MITF and SgIGSF: an essential transcription factor and its target adhesion molecule for development and survival of mast cells.

MITF transcription factor is not produced in mutant mice of WBB6F1-Mitf(mi-vga9/Mitf(mi-vga9). When bone marrow cells of normal WBB6F1-+/+ micewere transplanted to the irradiated WBB6F1-KitW/KitW-v mice, which are genetically mast cell deficient, erythrocytes, neutrophils, macrophages, B cells and T cells of the donor origin developed in the recipients. On the other hand, when bone marrow cells of WBB6F1-Mitf(mi-vga9/Mitf(mi-vga9) mice were transplanted to similarly irradiated WBB6F1-KitW/KitW-v mice, erythrocytes, neutrophils, macrophages, B cells and T cells of the donor origin developed but mast cells never appeared. To identify the targets of MITF, we elaborated a subtracted cDNA library between cultured mast cells (CMCs) derived from +/+ mice and CMCs from MITF mutant mice. We obtained a clone encoding SgIGSF, which was expressed on the adhesion surface of +/+ CMCs attaching to fibroblasts. CMCs of WBB6F1-Mitf(mi-vga9/ Mitf(mi-vga9) mice did not express SgIGSF, did not attach to fibroblasts and did not survive in the peritoneal cavity of WBB6F1-KitW/KitW-v mice. When MITF or SgIGSF cDNA was transfected to WBB6F1-Mitf(mi-vga9/Mitf(mi-vga9) CMCs, they attached to fibroblasts and showed an improved survival in the peritoneal cavity of WBB6F1-KitW/KitW-v mice. MITF and SgIGSF appeared essential for the development and survival of mast cells in tissues of adult WBB6F1-KitW/KitW-v mice.