Substrate specificity and inducibility of TACE (tumour necrosis factor α-converting enzyme) revisited: the Ala-Val preference, and induced intrinsic activity

2003 ◽  
Vol 70 ◽  
pp. 39-52 ◽  
Author(s):  
Roy A. Black ◽  
John R. Doedens ◽  
Rajeev Mahimkar ◽  
Richard Johnson ◽  
Lin Guo ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Recent Work ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Transforming Growth Factor ◽  
Intrinsic Activity ◽  
Converting Enzyme ◽  
Tumour Necrosis Factor Α ◽  
Factor Α ◽  
Necrosis Factor

Tumour necrosis factor α (TNFα)-converting enzyme (TACE/ADAM-17, where ADAM stands for a disintegrin and metalloproteinase) releases from the cell surface the extracellular domains of TNF and several other proteins. Previous studies have found that, while purified TACE preferentially cleaves peptides representing the processing sites in TNF and transforming growth factor α, the cellular enzyme nonetheless also sheds proteins with divergent cleavage sites very efficiently. More recent work, identifying the cleavage site in the p75 TNF receptor, quantifying the susceptibility of additional peptides to cleavage by TACE and identifying additional protein substrates, underlines the complexity of TACE-substrate interactions. In addition to substrate specificity, the mechanism underlying the increased rate of shedding caused by agents that activate cells remains poorly understood. Recent work in this area, utilizing a peptide substrate as a probe for cellular TACE activity, indicates that the intrinsic activity of the enzyme is somehow increased.

scholarly journals N-terminal cleavage of proTGFα occurs at the cell surface by a TACE-independent activity

2005 ◽  
Vol 389 (1) ◽  
pp. 161-172 ◽  
Author(s):  
Pedro P. JUANES ◽  
Laura FERREIRA ◽  
Juan Carlos MONTERO ◽  
Joaquín ARRIBAS ◽  
Atanasio PANDIELLA
Keyword(s):  
Cell Surface ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Transforming Growth Factor ◽  
Signal Sequence ◽  
Tumour Necrosis Factor Α ◽  
Transforming Growth Factor Α ◽  
Factor Α ◽  
Necrosis Factor

ProTGFα (transforming growth factor α precursor) maturation and conversion into soluble TGFα is a complex process that involves three proteolytic steps. One, that occurs co-translationally, eliminates the signal sequence. Another, occurring at the juxtamembrane domain, solubilizes TGFα. A third cleavage removes the N-terminal extension of proTGFα. This latter step has been poorly studied, mainly because of the rapid kinetics of this cleavage. In the present study, we have designed a strategy to analyse several aspects regarding this N-terminal cleavage. In vivo treatment with the hydroxamate-based metalloprotease inhibitors BB3103 or TAPI-2 (tumour necrosis factor-α protease inhibitor 2) reversibly induced accumulation of forms of proTGFα that included the N-terminal extension. N-terminal shedding was rapid, and occurred at the cell surface. However, the machinery responsible for the N-terminal cleavage was inactive in other cellular sites, such as the endoplasmic reticulum. Experiments of proTGFα expression and maturation in cells deficient in TACE (tumour-necrosis-factor-α-converting enzyme) activity indicated that this protease was dispensable for N-terminal processing of proTGFα in vivo, but was required for regulated cleavage at the C-terminus. These findings indicate that TACE is not involved in N-terminal processing of proTGFα, and suggest differences in the machineries that control the cleavage at both ends of TGFα within its precursor.

Constitutive shedding of the amyloid precursor protein ectodomain is up-regulated by tumour necrosis factor-α converting enzyme

2001 ◽  
Vol 357 (3) ◽  
pp. 787-794 ◽  
Author(s):  
Barbara E. SLACK ◽  
Leona K. MA ◽  
Ching Ching SEAH
Keyword(s):  
Amyloid Precursor Protein ◽  
Muscarinic Receptor ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Transmembrane Protein ◽  
Precursor Protein ◽  
Converting Enzyme ◽  
Tumour Necrosis Factor Α ◽  
Factor Α ◽  
Necrosis Factor

The amyloid precursor protein (APP) of Alzheimer's disease is a transmembrane protein that is cleaved within its extracellular domain, liberating a soluble N-terminal fragment (sAPPα). Putative mediators of this process include three members of the ADAM (a disintegrin and metalloprotease) family, ADAM9, ADAM10 and ADAM17/TACE (tumour necrosis factor-α converting enzyme). Tumour necrosis factor-α protease inhibitor (TAPI-1), an inhibitor of ADAMs, reduced constitutive and muscarinic receptor-stimulated sAPPα release in HEK-293 cells stably expressing M3 muscarinic receptors. However, the former was less sensitive to TAPI-1 (IC50 = 8.09μM) than the latter (IC50 = 3.61μM), suggesting that these processes may be mediated by different metalloproteases. Constitutive sAPPα release was increased several-fold in cells transiently transfected with TACE, and this increase was proportional to TACE expression. In contrast, muscarinic-receptor-activated sAPPα release was not altered in TACE transfectants. TACE-dependent constitutive release of co-transfected APP695 was inhibited by TAPI-1 with an IC50 of 0.92μM, a value significantly lower than the IC50s for inhibition of either constitutive or receptor-regulated sAPPα shedding mediated by endogenous secretases. The results indicate that TACE is capable of catalysing constitutive α-secretory cleavage of APP, but it is likely that additional members of the ADAM family mediate endogenous constitutive and receptor-coupled release of sAPPα in HEK-293cells.

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