TNF-alpha-converting enzyme cleaves the macrophage colony-stimulating factor receptor in macrophages undergoing activation

• Published in: The Journal of immunology (1950) Vol. 166; no. 3; pp. 1583 - 1589
• Main Authors: Rovida, E, Paccagnini, A, Del Rosso, M, Peschon, J, Dello Sbarba, P
• Format: Journal Article
• Language: English
• Published: United States 01-02-2001
• Subjects: ADAM Proteins; ADAM17 Protein; Animals; Antibodies, Monoclonal - pharmacology; Catalytic Domain - immunology; Cell Line; Cell Line, Transformed; Down-Regulation - drug effects; Down-Regulation - immunology; Enzyme Activation - drug effects; Enzyme Activation - immunology; Humans; Hydrolysis; Lipopolysaccharides - pharmacology; Macrophage Activation - drug effects; Macrophage Activation - immunology; Macrophage colony-stimulating factor receptors; Macrophages - drug effects; Macrophages - enzymology; Macrophages - immunology; Macrophages - metabolism; Metalloendopeptidases - immunology; Metalloendopeptidases - isolation & purification; Metalloendopeptidases - metabolism; Mice; Mice, Inbred A; Mice, Inbred BALB C; Mice, Inbred C57BL; Monocytes - drug effects; Monocytes - enzymology; Monocytes - immunology; Receptor, Macrophage Colony-Stimulating Factor - antagonists & inhibitors; Receptor, Macrophage Colony-Stimulating Factor - metabolism; TACE protein; Tetradecanoylphorbol Acetate - pharmacology; Tumor Necrosis Factor-alpha - metabolism
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.166.3.1583

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.