Ogasawara T, Murakami M, Suzuki-Nishimura T, Uchida M K, Kudo I
Department of Molecular Pharmacology, Meiji College of Pharmacy, Nozawa, Setagaya-ku, Tokyo, Japan.
J Immunol. 1997 Jan 1;158(1):393-404.
Polycationic mast cell activators, such as compound 48/80 and substance P, have been reported to activate connective tissue-type mast cells specifically by interacting directly with the Gi family of trimeric GTP-binding protein. We now demonstrate that mouse bone marrow-derived mast cells (BMMC) developed in IL-3, an immature mast cell population lacking responsiveness to the Gi-coupled polycationic mast cell activators, underwent maturation toward a connective tissue-type mast cells-like phenotype that responded to polycationic compounds after only 4 to 6 days of coculture with Swiss 3T3 fibroblasts in concert with recombinant soluble c-kit ligand (KL), whereas 3T3 or KL alone was insufficient to mediate this process. Under optimal conditions, cocultured BMMC released approximately 30% beta-hexosaminidase and generated approximately 1 ng of PGD2/10(6) cells within a few minutes in response to compound 48/80 or substance P. Furthermore, these cells expressed cytokines, such as IL-1beta and IL-6, and PG endoperoxide synthase-2 1 to 4 h after stimulation with compound 48/80 or substance P. All these responses were suppressed effectively by pertussis toxin, implicating functional Gi coupling. Regardless of the remarkable change in polycationic compound sensitivity, there was only a minimal change in the constitutive expression of Gi3 alpha after coculture. These results together with the observation that before coculture BMMC responded to thrombin through its Gi-coupled receptor suggest that the alteration in a certain step(s) distinct from the level of Gi3 alpha protein expression is important for the acquisition of responsiveness to the polycationic compounds by the synergistic action of KL and 3T3 fibroblast-derived factor. Several lines of evidence have revealed that 3T3-derived factor appears to differ from the known cytokines, prostanoids, and adhesion molecules and is a labile soluble substance.
据报道，多阳离子肥大细胞激活剂，如化合物48/80和P物质，通过直接与三聚体GTP结合蛋白的Gi家族相互作用，特异性地激活结缔组织型肥大细胞。我们现在证明，在白细胞介素-3中发育的小鼠骨髓来源的肥大细胞（BMMC），这是一种对Gi偶联的多阳离子肥大细胞激活剂无反应的未成熟肥大细胞群体，在与瑞士3T3成纤维细胞和重组可溶性c-kit配体（KL）共培养仅4至6天后，就向结缔组织型肥大细胞样表型成熟，对多阳离子化合物有反应，而单独的3T3或KL不足以介导这一过程。在最佳条件下，共培养的BMMC在几分钟内对化合物48/80或P物质释放约30%的β-己糖胺酶，并产生约1 ng的PGD2/10(6)细胞。此外，这些细胞在受到化合物48/80或P物质刺激后1至4小时表达细胞因子，如白细胞介素-1β和白细胞介素-6，以及PG内过氧化物合酶-2。所有这些反应都被百日咳毒素有效抑制，这表明存在功能性Gi偶联。尽管多阳离子化合物敏感性有显著变化，但共培养后Gi3α的组成性表达仅有最小变化。这些结果以及共培养前BMMC通过其Gi偶联受体对凝血酶有反应的观察结果表明，与Gi3α蛋白表达水平不同的某个步骤的改变对于通过KL和3T3成纤维细胞衍生因子的协同作用获得对多阳离子化合物的反应性很重要。几条证据表明，3T3衍生因子似乎不同于已知的细胞因子、前列腺素和粘附分子，是一种不稳定的可溶性物质。
