Olsen I, Dean M F, Muir H, Harris G
J Cell Sci. 1982 Jun;55:211-31. doi: 10.1242/jcs.55.1.211.
Fibroblasts deficient in beta-glucuronidase acquired high levels of this enzyme when they were co-cultured with concanavalin A-stimulated lymphocytes. Acquired enzyme activity, determined using a single-cell cytochemical assay, was directly proportional to the number of lymphocytes added and persisted for several days in fibroblasts maintained at high density. Lymphocytes did not secret significant levels of beta-glucuronidase into their culture medium, and did not release other substances able to induce synthesis of the enzyme by the deficient fibroblasts. Nor did beta-glucuronidase acquisition result from concanavalin A-mediated uptake of enzyme, since alpha-methylmannoside did not reduce acquired activity. Moreover, lymphocytes from various sources, whether unstimulated or activated by a different mitogen, bacterial lipopolysaccharide, were equally effective in promoting the appearance of beta-glucuronidase. Deficient fibroblasts did not acquire beta-glucuronidase by active endocytosis when co-cultured with lymphocytes, since enzyme extracted from lymphocytes was not itself effective in this respect. Furthermore, mannose 6-phosphate, which did inhibit, endocytosis by deficient fibroblasts of exogenous beta-glucuronidase prepared from 3T3 cells, had no effect on enzyme acquisition by fibroblasts during their co-culture with lymphocytes. Conversely, inhibitors of protein synthesis and energy metabolism, which did not interfere with endocytosis of exogenous enzyme, abolished the acquisition of beta-glucuronidase during co-culture. Deficient fibroblasts did not acquire beta-glucuronidase when they were cultured together with lymphocytes but separated from them by Millipore membranes permeable to exogenous enzyme. Thus, although the mechanism of acquisition is still unclear, the present results suggest that beta-glucuronidase is transferred from lymphocytes to deficient fibroblasts by a process in which direct cell-to-cell contact is obligatory.
缺乏β-葡萄糖醛酸酶的成纤维细胞在与伴刀豆球蛋白A刺激的淋巴细胞共培养时，获得了高水平的这种酶。使用单细胞细胞化学分析法测定的获得性酶活性与添加的淋巴细胞数量成正比，并在高密度培养的成纤维细胞中持续数天。淋巴细胞不会向其培养基中分泌大量的β-葡萄糖醛酸酶，也不会释放其他能够诱导缺陷成纤维细胞合成该酶的物质。β-葡萄糖醛酸酶的获得也不是由于伴刀豆球蛋白A介导的酶摄取，因为α-甲基甘露糖苷不会降低获得的活性。此外，来自各种来源的淋巴细胞，无论是否未受刺激或由不同的有丝分裂原（细菌脂多糖）激活，在促进β-葡萄糖醛酸酶的出现方面同样有效。当与淋巴细胞共培养时，缺陷成纤维细胞不会通过主动内吞作用获得β-葡萄糖醛酸酶，因为从淋巴细胞中提取的酶本身在这方面无效。此外，6-磷酸甘露糖虽然能抑制缺陷成纤维细胞对由3T3细胞制备的外源性β-葡萄糖醛酸酶的内吞作用，但对成纤维细胞与淋巴细胞共培养期间酶的获得没有影响。相反，不干扰外源性酶内吞作用的蛋白质合成和能量代谢抑制剂，消除了共培养期间β-葡萄糖醛酸酶的获得。当缺陷成纤维细胞与淋巴细胞一起培养但通过对外源性酶可渗透的微孔膜与它们分离时，它们不会获得β-葡萄糖醛酸酶。因此，尽管获得机制仍不清楚，但目前的结果表明，β-葡萄糖醛酸酶是通过一个必须有直接细胞间接触参与的过程从淋巴细胞转移到缺陷成纤维细胞的。
