Stimulation-induced down-regulation of tumor necrosis factor-α converting enzyme
Stimulation-induced down-regulation of tumor necrosis factor-α converting enzyme
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DOI：
10.1074/jbc.275.19.14598
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发表时间：
2000-05-12
影响因子：
4.8
通讯作者：
Black, RA
中科院分区：
文献类型：
--
作者：
Doedens, JR;Black, RA
许多蛋白质的胞外结构域，包括生长因子、细胞因子、受体和粘附分子，都是通过蛋白水解从细胞中释放出来的，这一过程被称为“脱落”。肿瘤坏死因子- α转换酶（Tumor necrosis factor- α converting enzyme, TACE/ADAM-17）是一种金属蛋白酶分解素，能够释放肿瘤坏死因子- α等蛋白。为了研究TACE介导的脱落调控，我们检测了刺激细胞对TACE定位和表达的影响。免疫荧光显微镜显示未处理细胞表面有点状分布的TACE，脂多糖刺激单核细胞不影响TACE染色。肉豆蔻酸酯（Phorbol 12-myristate 13-acetate， PMA）是一种有效的脱毛诱导剂，可降低TACE的细胞表面染色。表面生物素化实验证实并扩展了这一观察；PMA降低了表面生物素化TACE的半衰期，但不增加细胞表面总蛋白的周转率。在TACE下调的细胞培养基中未检测到可溶的TACE片段，并且当内吞作用被抑制时，TACE不下调。抗体摄取实验表明，细胞表面的TACE内化是对PMA的反应。令人惊讶的是，一种金属蛋白酶抑制剂阻止了pma诱导的TACE转换。因此，PIMA激活脱落并导致主要“脱落酶”的下调，这表明诱导脱落可能是通过减少细胞表面活性TACE数量的机制来调节的。
The extracellular domains of many proteins, including growth factors, cytokines, receptors, and adhesion molecules, are proteolytically released from cells, a process termed "shedding." Tumor necrosis factor-alpha converting enzyme (TACE/ADAM-17) is a metalloprotease-disintegrin that sheds tumor necrosis factor-alpha and other proteins. To study the regulation of TACE-mediated shedding, we examined the effects of stimulation of cells on TACE localization and expression. Immunofluorescence microscopy revealed a punctate distribution of TACE on the surface of untreated cells, and stimulation of monocytic cells with lipopolysaccharide did not affect TACE staining. Phorbol 12-myristate 13-acetate (PMA), a potent inducer of shedding, decreased cell-surface staining for TACE. Surface biotinylation experiments confirmed and extended this observation; PMA decreased the half-life of surface-biotinylated TACE without increasing the turnover of total cell-surface proteins. Soluble fragments of TACE were not detected in the medium of cells that had down-regulated TACE, and TACE was not down-regulated when endocytosis was inhibited. Antibody uptake experiments suggested that cell-surface TACE was internalized in response to PMA. Surprisingly, a metalloprotease inhibitor prevented the PMA-induced turnover of TACE. Thus, PIMA activates shedding and causes the down-regulation of a major "sheddase," suggesting that induced shedding may be regulated by a mechanism that decreases the amount of active TACE on the cell surface.