scholarly journals An Allelic Series of Mutations in the Kit ligand Gene of Mice. I. Identification of Point Mutations in Seven Ethylnitrosourea-Induced KitlSteel Alleles

Genetics ◽  
2002 ◽  
Vol 162 (1) ◽  
pp. 331-340 ◽  
Author(s):  
S Rajaraman ◽  
W S Davis ◽  
A Mahakali-Zama ◽  
H K Evans ◽  
L B Russell ◽  
...  
Keyword(s):  
Receptor Tyrosine Kinase ◽  
Stem Cell Factor ◽  
Genetic Resource ◽  
Point Mutations ◽  
Exon Skipping ◽  
Missense Mutations ◽  
Allelic Series ◽  
Kit Ligand ◽  
Kit Receptor ◽  
Induced Mutants

Abstract An allelic series of mutations is an extremely valuable genetic resource for understanding gene function. Here we describe eight mutant alleles at the Steel (Sl) locus of mice that were induced with N-ethyl-N-nitrosourea (ENU). The product of the Sl locus is Kit ligand (or Kitl; also known as mast cell growth factor, stem cell factor, and Steel factor), which is a member of the helical cytokine superfamily and is the ligand for the Kit receptor tyrosine kinase. Seven of the eight ENU-induced KitlSl alleles, of which five cause missense mutations, one causes a nonsense mutation and exon skipping, and one affects a splice site, were found to contain point mutations in Kitl. Interestingly, each of the five missense mutations affects residues that are within, or very near, conserved α-helical domains of Kitl. These ENU-induced mutants should provide important information on structural requirements for function of Kitl and other helical cytokines.

scholarly journals An Allelic Series of Mutations in the Kit ligand Gene of Mice. II. Effects of Ethylnitrosourea-Induced Kitl Point Mutations on Survival and Peripheral Blood Cells of KitlSteel Mice

Genetics ◽  
2002 ◽  
Vol 162 (1) ◽  
pp. 341-353 ◽  
Author(s):  
S Rajaraman ◽  
W S Davis ◽  
A Mahakali-Zama ◽  
H K Evans ◽  
L B Russell ◽  
...  
Keyword(s):  
Receptor Tyrosine Kinase ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Stem Cell Factor ◽  
Point Mutations ◽  
Peripheral Blood Cells ◽  
Allelic Series ◽  
Kit Ligand ◽  
Kit Receptor ◽  
Hypoplastic Anemia

Abstract The ligand for the Kit receptor tyrosine kinase is Kit ligand (Kitl; also known as mast cell growth factor, stem cell factor, and Steel factor), which is encoded at the Steel (Sl) locus of mice. Previous studies revealed that KitlSl mutations have semidominant effects; mild pigmentation defects and macrocytic, hypoplastic anemia occur in heterozygous mice, and more severe pigmentation defects and anemia occur in homozygotes. Lethality also occurs in mice homozygous for severe KitlSl mutations. We describe the effects of seven new N-ethyl-N-nitrosourea (ENU)-induced KitlSl mutations and two previously characterized severe KitlSl mutations on pigmentation, peripheral blood cells, and mouse survival. Mice heterozygous for each of the nine mutations had reduced coat pigmentation and macrocytosis of peripheral blood. In the case of some of these mutations, however, red blood cell (RBC) counts, hemoglobin concentrations, and hematocrits were normal in heterozygotes, even though homozygotes exhibited severely reduced RBC counts and lethality. In homozygous mice, the extent of anemia generally correlates with effects on viability for most KitlSl mutations; i.e., most mutations that cause lethality also cause a more severe anemia than that of mutations that allow viability. Interestingly, lethality and anemia were not directly correlated in the case of one KitlSl mutation.

Downregulation of c-kit (Stem Cell Factor Receptor) in Transformed Hematopoietic Precursor Cells by Stroma Cells

Blood ◽  
1999 ◽  
Vol 93 (2) ◽  
pp. 554-563 ◽  
Author(s):  
Christoph Heberlein ◽  
Jutta Friel ◽  
Christine Laker ◽  
Dorothee von Laer ◽  
Ulla Bergholz ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Line ◽  
Stem Cell Factor ◽  
Progenitor Cell ◽  
Receptor Expression ◽  
General Mechanism ◽  
Ligand Interaction ◽  
Kit Ligand ◽  
Kit Receptor ◽  
Progenitor Cell Line

Abstract We show a dramatic downregulation of the stem cell factor (SCF) receptor in different hematopoietic cell lines by murine stroma. Growth of the human erythroid/macrophage progenitor cell line TF-1 is dependent on granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3). However, TF-1 cells clone and proliferate equally well on stroma. Independent stroma-dependent TF-1 clones (TF-1S) were generated on MS-5 stroma. Growth of TF-1S and TF-1 cells on stroma still requires interaction between c-kit (SCF receptor) and its ligand SCF, because antibodies against c-kit inhibit growth to less than 2%. Surprisingly, c-kit receptor expression (RNA and protein) was downregulated by 2 to 3 orders of magnitude in TF-1S and TF-1 cells grown on stroma. This stroma-dependent regulation of the kit receptor in TF-1 was also observed on exposure to kit ligand-negative stroma, thus indicating the need for heterologous receptor ligand interaction. Removal of stroma induced upregulation by 2 to 4 orders of magnitude. Downregulation and upregulation of c-kit expression could also be shown for the megakaryocytic progenitor cell line M-07e and was comparable to that of TF-1, indicating that stroma-dependent regulation of c-kit is a general mechanism. Downregulation may be an economic way to compensate for the increased sensitivity of the c-kit/ligand interaction on stroma. The stroma-dependent c-kit regulation most likely occurs at the transcriptional level, because mechanisms, such as splicing, attenuation, differential promoter usage, or mRNA stability, could be excluded.

scholarly journals The rat c-kit ligand, stem cell factor, induces c-kit receptor-dependent mouse mast cell activation in vivo. Evidence that signaling through the c-kit receptor can induce expression of cellular function.

1992 ◽  
Vol 175 (1) ◽  
pp. 245-255 ◽  
Author(s):  
B K Wershil ◽  
M Tsai ◽  
E N Geissler ◽  
K M Zsebo ◽  
S J Galli
Keyword(s):  
Mast Cell ◽  
Stem Cell ◽  
Mast Cells ◽  
Stem Cell Factor ◽  
Cell Activation ◽  
Mast Cell Activation ◽  
Tyrosine Kinase Receptor ◽  
Kit Ligand ◽  
Kit Receptor

Interactions between products of the mouse W locus, which encodes the c-kit tyrosine kinase receptor, and the Sl locus, which encodes a ligand for c-kit receptor, which we have designated stem cell factor (SCF), have a critical role in the development of mast cells. Mice homozygous for mutations at either locus exhibit several phenotypic abnormalities including a virtual absence of mast cells. Moreover, the c-kit ligand SCF can induce the proliferation and maturation of normal mast cells in vitro or in vivo, and also can result in repair of the mast cell deficiency of Sl/Sld mice in vivo. We now report that administration of SCF intradermally in vivo results in dermal mast cell activation and a mast cell-dependent acute inflammatory response. This effect is c-kit receptor dependent, in that it is not observed when SCF is administered to mice containing dermal mast cells expressing functionally inactive c-kit receptors, is observed with both glycosylated and nonglycosylated forms of SCF, and occurs at doses of SCF at least 10-fold lower on a molar basis than the minimally effective dose of the classical dermal mast cell-activating agent substance P. These findings represent the first demonstration in vivo that a c-kit ligand can result in the functional activation of any cellular lineage expressing the c-kit receptor, and suggest that interactions between the c-kit receptor and its ligand may influence mast cell biology through complex effects on proliferation, maturation, and function.

scholarly journals The Wiskott-Aldrich syndrome and X-linked congenital thrombocytopenia are caused by mutations of the same gene

Blood ◽  
1995 ◽  
Vol 86 (10) ◽  
pp. 3797-3804 ◽  
Author(s):  
Q Zhu ◽  
M Zhang ◽  
RM Blaese ◽  
JM Derry ◽  
A Junker ◽  
...  
Keyword(s):  
Clinical Symptoms ◽  
Point Mutations ◽  
Gene Mutations ◽  
Exon Skipping ◽  
Splice Site Mutation ◽  
Missense Mutations ◽  
Site Mutation ◽  
Exon 2 ◽  
Wiskott Aldrich Syndrome ◽  
Was Gene

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia, small platelets, eczema, recurrent infections, and immunodeficiency. Besides the classic WAS phenotype, there is a group of patients with congenital X-linked thrombocytopenia (XLT) who have small platelets but only transient eczema, if any, and minimal immune deficiency. Because the gene responsible for WAS has been sequenced, it was possible to correlate the WAS phenotypes with WAS gene mutations. Using a fingerprinting screening technique, we determined the approximate location of the mutation in 13 unrelated WAS patients with mild to severe clinical symptoms. Direct sequence analysis of cDNA and genomic DNA obtained from patient-derived cell lines showed 12 unique mutations distributed throughout the WAS gene, including insertions, deletions, and point mutations resulting in amino acid substitutions, termination, exon skipping, or splicing defects. Of 4 unrelated patients with the XLT phenotype, 3 had missense mutations affecting exon 2 and 1 had a splice-site mutation affecting exon 9. Patients with classic WAS had more complex mutations, resulting in termination codons, frameshift, and early termination. These findings provide direct evidence that XLT and WAS are caused by mutations of the same gene and suggest that severe clinical phenotypes are associated with complex mutations.

JAK2 is associated with the c-kit proto-oncogene product and is phosphorylated in response to stem cell factor

Blood ◽  
1996 ◽  
Vol 87 (9) ◽  
pp. 3688-3693 ◽  
Author(s):  
SR Weiler ◽  
S Mou ◽  
CS DeBerry ◽  
JR Keller ◽  
FW Ruscetti ◽  
...  
Keyword(s):  
Stem Cell ◽  
Tyrosine Phosphorylation ◽  
Receptor Tyrosine Kinase ◽  
Antisense Oligonucleotides ◽  
Stem Cell Factor ◽  
Signal Transduction Pathway ◽  
Transduction Pathway ◽  
Kinase C ◽  
Kit Receptor ◽  
Normal Human

Stem cell factor (SCF) is a hematopoietic growth factor that interacts with the receptor tyrosine kinase, c-kit. We have found that SCF- stimulates rapid and transient tyrosine phosphorylation of JAK2 in human and murine cell lines, as well as in normal human progenitor cells. JAK2 and c-kit were associated in unstimulated cells with further recruitment of JAK2 to the c-kit receptor complex after SCF stimulation. Treatment of cells with JAK2 antisense oligonucleotides resulted in a 46% decrease in SCF-induced proliferation. These data demonstrate that SCF induces tyrosine phosphorylation of JAK2 and suggest that JAK2 is a component of the SCF signal transduction pathway.

Additive effect of mouse genetic background and mutation ofMITF gene on decrease of skin mast cells

Blood ◽  
2003 ◽  
Vol 101 (4) ◽  
pp. 1344-1350 ◽  
Author(s):  
Eiichi Morii ◽  
Keisuke Oboki ◽  
Tomoko Jippo ◽  
Yukihiko Kitamura
Keyword(s):  
Transcription Factor ◽  
Mast Cells ◽  
Receptor Tyrosine Kinase ◽  
Genetic Background ◽  
Leucine Zipper ◽  
Basic Helix Loop Helix ◽  
Kit Ligand ◽  
Helix Loop Helix ◽  
Kit Receptor ◽  
Mouse Genetic

The mi transcription factor (MITF) is a basic-helix-loop-helix leucine zipper transcription factor and is encoded by mi locus. The mi/mi mutant mice showed a significant decrease of skin mast cells in C57BL/6 (B6) genetic background but not in WB genetic background. Kit ligand (KitL) is the most important growth factor for development of mast cells, and the decrease of skin mast cells in B6-mi/mi mice was attributable to the reduced expression of c-kit receptor tyrosine kinase (KIT) that is a receptor for KitL. However, the expression level of KIT in WB-mi/mi mast cells was comparable with that of B6-mi/mi mast cells, suggesting that a factor compensating the reduced expression of KIT was present in WB-mi/mi mice. By linkage analysis, such a factor was mapped on chromosome 10. The mapped position was closely located to the KitL locus. Two alternative spliced forms are known in KitL mRNA: KL-1 and KL-2. Soluble KitL, which is important for development of skin mast cells, is produced more efficiently from KL-1 mRNA than from KL-2 mRNA. The KL-1/KL-2 ratio was higher in WB-mi/mi than in B6-mi/mi mice, suggesting that the larger amount of soluble KitL may compensate for the reduced expression of KIT in WB-mi/mi mice.

scholarly journals Constitutively activating mutations of c-kit receptor tyrosine kinase confer factor-independent growth and tumorigenicity of factor-dependent hematopoietic cell lines

Blood ◽  
1995 ◽  
Vol 85 (3) ◽  
pp. 790-798 ◽  
Author(s):  
H Kitayama ◽  
Y Kanakura ◽  
T Furitsu ◽  
T Tsujimura ◽  
K Oritani ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Nude Mice ◽  
Receptor Tyrosine Kinase ◽  
Point Mutations ◽  
Hematologic Malignancies ◽  
Retroviral Vectors ◽  
Independent Manner ◽  
Constitutive Activation ◽  
Activating Mutations ◽  
Kit Receptor

The c-kit receptor tyrosine kinase (KIT) is activated upon ligand binding, thereby leading to a variety of signaling events that play a fundamental role in hematopoiesis. In addition to ligand-dependent activation, we have previously shown that KIT is constitutively activated in a ligand-independent manner by two point mutations, Val- 559-->Gly (G559) mutation in the juxtamembrane domain and Asp-814-->Val (V814) mutation in the phosphotransferase domain. To investigate the biochemical consequence and biologic significance of these mutations, retroviral vectors encoding KITG559 or KITV814 were introduced into murine pro-B-type Ba/F3 cells and myeloid FDC-P1 cells, both of which require interleukin-3 (IL-3) for their growth and survival. In the cells, KITG559 or KITV814 were found to be constitutively phophorylated on tyrosine in the absence of stem cell factor (SCF) that is a ligand for KIT. Chemical cross-linking analysis showed that a substantial fraction of the phosphorylated KITG559 underwent dimerization even in the absence of SCF, whereas the phosphorylated KITV814 did not, suggesting the distinct mechanisms underlying constitutive activation of KIT by G559 and V814 mutations. Furthermore, the cells expressing either KITG559 or KITV814 were found to show a factor-independent growth, whereas the cells expressing wild-type KIT (KITWT) proliferated in response to SCF as well as IL-3. Moreover, subcutaneous injection of Ba/F3 cells expressing KITG559 or KITV814 into nude mice resulted in production of large tumors at all sites of the injection within 2 weeks, and all nude mice quickly succumbed to leukemia and died. These results suggest that, although the mechanisms underlying constitutive activation of KITG559 or KITV814 may be different, both of the activating mutations have a function to induce a factor-independent and tumorigenic phenotype. Also, the data of this study raise the possibility that the constitutively activating mutations of c-kit may play a causal role in development of hematologic malignancies.

Downregulation of c-kit (Stem Cell Factor Receptor) in Transformed Hematopoietic Precursor Cells by Stroma Cells

Blood ◽  
1999 ◽  
Vol 93 (2) ◽  
pp. 554-563
Author(s):  
Christoph Heberlein ◽  
Jutta Friel ◽  
Christine Laker ◽  
Dorothee von Laer ◽  
Ulla Bergholz ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Line ◽  
Stem Cell Factor ◽  
Progenitor Cell ◽  
Receptor Expression ◽  
General Mechanism ◽  
Ligand Interaction ◽  
Kit Ligand ◽  
Kit Receptor ◽  
Progenitor Cell Line

We show a dramatic downregulation of the stem cell factor (SCF) receptor in different hematopoietic cell lines by murine stroma. Growth of the human erythroid/macrophage progenitor cell line TF-1 is dependent on granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3). However, TF-1 cells clone and proliferate equally well on stroma. Independent stroma-dependent TF-1 clones (TF-1S) were generated on MS-5 stroma. Growth of TF-1S and TF-1 cells on stroma still requires interaction between c-kit (SCF receptor) and its ligand SCF, because antibodies against c-kit inhibit growth to less than 2%. Surprisingly, c-kit receptor expression (RNA and protein) was downregulated by 2 to 3 orders of magnitude in TF-1S and TF-1 cells grown on stroma. This stroma-dependent regulation of the kit receptor in TF-1 was also observed on exposure to kit ligand-negative stroma, thus indicating the need for heterologous receptor ligand interaction. Removal of stroma induced upregulation by 2 to 4 orders of magnitude. Downregulation and upregulation of c-kit expression could also be shown for the megakaryocytic progenitor cell line M-07e and was comparable to that of TF-1, indicating that stroma-dependent regulation of c-kit is a general mechanism. Downregulation may be an economic way to compensate for the increased sensitivity of the c-kit/ligand interaction on stroma. The stroma-dependent c-kit regulation most likely occurs at the transcriptional level, because mechanisms, such as splicing, attenuation, differential promoter usage, or mRNA stability, could be excluded.

Stem cell factor induces outgrowth of c-kit-positive neurites and supports the survival of c-kit-positive neurons in dorsal root ganglia of mouse embryos

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 49-56 ◽  
Author(s):  
T. Hirata ◽  
E. Morii ◽  
M. Morimoto ◽  
T. Kasugai ◽  
T. Tsujimura ◽  
...  
Keyword(s):  
Stem Cell ◽  
Tyrosine Kinase ◽  
Neurite Outgrowth ◽  
Dorsal Root Ganglia ◽  
Receptor Tyrosine Kinase ◽  
Stem Cell Factor ◽  
Dorsal Root ◽  
Mouse Embryos ◽  
Kit Receptor ◽  
Vitro Effect

The c-kit receptor tyrosine kinase is highly expressed by about 10% of the neurons in the dorsal root ganglia (DRGs) of mouse embryos. We investigated the in vitro effect of stem cell factor (SCF), the ligand for c-kit receptor, on DRGs. Recombinant murine SCF (rmSCF) induced the outgrowth of c-kit-positive neurites from DRGs of normal (+/+) embryos. The effect of SCF was dose dependent and completely abolished by anti-c-kit ACK2 monoclonal antibody (mAb). Some neurites whose outgrowth was induced by nerve growth factor (NGF) were c-kit-positive, but anti-NGF mAb did not inhibit the rmSCF-induced neurite outgrowth. rmSCF did not induce neurite outgrowth from DRGs of W/W embryos that did not express c-kit receptors on the cell surface and of W42/W42 mutant embryos that expressed c-kit receptors without tyrosine kinase activity. rmSCF also had a trophic effect on c-kit-positive neurons in the culture of dissociated DRG cells. Most c-kit-positive neurons appeared to respond to NGF as well, and the SCF-responsive subpopulation represented about 10% of NGF-responsive neurons. rmSCF did not support the survival of DRG neurons from embryos of W/W and W42/W42 genotypes. These results suggest that the stimulus through the c-kit receptor tyrosine kinase has an important role in development of the peripheral nervous system.

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