugation and size exclusion chromatography at low SCF concentrations. Since the SCF concentration in human serum has been found previously to be a few nanograms/ml (5), the K a value suggests that the majority of SCF in serum may be monomeric. We use 125 I-SCF as a tracer added to serum to show that this does in fact appear to be the case.The binding of ligands to cell receptors, followed by receptor dimerization, is essential for signal transduction by the family of transmembrane receptor tyrosine kinases (6 -8). The receptor for SCF on target cells is Kit (see Refs....

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“…The proto-oncogene c-kit [7,8], which is a receptor for stem cell factor (SCF) [9][10][11][12][13][14], plays a critical role in early hematopoiesis. Mutations at the murine dominant-white spotting locus that maps to c-kit cause severe anemia [15].…”

Section: Introductionmentioning

confidence: 99%

Down‐modulation of c‐kit mRNA and protein expression by erythroid differentiation factor/activin A

et al. 1995

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Primary structure and functional expression of rat and human stem cell factor DNAs

Cited by 695 publications

References 37 publications

NOD/SCID mice engineered to express human IL-3, GM-CSF and Steel factor constitutively mobilize engrafted human progenitors and compromise human stem cell regeneration

NOD/SCID mice engineered to express human IL-3, GM-CSF and Steel factor constitutively mobilize engrafted human progenitors and compromise human stem cell regeneration

The Majority of Stem Cell Factor Exists as Monomer under Physiological Conditions

Down‐modulation of c‐kit mRNA and protein expression by erythroid differentiation factor/activin A

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