Cooperative Regulation of the Mucosal Mast Cell-Specific Protease Genes and by GATA and Smad Transcription Factors.

Mouse mast cell proteases (mMCP)-1 and -2 are specifically expressed in mucosal mast cells (MCs). However, the transcriptional regulation mechanism of the and genes induced in mucosal MCs is largely unknown. In the current study, we found that TGF-β stimulation drastically induced upregulation of and mRNA in mouse bone marrow-derived MCs (BMMCs). TGF-β-induced expression of and was markedly suppressed by transfection with small interfering RNA targeting or and moderately reduced by small interfering RNA. We next examined the roles of the hematopoietic cell-specific transcription factors GATA1 and GATA2 in the expression of and and demonstrated that knockdown of GATA1 and GATA2 reduced the mRNA levels of and in BMMCs. The recruitment of GATA2 and acetylation of histone H4 of the highly conserved GATA-Smad motifs, which were localized in the distal regions of the and genes, were markedly increased by TGF-β stimulation, whereas the level of GATA2 binding to the proximal GATA motif was not affected by TGF-β. A reporter assay showed that TGF-β stimulation upregulated GATA2-mediated transactivation activity in a GATA-Smad motif-dependent manner. We also observed that GATA2 and Smad4 interacted in TGF-β-stimulated BMMCs via immunoprecipitation and Western blotting analysis. Taken together, these results demonstrate that TGF-β induced mMCP-1 and -2 expression by accelerating the recruitment of GATA2 to the proximal regions of the and genes in mucosal MCs.