Synergy of PEBP2/CBF with mi transcription factor (MITF) for transactivation of mouse mast cell protease 6 gene

Abstract

The mi locus encodes a member of the basic-helix-loop-helix-leucine zipper (bHLH-Zip) protein family of transcription factors (hereafter called MITF), Although the bHLH-Zip family transcription factors generally recognize and bind CANNTG motifs, the expression of mouse mast cell protease 6 (MMCP-6) gene is regulated by MITF through the (G) under bar ACCTG motif in the promoter region. The GACC<(TG)under bar> motif was partly overlapped the <(TG)under bar>TGGTC sequence, which was bound by polyomavirus enhancer binding protein 2 (PEBP2), In the present study, the effect of PEBP2 on the expression of MMCP-6 gene was examined, PEBP2 that is composed of alpha and beta subunits was expressed by mast cell Lines and cultured mast cells derived from spleen, The overexpression of dominant negative PEBP2 cDNA reduced the expression of MMCP-6. Moreover, the simultaneous transfection of the plasmid containing MITF cDNA and the plasmid containing PEBP2 cDNA increased the MMCP-6 promoter activity, For the synergistic action of PEBP2 and MITF, the intact GACC<(TG)under bar> and <(TG)under bar>TGGTC motifs were prerequisite. The PEBP2 alpha B1 mutant which lacked the region downstream from the Runt domain did not bind MITF and lost the synergistic function. These results indicated that PEBP2 and MITF synergistically transactiva