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.
ARTICLES|
August 15, 1996
Involvement of transcription factor encoded by the mi locus in the expression of c-kit receptor tyrosine kinase in cultured mast cells of mice
T Tsujimura,
T Tsujimura
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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E Morii,
E Morii
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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M Nozaki,
M Nozaki
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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K Hashimoto,
K Hashimoto
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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Y Moriyama,
Y Moriyama
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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K Takebayashi,
K Takebayashi
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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T Kondo,
T Kondo
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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Y Kanakura,
Y Kanakura
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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Y Kitamura
Y Kitamura
Department of Pathology, Medical School, Osaka University, Suita, Japan.
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Blood (1996) 88 (4): 1225–1233.
Citation
T Tsujimura, E Morii, M Nozaki, K Hashimoto, Y Moriyama, K Takebayashi, T Kondo, Y Kanakura, Y Kitamura; Involvement of transcription factor encoded by the mi locus in the expression of c-kit receptor tyrosine kinase in cultured mast cells of mice. Blood 1996; 88 (4): 1225–1233. doi: https://doi.org/10.1182/blood.V88.4.1225.bloodjournal8841225
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