TNF-α-converting enzyme cleaves the macrophage colony-stimulating factor receptor in macrophages undergoing activation
TNF-α-converting enzyme cleaves the macrophage colony-stimulating factor receptor in macrophages undergoing activation
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DOI：
10.4049/jimmunol.166.3.1583
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发表时间：
2001-02-01
影响因子：
4.4
通讯作者：
Dello Sbarba, P
中科院分区：
文献类型：
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作者：
Rovida, E;Paccagnini, A;Dello Sbarba, P
我们之前报道过，LPS、IL-2 和 IL-4 等巨噬细胞激活剂通过涉及蛋白激酶 C 和磷脂酶 C 的机制下调 M-CSFR。在这项研究中，我们表明 M-CSFR 从巨噬细胞表面脱落，并鉴定了负责 M-CSFR 裂解和下调的蛋白酶。阳离子螯合剂以及基于异羟肟酸酯的金属蛋白酶竞争性抑制剂可防止鼠 BAC.1-2F5 巨噬细胞中佛波酯（十四烷酰佛波醇肉豆蔻酸酯乙酸酯 (TPA)）或 LPS 引起的 M-CSFR 脱落。我们发现裂解 M-CSFR 的蛋白酶是一种跨膜酶，其表达受弗林蛋白酶样丝氨酸内切蛋白酶控制，该蛋白酶选择性地处理跨膜金属蛋白酶。在 TPA 刺激之前，用针对细胞外促 TNF 转换酶 (TACE) 催化结构域的抗体处理体内细胞，可抑制 M-CSFR 下调。 TACE 表达在 BAC.1-2F5 细胞中得到证实，并发现在阻断弗林蛋白酶依赖性加工后受到抑制。使用 TACE 阴性鼠 Dexter-ras-myc 细胞单核细胞，我们发现在这些细胞中 TPA 无法下调 M-CSFR 表达。这些数据表明 TACE 是 TPA 诱导的 M-CSFR 裂解所必需的。通过用抗 TNF Ab 处理体内细胞，排除了 TACE 通过释放 TNF 间接驱动裂解的可能性。因此，我们得出结论，TACE 是负责激活单核吞噬细胞中 M-CSFR 脱落和下调的蛋白酶。讨论了该机制可能的生理相关性。
We previously reported that macrophage activators such as LPS, IL-2, and IL-4 down-modulate the M-CSFR via a mechanism involving protein kinase C and phospholipase C, In this study, we showed that M-CSFR is shed from macrophage surface and identified the protease responsible for M-CSFR cleavage and down-modulation. The shedding of M-CSFR elicited by phorbol esters (tetradecanoylphorbol myristate acetate (TPA)) or LPS in murine BAC.1-2F5 macrophages was prevented by cation chelators, as well as hydroxamate-based competitive inhibitors of metalloproteases. We found that the protease cleaving M-CSFR is a transmembrane enzyme and that its expression is controlled by furin-like serine endoproteases, which selectively process transmembrane metalloproteases, M-CSFR down-modulation was inhibited by treating cells in vivo, before TPA stimulation, with an Ab raised against the extracellular, catalytic domain of proTNF-converting enzyme (TACE). TACE expression was confirmed in BAC.1-2F5 cells and found inhibited after blocking furin-dependent processing. Using TACE-negative murine Dexter-ras-myc cell monocytes, we found that in these cells TPA is unable to down-modulate M-CSFR expression. These data indicated that TACE is required for the TPA-induced M-CSFR cleavage. The possibility that the cleavage is indirectly driven by TACE via the release of TNF was excluded by treating cells in vivo with anti-TNF Ab. Thus, we concluded that TACE is the protease responsible for M-CSFR shedding and down-modulation in mononuclear phagocytes undergoing activation. The possible physiological relevance of this mechanism is discussed.