Independent influence of strain difference and mi transcription factor on the expression of mouse mast cell chymases

Expression of mouse mast cell protease (mMCP) genes was examined with parti cular attention to the transactivation effect of mi transcription factor (M ITF) and the expression differences between C57BL/6 (B6) and WE strains. We had reported the enhancing effect of MITE on the expression of mMCP-4, -5, and -6 genes in cultured mast cells (CMCs) of BG strain, and in the presen t study we demonstrated the enhancing effect on the expression of mMCP-2 an d -9 genes as well. The enhancing effect of MITF on the expression of mMCP- 2, -4, -5, -6, and -9 genes was also detected in CMCs of the WE strain. The regulation of mMCP-2, -4, and -9 genes was localized to a specific promote r element (CANNTG) which was recognized and bound by MITE and which was con served between the BG and WB strains. On the other hand, the expression of mMCP-2, -4, and -9 genes was smaller in CMCs of the BG strain when compared to their expression in CMCs of the WB strain. Although mMCP-5 is a chymase as mMCP-2, -4, and -9, and genes encoding all of the chymases are located on chromosome 14, the mMCP-5 gene was regulated in a manner distinct from m MCP-2, -4, and -9 genes.