THE SOLUBLE INTERLEUKIN-6 RECEPTOR IS GENERATED BY SHEDDING
THE SOLUBLE INTERLEUKIN-6 RECEPTOR IS GENERATED BY SHEDDING
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DOI：
10.1002/eji.1830230226
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发表时间：
1993-02-01
影响因子：
5.4
通讯作者：
ROSEJOHN, S
中科院分区：
文献类型：
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作者：
MULLBERG, J;SCHOOLTINK, H;ROSEJOHN, S
人白细胞介素 6 受体 (IL-6R) 的配体结合亚基 (gp80) 在 COS-7 细胞中瞬时表达。代谢标记的蛋白质在 20 小时内从膜上定量释放。我们鉴定出转染的 COS-7 细胞在纯化至同质性和 N 末端测序后释放的蛋白质为 gp80/IL-6R 的可溶形式。 4beta-phorbol-12-myristate-13-acetate 强烈诱导 gp80 蛋白的脱落，表明该过程受到蛋白激酶 C (PKC) 的调节。共转染 PKC 表达质粒导致 gp80 蛋白脱落增强的发现进一步证实了这一点。由于用所有已知类别的蛋白酶的抑制剂处理细胞无法阻止 gp80 的脱落，因此似乎涉及一种新的蛋白酶。作为对照，将不相关的膜蛋白（水泡性口炎病毒糖蛋白）转染到 COS-7 细胞中并分析脱落情况。由于该蛋白的周转不是通过脱落介导的，因此我们得出结论，COS-7细胞中gp80的释放是一个特定的过程。脱落的gp80蛋白特异性结合IL-6，并且该复合物对人肝癌细胞显示出生物活性。 PMA 处理后，人外周血单核细胞将可溶形式的 gp80 蛋白释放到培养基中，表明 PKC 调节的脱落是可溶性 IL-6R 生成的生理机制。
The ligand-binding subunit (gp80) of the human interleukin-6 receptor (IL-6R) was transiently expressed in COS-7 cells. The metabolically labeled protein was shown to be quantitatively released from the membrane within 20 h. We identified the protein released from the transfected COS-7 cells after purification to homogeneity and N-terminal sequencing as a soluble form of the gp80/IL-6R. Shedding of the gp80 protein was strongly induced by 4beta-phorbol-12-myristate-13-acetate, indicating that the process was regulated by protein kinase C (PKC). This was further corroborated by the finding that co-transfection of a PKC expression plasmid led to enhanced shedding of the gp80 protein. Since shedding of gp80 could not be prevented by treatment of the cells with inhibitors of all known classes of proteases, a novel protease seems to be involved. As a control, an unrelated membrane protein (vesicular stomatitis virus glycoprotein) was transfected into COS-7 cells and analyzed for shedding. Since the turnover of this protein was not mediated by shedding, we conclude that the release of gp80 from COS-7 cells is a specific process.The shed gp80 protein specifically binds IL-6, and this complex shows biological activity on human hepatoma cells. Human peripheral blood monocytes released a soluble form of the gp80 protein into the culture medium upon PMA treatment indicating that PKC-regulated shedding is the physiological mechanism of generation of the soluble IL-6R.