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This Article Full Text Full Text (PDF) All Versions of this Article: 288/6/L1132    most recent 00429.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Buckley, C. A. Articles by Levine, S. J. Search for Related Content PubMed PubMed Citation Articles by Buckley, C. A. Articles by Levine, S. J.

Amino-terminal TACE prodomain attenuates TNFR2 cleavage independently of the cysteine switch

Pulmonary-Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland

Submitted 15 November 2004 ; accepted in final form 25 February 2005

TNF--converting enzyme (TACE, ADAM17) cleaves membrane-associated cytokines and receptors and thereby regulates inflammatory and immune events, as well as lung development and mucin production. For example, the TACE-mediated cleavage of the type II 75-kDa TNF receptor (TNFR2) generates a soluble TNF-binding protein that modulates TNF bioactivity. TACE is synthesized as a latent proenzyme that is retained in an inactive state via an interaction between its prodomain and catalytic domain. Although the formation of an intramolecular bond between a cysteine in the prodomain and a zinc atom in the catalytic site had been thought to mediate this inhibitory activity, it was recently reported that the cysteine-switch motif is not required. Here, we hypothesized that the amino terminus of the TACE prodomain might contribute to the ability of the prodomain to maintain TACE in an inactive state independently of a cysteine-switch mechanism. We synthesized a 37-amino acid peptide corresponding to TACE amino acids 18–54 (N-TACE^18–54) and assessed whether it possessed TACE inhibitory activity. In an in vitro model assay system, N-TACE^18–54 attenuated TACE-catalyzed cleavage of a TNFR2:Fc substrate. Furthermore, N-TACE^18–54 inhibited constitutive TNFR2 shedding from a human monocytic cell line by 42%. A 19-amino acid, leucine-rich domain, corresponding to TACE amino acids 30–48, demonstrated partial inhibitory activity. In summary, we have identified a subdomain within the amino terminus of the TACE prodomain that attenuates TACE catalytic activity independently of a cysteine-switch mechanism, which provides new insight into the regulation of TACE enzymatic activity.

tumor necrosis factor--converting enzyme; 1,10-phenanthroline; a disintegrin and metalloprotease; 55-kDa type I tumor necrosis factor receptor; 75-kDa type II tumor necrosis factor receptor