Exp Mol Med.  2010 May;42(5):366-375. 10.3858/emm.2010.42.5.038.

Involvement of MITF-A, an alternative isoform of mi transcription factor, on the expression of tryptase gene in human mast cells

• Lee SH
• Lee JH
• Lee YM
• Kim DK

• KMID: 946636
• DOI: http://doi.org/10.3858/emm.2010.42.5.038

Abstract

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.

Keyword

alternative splicing; gene expression regulation; mast cells; microphthalmia-associated transcription factor; tryptases