Cooperative Regulation of the Mucosal Mast Cell–Specific Protease Genes <i>Mcpt1</i> and <i>Mcpt2</i> by GATA and Smad Transcription Factors

Abstract

Mouse mast cell proteases (mMCP)-1 and -2 are specifically expressed in mucosal mast cells (MCs). However, the transcriptional regulation mechanism of the <i>Mcpt1</i> and <i>Mcpt2</i> genes induced in mucosal MCs is largely unknown. In the current study, we found that TGF-β stimulation drastically induced upregulation of <i>Mcpt1</i> and <i>Mcpt2</i> mRNA in mouse bone marrow-derived MCs (BMMCs). TGF-β-induced expression of <i>Mcpt1</i> and <i>Mcpt2</i> was markedly suppressed by transfection with small interfering RNA targeting <i>Smad2</i> or <i>Smad4</i> and moderately reduced by <i>Smad3</i> small interfering RNA. We next examined the roles of the hematopoietic cell-specific transcription factors GATA1 and GATA2 in the expression of <i>Mcpt1</i> and <i>Mcpt2</i> and demonstrated that knockdown of GATA1 and GATA2 reduced the mRNA levels of <i>Mcpt1</i> and <i>Mcpt2</i> 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 <i>Mcpt1</i> and <i>Mcpt2</i> 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 <i>Mcpt1</i> and <i>Mcpt2</i> genes in mucosal MCs.