Activation of MAP kinases, pp90rsk and pp70-S6 kinases in mouse mast cells by signaling through the c-kit receptor tyrosine kinase or FcεRI: rapamycin inhibits activation of pp70-S6 kinase and proliferation in mouse mast cells

The mi locus of mice encodes a member of the basic-helix-loop-helix- leucine zipper (bHLH-Zip) protein family of transcription factors (hereafter called MITF). Cultured mast cells of mi/mi genotype (mi/mi CMCs) did not normally respond to stem cell factor (SCF), a ligand for the c-kit receptor tyrosine kinase. The poor response of mi/mi CMCs to SCF was attributed to the deficient expression of c-kit both the mRNA and protein levels. The purpose of the present study is to investigate the effect of MITF on the transcription of the c-kit gene. First, we introduced cDNA encoding normal (+) MITF or mutant (mi) MITF into mi/mi CMCs using the retroviral vector. Overexpression of (+)-MITF but not mi- MITF normalized the expression of the c-kit and the poor response of mi/mi CMCs to SCF, indicating the involvement of (+)-MITF in the c-kit gene transactivation. Second, we analyzed the promoter of the c-kit gene. Three CANNTG motifs recognized by bHLH-Zip-type transcription factors were conserved between the mouse and human c-kit promoters. Among these three CANNTG motifs, only the CACCTG motif (nt -356 to - 351) was specifically bound by (+)-MITF. When the luciferase gene under the control of the c-kit promoter was contransfected into NIH/3T3 fibroblasts with cDNA encoding (+)-MITF or mi-MITF, the luciferase activity significantly increased only when (+)-MITF cDNA was cotransfected. The deletion of the promoter region containing the CACCTG motif or the mutation of the CACCTG to CTCCAG abolished the transactivation effect of (+)-MITF, indicating that (+)-MITF transactivated the c-kit gene through the CACCTG motif. When the luciferase gene under the control of the c-kit promoter was introduced into the FMA3 mastocytoma and FEC-P1 myeloid cell lines, remarkable luciferase activity was observed only in FMA3 cells. Thus, the involvement of (+)-MITF in the c-kit transactivation appeared to be specific to the mast cell lineage.

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Substrate phosphorylation specificity of the human c-kit receptor tyrosine kinase.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)54869-9 ◽

1991 ◽

Vol 266 (30) ◽

pp. 19908-19916 ◽

Cited By ~ 2

Author(s):

R. Herbst ◽

R. Lammers ◽

J. Schlessinger ◽

A. Ullrich

Keyword(s):

Tyrosine Kinase ◽

Receptor Tyrosine Kinase ◽

Kit Receptor ◽

Substrate Phosphorylation

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Monoclonal Antibodies Mimic Insulin Activation of Ribosomal Protein S6 Kinase without Activation of Insulin Receptor Tyrosine Kinase

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)47250-5 ◽

1989 ◽

Vol 264 (32) ◽

pp. 18951-18959 ◽

Cited By ~ 2

Author(s):

C K Sung ◽

B A Maddux ◽

D M Hawley ◽

I D Goldfine

Keyword(s):

Monoclonal Antibodies ◽

Tyrosine Kinase ◽

Ribosomal Protein ◽

Insulin Receptor ◽

Receptor Tyrosine Kinase ◽

S6 Kinase ◽

Insulin Receptor Tyrosine Kinase ◽

Ribosomal Protein S6 ◽

Ribosomal Protein S6 Kinase

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Fer Kinase Is Required for Sustained p38 Kinase Activation and Maximal Chemotaxis of Activated Mast Cells

Molecular and Cellular Biology ◽

10.1128/mcb.22.18.6363-6374.2002 ◽

2002 ◽

Vol 22 (18) ◽

pp. 6363-6374 ◽

Cited By ~ 38

Author(s):

Andrew W. B. Craig ◽

Peter A. Greer

Keyword(s):

Mast Cells ◽

Map Kinases ◽

Immunoglobulin E ◽

P38 Map Kinase ◽

Mast Cell Activation ◽

Receptor Protein ◽

Mouse Bone Marrow ◽

P38 Kinase ◽

Kinase Activation ◽

Kit Receptor

ABSTRACT Mast cells play important roles in inflammation and immunity and express the high-affinity immunoglobulin E receptor (FcεRI) and the receptor protein-tyrosine kinase Kit. Aggregation of FcεRI via antigen binding elicits signals leading to the release of preformed inflammatory mediators as well as de novo-synthesized lipid mediators and cytokines and to elevated cell adhesion and migration. Here, we report that in mouse bone marrow-derived mast cells, Fer kinase is activated downstream of activated FcεRI and activated Kit receptor, and this activation is abolished in cells homozygous for a kinase-inactivating mutation in Fer (fer DR/DR ). Interestingly, the highly related Fps/Fes kinase is also activated upon FcεRI aggregation. This report represents the first description of a common signaling pathway activating Fer and Fps/Fes. While Fer-deficient cells showed similar activation of the Erk mitogen-activated protein (MAP) kinases, p38 MAP kinase activation was less sustained than that in wild-type cells. Although no major defects were observed in degranulation, leukotriene biosynthesis, and cytokine secretion, Fer-deficient cells displayed increased adhesion and decreased motility upon activation of FcεRI and the Kit receptor. The restoration of Fer kinase activity in fer DR/DR mast cells resulted in prolonged p38 kinase activation and increased antigen-mediated cell migration of sensitized mast cells. Thus, Fer is required for maximal p38 kinase activation to promote the chemotaxis of activated mast cells. Further studies with mast cells derived from fps/fes-deficient mice will be required to provide insight into the role of Fps/Fes in mast cell activation.

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