Involvement of MITF-A, an alternative isoform of mi transcription factor, on the expression of tryptase gene in human mast cells.
Mast cells play a central role in the initiation and development of allergic diseases through release of various mediators. Tryptase has been known to be a key mediator in mast cell-mediated inflammatory reactions. In the present study, we investigated whether the transcription of tryptase gene in human mast cells was induced by microphthalmia (mi)-associated transcription factor (MITF). We observed that the human CD34+ progenitor-derived cultured mast cells and human mast cell line HMC-1 expressed strongly the transcripts of tryptase-beta1 and MITF-A, which is a MITF alterative splicing isoform. The transcriptional activity of tryptase gene was specifically higher in HMC-1 cells compared to the tryptase-negative cells. Using mutant constructs of tryptase promoter, we observed that two E-box (CANNTG) motifs including between -817 to -715 and -421 to -202 are able to involve in the transactivation of tryptase gene by MITF-A. In addition, the binding of these motifs-containing oligonucleotides to MITF proteins was detectable by EMGA using the nuclear extracts of HMC-1 cells and anti-MITF mAb. The overexpression of MITF-A elevated tryptase production by HMC-1 cells, while the introduction of specific siRNA against MITF attenuated the expression and enzymatic activity of tryptase. These data suggest that MITF might play a role in regulating the transcription of tryptase gene in human mast cells.
Department of Immunology and Institute of Medical Sciences, Chonbuk National University Medical School Jeonju 561-756, Korea.
Sun-Hee
SH
Lee
Jeong-Heon
JH
Lee
Jeong-Heon
JH
Lee
Dae-Ki
DK
Kim
D045744:Cell Line, Tumor; D024721:E-Box Elements / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007946:Leukemia, Mast-Cell; D008407:Mast Cells / Q000378:metabolism*; D051739:Microphthalmia-Associated Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D015533:Transcriptional Activation; D053802:Tryptases / Q000235:genetics / Q000378:metabolism*
C497234:MITF protein, human; D051739:Microphthalmia-Associated Transcription Factor; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D053802:Tryptases