Regulation of mouse mast cell protease 6 gene expression by transcription factor encoded by the mi locus.
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). Because the expression of the mouse mast cell protease 6 (MMCP-6) gene is remarkably reduced in mast cells of mi/mi mutant mice, we investigated the effect of MITF on the transcription of the MMCP-6 gene. First, we introduced the normal (+) MITF cDNA into mi/mi cultured mast cells using the retroviral vector. Overexpression of +-MITF but not mi-MITF normalized the expression of the MMCP-6 gene, indicating the involvement of +-MITF in the MMCP-6 gene transactivation. Second, we analyzed the promoter of the MMCP-6 gene by the transient cotransfection assay. The luciferase construct under the control of the MMCP-6 promoter and the cDNA encoding +-MITF or mi-MITF were cotransfected into NIH/ 3T3 fibroblasts. The coexpression of +-MITF but not mi-MITF increased the luciferase activity 10-fold. We found a CACATG and a CATCTG motif in the MMCP-6 promoter, both of which are generally recognized by bHLH-Zip-type transcription factors. We also found a GACCTG motif that was strongly bound by +-MITF. These three motifs were necessary for the 10-fold transactivation ability of the MMCP-6 promoter by +-MITF. Mutations of each motif significantly reduced the transactivation, suggesting that +-MITF directly transactivated the MMCP-6 gene through these three motifs.
Morii
E
E
Department of Pathology, Osaka University Medical School, Japan.
Tsujimura
T
T
Jippo
T
T
Hashimoto
K
K
Takebayashi
K
K
Tsujino
K
K
Nomura
S
S
Yamamoto
M
M
Kitamura
Y
Y
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D004790:Enzyme Induction; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D008407:Mast Cells / Q000201:enzymology*; D051379:Mice; D008817:Mice, Mutant Strains; D051739:Microphthalmia-Associated Transcription Factor; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D016415:Sequence Alignment; D012697:Serine Endopeptidases / Q000096:biosynthesis* / Q000235:genetics; D014157:Transcription Factors; D015533:Transcriptional Activation; D014162:Transfection; D053802:Tryptases
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C509190:Tpsb2 protein, mouse; D014157:Transcription Factors; D012697:Serine Endopeptidases; C509222:Tpsab1 protein, mouse; D053802:Tryptases