TNF-alpha-converting enzyme cleaves the macrophage colony-stimulating factor receptor in macrophages undergoing activation.
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.
Rovida
E
E
Dipartimento di Patologia e Oncologia Sperimentali, Università di Firenze, Florence, Italy. Immunex, Seattle, WA 98101, USA.
Paccagnini
A
A
Del Rosso
M
M
Peschon
J
J
Dello Sbarba
P
P
D051722:ADAM Proteins; D000072198:ADAM17 Protein; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D020134:Catalytic Domain / Q000276:immunology; D002460:Cell Line; D002461:Cell Line, Transformed; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D006868:Hydrolysis; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000187:drug effects / Q000276:immunology*; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D008666:Metalloendopeptidases / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D016186:Receptor, Macrophage Colony-Stimulating Factor; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; C000606463:Adam17 protein, mouse; D013755:Tetradecanoylphorbol Acetate