Involvement of the SgIGSF plasma membrane-spanning molecule in adhesion and survival of mast cells

SgIGSF是新近发现的一种黏附分子，小眼球转录因子(MITF)对其在肥大细胞中的表达起重要作用。由于Tg突变等位基因实际上是MITF基因的零突变，来自(Wb x C57BL/6)F1(F1)-TG/TG小鼠的培养肥大细胞(CMCs)不表达SgIGSF，而来自F1野生型(/)小鼠的CMCs大量表达SgIGSF。与NIH/3T3成纤维细胞共培养时，F1-TG/TGCMCs与NIH/3T3成纤维细胞的粘附性差，骨髓来源的肥大细胞(BMMCs)对急性细菌性腹膜炎有治疗作用。为了发挥这一作用，骨髓基质细胞需要从腹膜腔稳定肠系膜。采用肥大细胞缺陷F1-W/W、ν[c-kit受体酪氨酸激酶(KIT)突变体]、F1-S1/Sl^d[KIT配体干细胞因子突变体]和F1-TG/TG小鼠，观察BMMC与肠系膜细胞的相互作用。检测3个参数：(1)经腹腔注射肥大细胞缺陷小鼠5周后在肠系膜形成的BMMC数；(2)黏附于肠系膜间皮细胞的数目；(3)在两者共同培养3h和18h时，穿过肠系膜间皮细胞单层的数目。在肥大细胞缺陷的F1-W/W、ν小鼠体内注射后，F1-TG/TG CMCs在腹膜腔内的存活率较低。通过逆转录病毒转染法和转基因表达法在TG/TGCMCs中异位表达了SgIGSF。与对照F1-TG/TG CMCs相比，TG/TG CMCs不仅对NIH/3T3成纤维细胞有更好的黏附能力，而且在腹膜内的存活能力也更强。这些结果表明，SgIGSF在肥大细胞与肥大细胞的黏附和存活中起着重要的作用，SgIGSF和KIT在跨肠系膜间皮细胞的迁移中具有明显的作用。

SgIGSF (Spermatogenic Immunoglobulin Superfamily) is a recently identified adhesion molecule, and the microphthalmia transcription factor (MITF) was essential for its expression in mast cells. Since the tg mutant allele is practically a null mutation of the MITF gene, cultured mast cells (CMCs) derived from (WB x C57BL/6)F_1 (F_1)-tg/tg mice did not express SgIGSF whereas CMCs from F_1-wild-type (+/+) mice expressed it abundantly. When cocultured with NIH/3T3 fibroblasts, F_1-tg/tg CMCs showed poor adhesion to NIH/3T3 fibroblasts.Intraperitoneal injection of bone marrow-derived mast cells (BMMCs) has therapeutic efficacy against acute bacterial peritonitis. For this role, BMMCs need to settle down the mesentery from the peritoneal cavity. Interaction between BMMCs and the mesentery was examined by using mast cell deficient F_1-W/W^ν [c-kit receptor tyrosine kinase (KIT) mutant], F_1-Sl/Sl^d [KIT ligand stem cell factor (SCF) mutant] and F_1-tg/tg mice. Three parameters were measured : the number of BMMCs (1) developed in the mesentery 5 weeks after intraperitoneal injection into mast cell deficient mice, (2) adhered to mesenteric mesothelial cells, and (3) transmigrated across the mesenteric mesothelial cell monolayer when coculturing both cells for 3 and 18 hours, respectively. When injected intraperitoneally, F_1-tg/tg CMCs showed poor survival in the peritoneal cavity of mast cell-deficient F_1-W/W^ν mice. SgIGSF was expressed in tg/tg CMCs ectopically through retroviral transfection and through expression of a transgene. The resulting tg/tg CMCs showed not only a better adhesion to NIH/3T3 fibroblasts but also a better survival in the peritoneal cavity than control F_1-tg/tg CMCs.These results showed that SgIGSF played a significant role in mast-cell adhesion and survival, and that SgIGSF and KIT had distinct roles in transmigration across mesenteric mesothelial cells.